3 posts categorized "Nitric Oxide"

April 04, 2013

What's Wrong With Nitric Oxide - Part 3


Ask a cardiologist about the effects of nitric oxide, and there’s a good chance you’ll hear about the chemical’s role in dilating blood vessels, lowering blood pressure, and supporting cardiovascular health.

Ask a neurologist about nitric oxide, and you’ll likely to hear about the widespread cellular damage this chemical can cause, and how an excess of nitric oxide in the brain is now thought to be a major contributing factor to degenerative neurological diseases like Alzheimer’s disease, Parkinson’s disease, and ALS.

And, ask an oncologist for yet a third opinion, and you may hear about nitric oxide’s role in either suppressing tumor growth – as a potent tumor–killing agent of the immune system; or, conversely, its role in stimulating tumor growth by triggering angiogenesis, the formation of the new blood vessels tumors need to survive.

So, clearly, nitric oxide has many varied effects within our bodies – some beneficial, and some very harmful. This is the fundamental reason why so many attempts to manipulate nitric oxide levels, either pharmacologically or nutritionally, have met with failure.

As relates to the cardiovascular system, for example, it was initially thought that increasing nitric oxide levels would be the key to correcting what was simplistically assumed to be a “deficiency” of nitric oxide in cardiovascular disease. But this approach is quickly being abandoned, as a myriad of unforeseen (and sometimes fatal) side effects have accompanied nitric oxide–boosting therapies.

Of course, some nutritional supplement companies, and some health practitioners (whose products and recommendations lag decades behind the actual research) continue to recommend that we indiscriminately increase our nitric oxide levels with various nitric oxide–boosting concoctions. But the flaws inherent in such an approach are now well–documented, even if not yet well–publicized.

In light of what we now know about the often harmful effects of nitric oxide, it seems that we’ll want to do everything we can, not merely to increase nitric oxide levels, but to keep nitric oxide production under tight control throughout the body.

A Brief Review

When produced, nitric oxide rapidly reacts with a chemical called superoxide, to form a particularly damaging chemical called peroxynitrite. It’s now believed that this process is largely to blame for many of the harmful effects of nitric oxide.

When nitric oxide–boosting therapies are employed – like the use of the amino acid precursor to nitric oxide, arginine – or the nitric oxide pro–drug, nitroglycerin, the production of peroxynitrite increases right along with nitric oxide itself. And the result has often been a short–term benefit, marred by longer–term harm.

Recent research has found, however, that we may be able to give our nitric oxide metabolism a nutritional “tune–up,” without increasing our burden of harmful nitric oxide byproducts. The answer lies not in “boosting” nitric oxide, but in supplying our body with the nutrients needed to metabolize nitric oxide safely and efficiently.

In the last Integrated Supplements Newletter, we looked at nutritional factors like folic acid, Vitamin B6, and Vitamin B12 which may reduce homocysteine and simultaneously protect the fragile nitric oxide cofactor, called tetrahydrobiopterin.

We saw how antioxidant nutrients like Vitamin E, Vitamin C, selenium, and whey protein isolate may help to reduce the oxidative stress which constantly threatens nitric oxide metabolism.

We even saw how cocoa flavonols and creatine monohydrate may exert especially beneficial effects on nitric oxide metabolism.

Building on these strategies, we’ll now look at other nutritional factors which will help support proper nitric oxide metabolism in the cardiovascular system and beyond.

This Is Your Brain on Nitric Oxide

In the late 1980’s, an iconic public service announcement on television depicted a frying egg, while an actor sternly warned an entire generation of impressionable Americans, “This is your brain on drugs.” And while this PSA offered a powerful visual metaphor of the effects certain drugs can have on brain function, it may serve us well to look a little deeper into the molecular biology of the matter.

It turns out that much of the toxicity associated with neuro–active drugs is ultimately due to the actions of nitric oxide. In fact, the chemical inhibition of the enzymes which produce nitric oxide has been shown to abolish the toxicity associated with both methamphetamine and cocaine.

Study Link – Nitric oxide (NO) synthase inhibitors abolish cocaine–induced toxicity in mice.

Quote from the above study:

Repeated administration of cocaine (45 mg/kg/day) for 7 days to Swiss–Webster mice resulted in a progressive increase in the convulsive response to cocaine and augmentation in lethality rate. Pretreatment with the nitric oxide (NO) synthase inhibitors, L–NAME (100 mg/kg/day) or NO–Arg (25 mg/kg/day), prior to cocaine administration completely abolished the sensitization to the convulsive and lethal responses to cocaine. These findings suggest a role for NO in cocaine–induced toxicity.

Study Link – Role of nitric oxide in methamphetamine neurotoxicity : Protection by 7–nitroindazole, an inhibitor of neuronal nitric oxide synthase.

Quote from the above study:

These findings indicate a role for nitric oxide in methamphetamine–induced neurotoxicity and also suggest that blockade of NOS may be beneficial for the management of Parkinson's disease.

And you don’t have to be a drug–user to be susceptible to the neurotoxic effects of nitric oxide. The damage caused by nitric oxide and its metabolites has been very strongly linked with age–related brain degeneration, and disorders such as Parkinson’s disease, ALS, and Alzheimer’s disease.

Study Link – Nitric oxide neurotoxicity.

Quote from the above study:

NO has many roles in the central nervous system as a messenger molecule, however, when generated in excess NO can be neurotoxic. Excess NO is in part responsible for glutamate neurotoxicity in primary neuronal cell culture and in animal models of stroke. It is likely that most of the neurotoxic actions of NO are mediated by peroxynitrite (ONOO−), the reaction product from NO and superoxide anion.

Study Link – Widespread Peroxynitrite–Mediated Damage in Alzheimer's Disease.

Quote from the above study:

These findings provide strong evidence that peroxynitrite is involved in oxidative damage of Alzheimer's disease.

Studies have found, as well, that mice bred to be deficient in one of the nitric oxide–producing enzymes had decreased mortality, and were significantly protected from many of the manifestations of Alzheimer’s disease:

Study Link – Protection from Alzheimer's–like disease in the mouse by genetic ablation of inducible nitric oxide synthase.

Quote from the above study:

Deficiency of iNOS substantially protected the AD–like mice from premature mortality, cerebral plaque formation, increased ß–amyloid levels, protein tyrosine nitration, astrocytosis, and microgliosis. Thus, iNOS seems to be a major instigator of ß–amyloid deposition and disease progression. Inhibition of iNOS may be a therapeutic option in AD.

And, in addition to degenerative brain diseases, nitric oxide has also been implicated in other neurological disorders such as migraine headaches:

Study Link – Nitric oxide is a key molecule in migraine and other vascular headaches.

Study Link – Nitric oxide–induced headache in patients with chronic tension–type headache.

Study Link – Nitric oxide supersensitivity: a possible molecular mechanism of migraine pain.

The following study even found that those with migraine headaches may be at increased risk of developing Alzheimer’s disease later in life. The common role of nitric oxide in each disorder helps to explain why.

Study Link – Risk factors for Alzheimer's disease: a population–based, longitudinal study in Manitoba, Canada.

Quote from the above study:

The association of AD with a history of migraines and occupational exposure to defoliants/fumigants is of particular interest because these are biologically plausible risk factors.

Nitric oxide is even suspected to play a major role in the development of the chronic ringing in the ears known as tinnitus:

Study Link – The NO/ONOO– cycle as the etiological mechanism of tinnitus.

Study Link – Pharmacological models for inner ear therapy with emphasis on nitric oxide.

At first glance, it may seem ironic that nitric oxide, a compound deemed so beneficial for cardiovascular health, could be so universally maligned for its harmful role in neurological health.

But of course, we now know that there is much more to nitric oxide metabolism than was once assumed. Though a certain amount of nitric oxide is necessary for cardiovascular function, any excess can be decidedly harmful. As we’ll see, the same general principles (ensuring the proper metabolism of nitric oxide) apply when addressing nitric oxide metabolism in the brain and in the neurological system.

Nitric Oxide – Inflammatory Chemical

One of the ways in which nitric oxide can be produced in the body is via an enzyme known as inducible nitric oxide synthase (iNOS). Immune cells, called macrophages, contain iNOS, and can produce nitric oxide to destroy invading viruses or bacteria, or under other conditions of stress and trauma. This means that nitric oxide is an integral part of our bodies’ immune system and inflammatory response, but it also means that the production of nitric oxide by macrophages can very easily spiral out of control.

Unlike endothelial nitric oxide synthase (eNOS, the form of nitric oxide synthase which produces NO in the blood vessels), iNOS can churn out massive amounts of nitric oxide virtually non–stop. This excess nitric oxide (and the metabolites produced from it) can be particularly harmful to the delicate, lipid–rich structures of the brain. And, as we now know, inflammation and tissue damages often proceeds in a vicious downward spiral, perpetuating even more tissue damage and inflammation. This is a major reason why nitric oxide production needs to be kept under control in conditions of stress, aging, and disease.

As we mentioned in previous issues of the Integrated Supplements Newsletter, we ideally want any inflammatory response of our immune system to be “short and sweet” – sufficient enough to deal with the stress at hand, but not excessive enough to cause a self–perpetuating spiral of tissue destruction.

Reducing Inflammation Safely

It’s now widely accepted that all degenerative diseases share the common thread of excessive and uncontrolled inflammation – including the over–production of nitric oxide. But, for as many anti–inflammatory foods, drugs, and supplements as we have at our disposal, reducing systemic inflammation safely still takes a bit of biochemical know–how.

For instance, it’s well–documented that some “anti–inflammatory” strategies may ultimately be destined to do more harm than good. The dangerous side effects associated with the wildly popular COX–2 inhibitor medication, Vioxx® are a chilling reminder of this; and, in the May 2008 edition of the Integrated Supplements Newsletter, we saw how even many of the “anti–inflammatory” fats often recommended by the health–food and nutritional supplement crowd (omega–3s, for example) may predispose us to tissue fragility and destruction when consumed in excess.

On the other hand, when we attempt to reduce inflammation in a physiologically sound manner, we’ll find that the pieces of the puzzle fit together in such a way as to actually give us far–reaching health benefits.

As relates to nitric oxide, we’ll find that some nutritional substances can serve to reduce the excess production of inflammatory nitric oxide produced by the immune system, while at the same time improving the bioavailability of the nitric oxide produced within the cardiovascular system. The most important nutrient offering such a two–pronged benefit is likely to be the often overlooked mineral, magnesium.

Magnesium and Nitric Oxide

According to data from the United States Department of Agriculture, a full 68% of Americans fail to consume the minimum recommended amount of magnesium each day; and a stunning body of scientific evidence indicates that very few nutritional deficiencies are as widespread, or as deadly, as magnesium deficiency.

Many people know that the electrolyte mineral, magnesium, is involved in “electrical” functions of the body like the heartbeat, and nerve impulses, but very few people realize that the presence of a magnesium deficiency leads to an absolutely massive increase in various markers of systemic inflammation.

The list of biological substances increased in the body when magnesium is deficient reads like a “who’s–who” of inflammatory chemicals. C–reactive protein, substance P, cytokines, prostaglandins, histamine, and of course, nitric oxide all become elevated when magnesium levels are sub–optimal.

Study Link – The nerve–heart connection in the pro–oxidant response to Mg–deficiency.

Quote from the above study:

In rodent models of dietary MgD [magnesim deficiency], a significant rise in circulating levels of proinflammatory neuropeptides such as substance P (SP) and calcitonin gene–related peptide among others, was observed within days (1–7) of initiating the Mg–restricted diet, and implicated a neurogenic trigger for the subsequent inflammatory events; this early "neurogenic inflammation" phase may be mediated in part, by the Mg–gated N–methyl–D–aspartate (NMDA) receptor/channel complex. Deregulation of the NMDA receptor may trigger the abrupt release of neuronal SP from the sensory–motor C–fibers to promote the subsequent pro–inflammatory changes: elevations in circulating inflammatory cells, inflammatory cytokines, histamine, and PGE(2) levels, as well as formation of nitric oxide, reactive oxygen species, lipid peroxidation products, and depletion of key endogenous antioxidants. Concurrent elevations of tissue CD14, a high affinity receptor for lipopolyssacharide, suggest that intestinal permeability may be compromised leading to endotoxemia. If exposure to these early (1–3 weeks MgD) inflammatory/pro–oxidant events becomes prolonged, this might lead to impaired cardiac function, and when co–existing with other pathologies, may enhance the risk of developing chronic heart failure.

And, as relates specifically to nitric oxide, it’s interesting to note that magnesium deficiency has the effect of increasing the “inflammatory” nitric oxide (produced by iNOS), rather than the cardioprotective type produced by eNOS (called constitutive NOS in the following study):

Study Link – Magnesium deficiency in rats induces a rise in plasma nitric oxide.

Quote from the above study:

Magnesium deficiency in rats leads to an oxidative stress involving an increased production of radical oxygen species. The present study was designed to examine the effect of experimental magnesium deficiency on plasma nitric oxide (NO) level and nitric oxide synthases (NOS) activities in rats. The data show that the concentration of NO is markedly increased in plasma of magnesium–deficient rats. This rise in plasma NO results from activation of inducible nitric oxide synthase (iNOS) rather than of the constitutive form (cNOS) of the enzyme. These data are in agreement with previous observations indicating that inflammation occurs during magnesium–deficiency and provide an additional cause of oxidative lesions through formation of peroxynitrite from nitric oxide and superoxide anion.

Study Link – Magnesium–deficient medium enhances NO production in alveolar macrophages isolated from rats.

Quote from the above study:

These results suggest that Mg(2+) deficiency enhances NO production via iNOS by alveolar macrophages.

And knowing that nitric oxide is largely responsible for much of the brain deterioration of Alzheimer’s, it’s interesting to find that there may be a direct correlation between magnesium status and the progression of the disease. The following study found that as magnesium status worsened so too did the progression of Alzheimer’s disease as evidenced by falling scores on cognitive tests:

Study Link – Serum magnesium level and clinical deterioration in Alzheimer's disease.

Quote from the above study:

Our data suggest that there is a relationship between serum Mg levels and the degree of Alzheimer's disease and that the determination of the Mg level at various stages may provide valuable information in further understanding the progression and treatment of Alzheimer's disease.

Because of the multiple roles magnesium plays in reducing systemic inflammation and excessive nitric oxide production, a lack of magnesium can exert effects at every level of biological functioning. As evidence, the widespread magnesium deficiency caused by our modern diet is known to be a major factor in the increasing prevalence of all degenerative diseases of aging, including not only brain diseases, but heart disease, diabetes and cancer as well.

And considering the fact that so few individual foods contain high amounts of magnesium (and the fact that multivitamins never contain sufficient amounts) it’s safe to say that a stand–alone magnesium product is often the single most important nutritional supplement a health–conscious person can take. But, even magnesium alone may not be enough to fully rectify a magnesium deficiency. Other nutritional factors, such as selenium, potassium, vitamin B6, and vitamin D, are also needed for proper magnesium absorption and metabolism.

Study Link – The multifaceted and widespread pathology of magnesium deficiency.

Quote from the above study:

Unfortunately, Mg absorption and elimination depend on a very large number of variables, at least one of which often goes awry, leading to a Mg deficiency that can present with many signs and symptoms. Mg absorption requires plenty of Mg in the diet, [selenium], parathyroid hormone (PTH) and vitamins B6 and D.

Curcumin and Nitric Oxide

In addition to correcting outright nutritional deficiencies, there are many other steps we can take to reduce the inflammatory over–production of nitric oxide.

It seems that nature, in her infinite wisdom, has supplied us with many plant–based anti–inflammatory substances which may impart particularly powerful effects when it comes to scavenging nitric oxide. One of the most notable of such substances is the yellow/orange pigment from turmeric, called curcumin.

Turmeric, a member of the ginger family, is a spice which has been long–used in Indian and Chinese cuisine, and respective systems of medicine. Recent research has uncovered that many of the health–promoting benefits traditionally associated with turmeric may be attributable specifically to curcumin; and interestingly, we find that curcumin may act as a powerful scavenger of nitric oxide.

Study Link – Nitric oxide scavenging by curcuminoids.

Quote from the above study:

The results indicate curcumin to be a scavenger of nitric oxide. Because this compound is implicated in inflammation and cancer, the therapeutic properties of curcumin against these conditions might be at least partly explained by its free–radical scavenging properties, including those toward nitric oxide.

And, although some research indicates that curcumin may be poorly absorbed, there’s reason to believe that curcumin and turmeric may exert their health–benefits despite this fact. Even though turmeric contains only about 3% curcumin at the most, and curcumin is likely to be poorly absorbed, preliminary studies conducted in India (where turmeric is very widely used in cooking) have shown some of the lowest levels of Alzheimer’s disease ever recorded – results which held true for both rural and urban communities:

Study Link – Incidence of Alzheimer's disease in a rural community in India: the Indo–US study.

Quote from the above study:

These are the first AD incidence rates to be reported from the Indian subcontinent, and they appear to be among the lowest ever reported. However, the relatively short duration of follow–up, cultural factors, and other potential confounders suggest caution in interpreting this finding.

Study Link – Prevalence of dementia in an urban Indian population.

Quote from the above study:

In the population surveyed, the prevalence of AD and other dementias is less than that reported from developed countries but similar to results of other studies in India.

If these results have anything to do with turmeric consumption, the chances are good that most of us can benefit from simply adding more turmeric–rich meals to our diet. Curcumin extracts do exist as nutritional supplements, but they are very costly relative to the very inexpensive spice, turmeric.

And research indicates that we can find many other inexpensive ways to reduce the inflammatory effects of nitric oxide as close as the local grocery store. Antioxidant compounds in (green and black) tea, coffee, red wine, cocoa, and pomegranate have all been shown to protect against the inflammatory over–production of nitric oxide.

Study Link – Protection against nitric oxide toxicity by tea.

Study Link – The coffee diterpene kahweol suppress the inducible nitric oxide synthase expression in macrophages.

Study Link – Synergy between ethanol and grape polyphenols, quercetin, and resveratrol, in the inhibition of the inducible nitric oxide synthase pathway

Study Link – Effects of an aqueous extract of cocoa on nitric oxide production of macrophages activated by lipopolysaccharide and interferon–gamma.

Study Link – Pomegranate juice protects nitric oxide against oxidative destruction and enhances the biological actions of nitric oxide.

As we’ve seen in this series of articles, nitric oxide metabolism can be more than a bit complicated. And despite a frenzy of conflicting nitric oxide research, we’ve seen the unfortunate tendency of both the medical community and the nutritional supplement industry to “jump the gun”, and rush to market products based upon dangerous misinterpretations of the scientific evidence.

But, yet again, only as we look deeper into the research, does the big picture become clear. Only then can we address fundamental biological imbalances, and not merely symptoms or biological markers.

And again, we see that carefully–chosen, time–tested natural foods and nutrients offer us the greatest long–term benefit – with little to no risk. The nutrients and foods mentioned in this series of articles are the substances the human body has always needed to support health, but they are often the substances most conspicuously lacking from our modern food supply.

In the final analysis, nitric oxide is just another example of a biological chemical whose actions can seem baffling and paradoxical when we forget to look first to nature for the answers. Only when we remember our role as a part of nature, will the pieces of the puzzle fall neatly into place.

About Us: At Integrated Supplements, our goal is to bring you the wellness information and products you need to live your life to the fullest. We are dedicated to producing the highest–quality, all–natural nutritional supplements; and to educating the world on the health promoting power of proper nutrition. You can find out more by visiting: www.IntegratedSupplements.com


These statements have not been evaluated by the FDA. No Integrated Supplements product is intended to diagnose, treat, cure or prevent any disease.


What's Wrong With Nitric Oxide - Part 2


Given the sometimes overwhelming complexity of biological systems, there’s an almost unavoidable tendency, even among top researchers, and medical professionals, to simplify matters by labeling certain biochemicals simplistically as either “good” or “bad.”

But rarely in biology do substances wear only black or white hats. More realistically, we find that certain substances produced within the body exert protective roles in some situations, but in other situations, when regulatory and stabilizing systems fail, these same substances may be harmful if produced in excess, or metabolized inefficiently. In other words, in an ironic twist of fate, many biological molecules have the tendency to exacerbate the very bodily damage they were initially produced to protect against.

As an example, many researchers believe that the cholesterol which leads to the production of atherosclerotic plaque in the arteries is initially a protective substance. The thinking is, that as a vital component of cellular structure, cholesterol is drawn to the artery to “patch up” microscopic injuries in the arterial wall. It’s only when various cell–signaling and inflammatory systems go awry, however, that cholesterol is altered from a protective to a pathological molecule, eventually resulting in the build–up of the cholesterol–laden plaque associated with heart disease.

Another example of such a two–faced biological chemical is the gaseous signaling molecule, nitric oxide.

Produced as a protective molecule under periods of stress and trauma, nitric oxide is most well–known as a substance integral for the proper dilation of blood vessels. The blood vessels of people with cardiovascular disease, high blood pressure, insulin resistance, and diabetes are almost always dangerously resistant to the vasodilating effects of nitric oxide; and as such, strategies to increase nitric oxide levels and to restore proper nitric oxide signaling in these patients represent a major focus of current nutritional and pharmaceutical intervention.

But so far, the results of such strategies have failed to deliver much in the way of meaningful benefit – and some have even proven deadly. Such puzzling outcomes speak to the dual nature of nitric oxide, as well as the intricate complexity of its metabolism.

As the big picture of nitric oxide becomes clearer, we now know that while a deficiency of nitric oxide function is strongly implicated in cardiovascular disorders, an excess of nitric oxide, and inefficient nitric oxide metabolism, are known to exacerbate the vascular damage associated with heart disease. Nitric oxide and its metabolites also play particularly crucial roles in the spread of cancer, and the development of degenerative brain disorders like Alzheimer’s and Parkinson’s disease.

In recent years, many companies within the nutritional supplement industry have offered up “nitric oxide–boosting” formulas containing amino acid precursors of nitric oxide such as arginine and citrulline. The marketing behind such products obviously focuses on the supposedly “good” roles of nitric oxide, but the research that exists indicates that such products may possess the potential to do serious harm in certain populations, or if taken over extended periods of time.

So, rather than simply finding ways of “boosting” or suppressing nitric oxide levels to treat or prevent different disorders, our goal will be to find nutritional and lifestyle strategies to modulate nitric oxide production, ensuring proper, healthy, nitric oxide signaling and metabolism in all tissues of the body for a lifetime.

To do this requires that we first take a look at the biological “assembly line” responsible for the production of nitric oxide. Though complicated at first, we’ll find that the answers we seek can be found only by a glimpse into the inner workings of our molecular biochemistry.

The Nitric Oxide Synthases

It’s well–known that our body produces nitric oxide (NO) from the amino acid arginine, and that the production of nitric oxide from arginine is catalyzed by a group of enzymes known as nitric oxide synthases (NOS). At least three (major) types of NOS exist, each classified by the types of tissues and cells in which they are found (the fact that nitric oxide can be produced by several different enzymes, and can be used for many different biological reactions, may be our first clue as to why NO may be beneficial in some instances, and harmful in others).

Endothelial nitric oxide synthase, or eNOS, can be found in the lining of the blood vessels, called the endothelium. The nitric oxide produced by eNOS triggers vasodilation, and is an important factor in regulating blood pressure. Endothelial nitric oxide further supports cardiovascular health by inhibiting the “stickiness” of blood cells called platelets, and preventing platelets from adhering to the endothelium – an early phenomenon in the development of atherosclerosis. It has been noted that all known or suspected risk factors for cardiovascular disease – including high cholesterol, high blood pressure, high homocysteine, high triglycerides, and smoking – involve the reduced bioavailability of nitric oxide within the endothelium.

Neuronal nitric oxide, or nNOS, is found in neurons in the brain and nervous system. The nitric oxide produced by nNOS acts as a neurotransmitter and signaling molecule, and, in precise amounts, may play a role in memory and learning. Disorders of nitric oxide production by nNOS, on the other hand, may play a role in many neurological diseases like Parkinson’s and Alzheimer’s.

Inducible nitric oxide, or iNOS, is produced by cells of the immune system called macrophages. Our immune system makes use of the nitric oxide’s toxic free radical–generating capacity to kill invading pathogens like viruses and bacteria. But unlike eNOS and nNOS, which produce nitric oxide on demand for seconds, or minutes at the most, iNOS is able to chronically stimulate the production of nitric oxide for hours or even days.

Although nitric oxide is a potential free radical regardless of where and how it’s produced, nitric oxide produced by the immune system (in macrophages via iNOS) may be particularly apt to inflict dangerous collateral damage to the tissues with which it comes in contact. As the name inducible nitric oxide synthase indicates, the activity of iNOS is greatly increased under conditions of stress or trauma. It’s now thought that many of the potentially harmful effects of NO may be due to the excess nitric oxide produced from iNOS in the macrophages.

In this edition of the Integrated Supplements Newsletter, we’ll begin by focusing on nitric oxide’s role in the cardiovascular system. We’ll see precisely why trying to “boost” nitric oxide levels via the indiscriminate intake of nitric oxide precursors isn’t advisable. Instead, we’ll find that nitric oxide modulation is akin to performing a tune–up on a high–performance engine, and that we’ll need to make subtle, calculated adjustments to keep our nitric oxide metabolism running smoothly. Given what is now known about nitric oxide (but which many supplement companies continue to ignore), we’ll develop a unique strategy to ensure the proper, healthy, production and metabolism of nitric oxide within the cardiovascular system.

NO and the Cardiovascular System

In recent decades, research has made it clear that all known cardiovascular risk factors (including elevated cholesterol, elevated triglycerides, elevated homocysteine, and smoking) impair nitric oxide metabolism. As such, it’s now well–accepted that disorders of nitric oxide activity underlie the development of cardiovascular disease. Decreased bioavailability of NO is not only a direct cause of the “silent killer” known as high blood pressure (as blood vessels dilate under the influence of NO), but faulty NO signaling can also lead to cell adhesion, proliferation, and ultimately, to the acceleration of arteriosclerotic lesions within the endothelium. Impaired nitric oxide activity has also been associated with insulin resistance and diabetes, and some researchers believe that nitric oxide may be the molecular key to the well–established link between diabetes and cardiovascular disease.

Study Link – Is type 2 diabetes mellitus a vascular disease (atheroscleropathy) with hyperglycemia a late manifestation? The role of NOS, NO, and redox stress.

Quote from the above study:

Cardiovascular disease accounts for at least 85 percent of deaths for those patients with type 2 diabetes mellitus (T2DM). Additionally, 75 percent of these deaths are due to ischemic heart disease. . . The vulnerable three arms of the eNOS reaction responsible for the generation of eNO is discussed in relation to the hypothesis: (1) The L–arginine substrate. (2) The eNOS enzyme. (3) The BH4 cofactor.

In the early days of nitric oxide research (which wasn’t all that long ago), scientists logically assumed that the nitric oxide precursor, the amino acid arginine, when added to the diet, would increase levels of nitric oxide. They therefore reasoned that supplying the body with large amounts of arginine would likely restore proper vascular function (including vasodilation). This hypothesis was often validated in animal studies, and even in some short–term human studies:

Study Link – Oral L–arginine improves endothelium–dependent dilation in hypercholesterolemic young adults.

Quote from the above study:

After oral L–arginine, plasma L–arginine levels rose from 115+/–103 to 231+/–125 micromol/liter (P<0.001), and [ endothelium–dependent dilation] improved from 1.7+/–1.3 to 5.6+/–3.0% (P<0.001).

But as longer–term studies on supplemental arginine began to be conducted in patients with pre–existing heart disease, a seemingly strange trend began to emerge. In many of these studies, the patients taking arginine often fared notably worse than those not taking the amino acid. One important trial even had to be stopped prematurely because of an increase in death in the group taking arginine supplements:

Study Link – L–Arginine Therapy in Acute Myocardial Infarction The Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) Randomized Clinical Trial.

Quote from the above study:

6 participants (8.6%) in the L–arginine group died during the 6–month study period vs none in the placebo group (P = .01). Because of the safety concerns, the data and safety monitoring committee closed enrollment. . . L–Arginine, when added to standard postinfarction therapies, does not improve vascular stiffness measurements or ejection fraction and may be associated with higher postinfarction mortality. L–Arginine should not be recommended following acute myocardial infarction.

Study Link – L–Arginine Supplementation in Peripheral Arterial Disease – No Benefit and Possible Harm

Quote form the above study:

Although absolute claudication distance improved in both L–arginine– and placebo–treated patients, the improvement in the L–arginine–treated group was significantly less than that in the placebo group (28.3% versus 11.5%; P=0.024). . . As opposed to its short–term administration, long–term administration of L–arginine is not useful in patients with intermittent claudication and PAD.

Study Link – Dietary Supplementation With L–Arginine Fails to Restore Endothelial Function in Forearm Resistance Arteries of Patients With Severe Heart Failure.

Study Link – Oral L–Arginine in Patients With Coronary Artery Disease on Medical Management.

Quote from the above study:

Oral L–arginine therapy does not improve NO bioavailability in CAD patients on appropriate medical management and thus may not benefit this group of patients.

In retrospect, it’s not surprising that adding additional arginine to the diet of people with cardiovascular disease often produced negative results. The reason is that, whatever the underlying causes of nitric oxide dysfunction in heart disease, one thing’s for certain – it is NOT due to an arginine deficiency (as arginine is abundantly supplied in the vast majority of diets).

It’s likely that individuals with pre–existing heart disease (or a tendency towards heart disease) suffer from disorders involving several of the enzymes and cofactors which are needed to convert arginine into nitric oxide efficiently. In other words, if nitric oxide production is faulty, then adding arginine to the diet is destined to make matters worse in the long–run, as was found in the above studies. It’s highly likely that overwhelming the nitric oxide–producing system with supplemental doses of arginine may actually impair nitric oxide production, and lead to the production of other, more harmful substances – even in healthy people (we’ll see exactly how this phenomenon takes place later).

ADMA – The First Clue

As supplementing the diet with additional arginine produced many unpredictable and harmful effects, researchers began to wonder what factors could be responsible for impairing nitric oxide production in those suffering from cardiovascular disease and diabetes. One current suspect is an arginine analog called asymmetrical dimethyl arginine, or ADMA, for short. Acting as arginine’s “evil twin”, so to speak, ADMA can “tie up” nitric oxide synthase enzymes and can significantly inhibit NO production. People with heart disease and diabetes almost always exhibit very high levels of ADMA, and ADMA has proven to be a very strong independent risk factor for cardiovascular disease and insulin resistance:

Study Link – Risk of acute coronary events and serum concentration of asymmetrical dimethylarginine.

Quote from the above study:

In an analysis of men who did not smoke, those who were in the highest quartile for ADMA (>0.62 μ mol/L) had a 3.9–fold (95% CI 1.25–12.3, p=0.02) increase in risk of acute coronary events compared with the other quartiles. Our findings suggest that ADMA is a predictor of acute coronary events.

Elevated ADMA levels have even been implicated in erectile dysfunction, a finding which isn’t terribly surprising considering the role of nitric oxide and vasodilation in facilitating the erectile response. Given how important proper NO metabolism is to cardiovascular health, researchers now believe that erectile dysfunction may be among the earliest physical manifestations of heart disease:

Study Link – Elevation of asymmetrical dimethylarginine (ADMA) and coronary artery disease in men with erectile dysfunction.

Quote from the above study:

As elevation of ADMA has been found to be associated with many risk factors for both CAD [coronary artery disease] and ED [erectile dysfunction], our data provide further strong evidence for the close interrelation of CAD and ED. Determination of ADMA may help to identify underlying cardiovascular disease in men with ED.

Where Does ADMA Come From?

In simple terms, ADMA is a byproduct of protein metabolism. Healthy people are usually able to metabolize and eliminate it properly, but in aging and disease, ADMA levels tend to rise. Because kidney disease patients excrete protein metabolites like ADMA less efficiently than healthy individuals, ADMA levels are known to be particularly high in those with kidney disease. And because ADMA is able to increase heart disease risk by interfering with NO production, an elevated ADMA level has been proposed to be the key “non–traditional” risk factor for heart disease in those with kidney disease. In other words, even kidney patients with normal cholesterol, blood pressure, and triglycerides are still very much prone to heart disease simply because of their elevated levels of ADMA.

In patients with heart disease and/or diabetes, but without overt kidney disease, it’s a little more difficult to say exactly why ADMA levels are almost invariably elevated. We do know, however, that the enzyme which breaks down ADMA, called dimethylarginine dimethylaminohy­drolase, or DDAH, is known to be particu­larly susceptible to oxidative damage in­flicted by known cardiovascular toxins like oxidized cholesterol, oxidized polyun­saturated fatty acids, and homocysteine.

For many months now, we at Integrated Supplements have been warning you of the dangers of oxidized cholesterol – found in many processed cholesterol–containing foods and powders, or produced in the body under conditions of oxidative stress. Researchers have recently shown that oxidized cholesterol caused a much greater elevation in ADMA levels than native, unoxidized cholesterol, due to oxidized cholesterol’s (oxLDL) unique ability to impair DDAH function.

Study Link – Novel Mechanism for Endothelial Dysfunction. Dysregulation of Dimethylarginine Dimethylaminohydrolase.

Quote from the above study:

The addition of oxLDL or TNF–a to ECV304 significantly increased the level of ADMA in the conditioned medium. The effect of oxLDL or TNF–a was not due to a change in DDAH expression but rather to the reduction of DDAH activity.

And the following study showed that a lipid peroxidation product produced from the omega–6 fat linoleic acid, called 4–HNE, significantly impaired nitric oxide production by interfering with DDAH activity. The effect was only partially reversed by arginine, but completely reversed by supplying increased amounts of DDAH along with antioxidants:

Study Link – Role of DDAH–1 in lipid peroxidation product–mediated inhibition of endothelial NO generation.

Quote from the above study:

We show that the lipid hydroperoxide degradation product 4–hydroxy–2–nonenal (4–HNE) causes a dose–dependent decrease in NO generation from bovine aortic endothelial cells, accompanied by a decrease in DDAH enzyme activity. The inhibitory effects of 4–HNE (50 µM) on endothelial NO production were partially reversed with L–Arg supplementation (1 mM). Overexpression of human DDAH–1 along with antioxidant supplementation completely restored endothelial NO production following exposure to 4–HNE (50 µM). These results demonstrate a critical role for the endogenous methylarginines in the pathogenesis of endothelial dysfunction. Because lipid hydroperoxides and their degradation products are known to be involved in atherosclerosis, modulation of DDAH and methylarginines may serve as a novel therapeutic target in the treatment of cardiovascular disorders associated with oxidative stress.

Study Link – Lipid peroxidation and nitric oxide inactivation in postmenopausal women.

Quote from the above study:

NO inactivation and the increase in lipid peroxidation may contribute to endothelial dysfunction and to the greater risk for atherosclerosis in postmenopausal women.

And, illustrating just how far–reaching the effects of lipid peroxide–induced disruption of nitric oxide metabolism can be, patients suffering from major depression have been shown to exhibit elevated levels of 4–HNE, decreased activity of DDAH and subsequently, increased levels of ADMA, and decreased plasma nitric oxide.

Study Link – Increased (E)–4–hydroxy–2–nonenal and asymmetric dimethylarginine concentrations and decreased nitric oxide concentrations in the plasma of patients with major depression. 

Quote from the above study:

There is an increase in circulating HNE in major depression. HNE inactivates the cysteine residue in the active site of endothelial DDAH leading to the accumulation of ADMA in the circulation. The ADMA then decreases the production of eNOS. This could reduce the amount of NO diffusing from cerebral blood vessels to nearby neurons and influence the release of neurotransmitters. ADMA also constricts cerebral blood vessels and may contribute to the decreased regional perfusion in major depression. The accumulation of ADMA could explain the increased risk of CHD in major depression. The preservation of DDAH activity and the reduction of ADMA accumulation may represent a novel therapeutic approach to the treatment of major depression.

In the above study, we also find that the potent cellular antioxidant glutathione was able to significantly reduce the level of lipid peroxides and protect the damage inflicted on the DDAH enzyme:

The effects of HNE on DDAH activity were significantly attenuated by the addition of glutathione (P<0.0001).

Taken together, these studies give us good reason to believe that the fundamental disorder of nitric oxide bioavailability seen in aging and disease is due to oxidative stress – particularly oxidative stress driven by products of lipid peroxidation (i.e. oxidized fat and cholesterol).

And researchers in the field are beginning to come to this same conclusion:

Article Link – When the endothelium cannot say ‘NO’ anymore.

Quote from the above article:

The mechanism by which ADMA is elevated in some patients may relate to oxidative stress. ADMA is inactivated by an enzyme named dimethylarginine dimethylaminohydrolase (DDAH); most investigators agree that DDAH plays an important role in the regulation of ADMA levels. DDAH activity is downregulated by oxidative stress, as it is associated with high cholesterol, high glucose, and high homocysteine levels. In these settings, accumulation of ADMA can be prevented by addition of antioxidants in experimental models. Inhibition of DDAH, in turn, leads to elevated ADMA levels, which in turn promote further generation of oxidants, possibly by uncoupling NO synthase. This vicious circle provides an integrative explanation for the interrelation between lack of NO, excess of oxygen–derived free radicals, and progression of vascular lesion formation.

A Nutritional Plan of Attack

To lower our level of oxidative stress, reducing our intake of oxidized cholesterol (from cholesterol–containing powders like powdered eggs, powdered cheese, and whey protein concentrate), as well as dramatically reducing our intake of dietary polyunsaturated fatty acids (omega–6– and omega–3–containing fats) is the only reasonable place to start. In addition, it is likely prudent to supplement with known inhibitors of lipid peroxidation, like Vitamin E, coenzyme Q10 and lipoic acid.

As noted, the above study on nitric oxide and depression showed that the cellular antioxidant, glutathione, significantly reduced the harmful effects of HNE on DDAH, so a supplement of undenatured whey protein isolate (which contains the “building blocks” of glutathione) along with the mineral selenium (also important for glutathione production) are likely to be very helpful as well.

Note: For more information on the role of lipids in oxidative stress, see the November and December 2007 issues of the Integrated Supplements Newsletter.

Homocysteine and Nitric Oxide

In addition to byproducts produced from unsaturated fat and cholesterol, the protein–derived substance, homocysteine, has also been shown to be an important contributor to the burden of oxidative stress. Homocysteine is an amino acid produced in high amounts due to the inefficient metabolism of the amino acid methionine, and elevated homocysteine levels have increasingly been implicated as a major heart disease risk factor in recent decades. If homocysteine does, in fact, cause an elevation in ADMA (and a subsequent decrease in NO production), as is shown in the following study, this would clearly lend molecular–level support to the homocysteine hypothesis of heart disease.

Study Link – Homocysteine Impairs the Nitric Oxide Synthase Pathway Role of Asymmetric Dimethylarginine.

Quote from the above study:

Homocysteine post–translationally inhibits DDAH enzyme activity, causing ADMA to accumulate and inhibit nitric oxide synthesis. This may explain the known effect of homocysteine to impair endothelium–mediated nitric oxide–dependent vasodilatation.

Vitamins B6, B12, and folic acid can reliably reduce homocysteine, which seems to be an important piece of the puzzle given what we now know about homocysteine’s role in impairing nitric oxide production. Folic acid in particular may play several roles in ensuring proper nitric oxide metabolism (more on this later).

And as we look beyond ADMA and DDAH, deeper into the various pathways involved in nitric oxide metabolism, we begin to see yet again, that oxidative stress is the common thread responsible for disrupting all of them.

Nitric Oxide, Superoxide, and Peroxynitrite

As we outlined in the previous Integrated Supplements Newsletter, nitric oxide, being a gaseous chemical, often doesn’t stick around long once it’s produced. Nitric oxide is known to rapidly react with the free radical superoxide (O2–), producing the powerful oxidant, peroxynitrite (OONO–) (remember that oxidizing chemicals like superoxide and peroxynitrite are potent molecular–level drivers of oxidative stress).

Researchers now believe that much of the cellular damage associated with cardiovascular disease (and other diseases in which nitric oxide plays a major role) involves the over–production of superoxide and peroxynitrite from faulty nitric oxide metabolism. In fact, much of the reason that nitric oxide levels are low in cardiovascular disease is because, under conditions of oxidative stress, arginine is converted to these harmful oxidants instead of nitric oxide – yet another reason why supplying additional arginine to the body is wrought with potential danger.

Article Link – Nitric oxide, superoxide, and peroxynitrite: the good, the bad, and ugly.

Quote from the above article:

The direct toxicity of nitric oxide is modest but is greatly enhanced by reacting with superoxide to form peroxynitrite (ONOO–). Nitric oxide is the only biological molecule produced in high enough concentrations to out–compete superoxide dismutase for superoxide.

As we’ve seen, the oxidative stress of aging and disease can damage the fragile enzyme DDAH, causing nitric oxide’s “evil twin,” ADMA to become elevated. ADMA competes with arginine for NOS and causes a reduction in nitric oxide production.

But this isn’t even the only way in which oxidative stress can impair nitric oxide production. The synthesis of nitric oxide from NOS requires a cofactor called tetrahydrobiopterin, or BH4, for short. When BH4 is damaged under conditions of oxidative stress (i.e. when it is oxidized), NOS then converts arginine directly to superoxide, and ultimately to the harmful reducing agent, peroxynitrite. Scientists call this effect an uncoupling effect, as damage to BH4 is able to uncouple, or divert arginine synthesis away from nitric oxide and towards superoxide and peroxynitrite. In a vicious downward spiral, peroxynitrite causes the oxidation of even more BH4, and the synthesis of nitric oxide is then even further impaired.

Study Link – Oxidation of Tetrahydrobiopterin by Peroxynitrite: Implications for Vascular Endothelial Function.

Quote from the above study:

Nitric oxide and superoxide react rapidly to form peroxynitrite, which may be the reactive species responsible for many of the toxic effects of nitric oxide. Here we show that BH4 is a primary target for peroxynitrite–catalyzed oxidation because at pH 7.4, physiologically relevant concentrations of BH4 are oxidized rapidly by low concentrations of peroxynitrite. . . Thus, abnormally low levels of BH4 can promote a cycle of its own destruction mediated by nitric oxide synthase–dependent formation of peroxynitrite. This mechanism might contribute to vascular endothelial dysfunction induced by oxidative stress.

Not surprisingly then, damage to tetrahydrobiopterin has been shown to cause all of the cardiovascular risk factors associated with impaired nitric oxide bioavailability; and repairing or preventing damage to tetrahydrobiopterin represents a key strategy in restoring healthy nitric oxide production.

As an example, while it’s common knowledge that high cholesterol levels represent a threat to cardiovascular health (especially when coupled with an environment of oxidative stress, in which significant amounts of cholesterol are prone to oxidation), few people realize that (oxidized) cholesterol may do cardiovascular damage largely through its ability to damage tetrahydrobiopterin, and thus, healthy nitric oxide production. Infused tetrahydrobiopterin has been shown to counter this effect and restore endothelial function in patients with high cholesterol:

Study Link– Tetrahydrobiopterin restores endothelial function in hypercholesterolemia.

Quote from the above study:

In hypercholesterolemia, impaired nitric oxide activity has been associated with increased nitric oxide degradation by oxygen radicals. Deficiency of tetrahydrobiopterin, an essential cofactor of nitric oxide synthase, causes both impaired nitric oxide activity and increased oxygen radical formation. . . this study demonstrates restoration of endothelial dysfunction by tetrahydrobiopterin suppletion in hypercholesterolemic patients.

It’s also been shown that other cardiovascular risk factors, like smoking, may do their damage by impairing tetrahydrobiopterin function as well:

Study Link – Tetrahydrobiopterin Improves Endothelium–Dependent Vasodilation in Chronic Smokers Evidence for a Dysfunctional Nitric Oxide Synthase.

Quote from the above study:

These data support the concept that in addition to the free radical burden of cigarette smoke, a dysfunctional [eNOS] due to BH4 depletion may contribute at least in part to endothelial dysfunction in chronic smokers.

And while we can’t realistically inject ourselves with tetrahydrobiopterin as was done in the above studies, there may be several nutritional strategies which will allow us to optimize the function of tetrahydrobiopterin within our bodies.

Supplementation with the well–known antioxidant, vitamin C, has been shown to protect tetrahydrobiopterin from oxidation, and to restore proper NOS activity:

Study Link – Long–Term Vitamin C Treatment Increases Vascular Tetrahydrobiopterin Levels and Nitric Oxide Synthase Activity.

Quote from the above study:

In vivo, beneficial effect of vitamin C on vascular endothelial function appears to be mediated in part by protection of tetrahydrobiopterin and restoration of eNOS enzymatic activity.

Nitrate Tolerance – More Clues on The Importance of Tetrahydrobiopterin

The nitric oxide–boosting drug, nitroglycerin, has been used for over a century as a vasodilator in coronary artery disease, but a troubling phenomenon, called nitrate tolerance, almost invariably arises with the drug’s long–term use. Researchers have wondered for years why it is that nitroglycerin quickly loses its efficacy, and many theories have been proposed to explain this occurrence. The most likely scenario appears to be that nitroglycerin gradually increases the formation of reactive oxygen species (or, ROS – the molecular–level drivers of oxidative stress) by impairing the bioavailability of tetrahydrobiopterin. Two of the ROS produced in the development of nitrate tolerance are the aforementioned superoxide and peroxynitrite radicals, which, as we’ve seen, further impair nitric oxide production in a vicious downward spiral. Ironically, considering the fact that nitrate drugs are so commonly used as short–term treatments for heart disease symptoms, nitric oxide drugs are known to increase mortality in those with existing heart disease; and the production of superoxide and peroxynitrite from nitric oxide helps to explain why:

Study Link – Long–term nitrate use may be deleterious in ischemic heart disease: A study using the databases from two large–scale postinfarction studies. Multicenter Myocardial Ischemia Research Group.

Quote from the above study:

The Cox analyses with all the variables retained revealed that nitrates were associated with a significantly increased mortality risk (MSMI: hazard ratio 3.78, P =.011; MDPIT: hazard ratio 1.61, P =.019) in patients who had recovered from an acute coronary event. . . These analyses raise concern about the potential adverse effects of long–acting nitrate therapy in chronic coronary disease.

It’s worth noting, too, that the phenomenon of nitrate tolerance – where a nitric oxide boosting substance “works” in the short–term, but is harmful in the long–term – parallels many of the same surprisingly harmful effects noticed in long–term studies where arginine was administered as a nitric oxide precursor. Many nitric oxide–boosting products are often “cycled,” or taken for relatively short periods of time, with a subsequent “layoff” of arbitrary duration. But, if these products “stop working” with continued use (as empirical evidence indicates is indeed the case), it’s fair to assume that the arginine they contain is no longer being converted to nitric oxide efficiently, and is instead being converted into harmful superoxide and peroxynitrite. No supplement company can say with any certainty precisely when this toxic phenomenon begins, or whether “cycling” the product makes it less harmful in the long–term. Thus it’s probably safe to say that the more a person consumes supplemental arginine or nitric oxide–boosting supplements (cycled or not), the greater the potential harm he or she is doing to his or her body.

But, of course, even those of us not consuming nitrate drugs or nitric oxide–boosting supplements can still learn a valuable lesson from what is now known about nitrate tolerance.

If progressive damage to tetrahydrobiopterin (both by nitric oxide itself and its ROS metabolites) is responsible for nitrate tolerance, then many of the same strategies which help to prevent nitrate tolerance may do so by protecting tetrahydrobiopterin (which is our goal as well). Studies show that this is, in fact, the case.

Vitamin C has been used with success to attenuate nitrate tolerance:

Study Link – Randomized, double–blind, placebo–controlled study of the preventive effect of supplemental oral vitamin C on attenuation of development of nitrate tolerance.

Quote from the above study:

These results indicate that combination therapy with vitamin C is potentially useful for preventing the development of nitrate tolerance.

And folic acid, a nutrient which may be able to “pinch hit” for tetrahydrobiopterin, has been shown to prevent nitroglycerin–induced nitrate tolerance as well:

Study Link – Folic Acid Prevents Nitroglycerin–Induced Nitric Oxide Synthase Dysfunction and Nitrate Tolerance.

Quote from the above study:

Our data demonstrate that supplemental folic acid prevents both nitric oxide synthase dysfunction induced by continuous [nitroglycerin] and nitrate tolerance in the arterial circulation of healthy volunteers. We hypothesize that the reduced bioavailability of tetrahydrobiopterin is involved in the pathogenesis of both phenomena. Our results confirm the view that oxidative stress contributes to nitrate tolerance.

And, beyond its role in nitrate tolerance, we find several unique roles of folic acid in ensuring proper NO production and cardiovascular health. The active form of folic acid, known as 5–methyltetrahydrofolate, has been shown to prevent the vascular disruption caused by high cholesterol:

Study Link – 5–Methyltetrahydrofolate, the Active Form of Folic Acid, Restores Endothelial Function in Familial Hypercholesterolemia.

Quote from the above study:

These results show that the active form of folic acid restores in vivo endothelial function in FH. It is suggested from our in vitro experiments that this effect is due to reduced catabolism of NO.

Folic acid is also known to play a role in reducing levels of the previously–mentioned cardiovascular toxin, homocysteine. And homocysteine has been shown to inhibit tetrahydrobiopterin functioning:

Study Link – Homocysteine induces oxidative stress by uncoupling of no synthase activity through reduction of tetrahydrobiopterin.

Quote from the above study:

The results show that the oxidative stress and inhibition of NO release induced by homocysteine depend on eNOS uncoupling due to reduction of intracellular tetrahydrobiopterin availability.

Tetrahydrobiopterin and Depression

It’s also interesting to note that, in addition to its role in producing nitric oxide, tetrahydrobiopterin is also a known co–factor in the production of the neurotransmitters noradrenalin, serotonin, and dopamine.

We saw previously how lipid peroxides can impair proper nitric oxide production; and we referenced studies in which depressed patients were shown to exhibit elevated lipid peroxide levels and decreased nitric oxide levels in their plasma.

Other studies show that reduced availability of tetrahydrobiopterin may not only impair nitric oxide production, but also the production of important brain chemicals (called monoamines in the quote below) in depression.

Study Link – The role of pterins in depression and the effects of antidepressive therapy.

Quote from the above study:

As a raised N:B ratio implies failure to convert neopterin to biopterin, it is possible that reduced availability of tetrahydrobiopterin, the essential cofactor for the formation of noradrenaline, serotonin and dopamine, may exert rate–limiting control over the synthesis of monoamines implicated in the pathogenesis of depressive illness.

Add to this the fact that depression is very strongly correlated with the development of heart disease:

Study Link – Depression as a predictor for coronary heart disease. A review and meta–analysis.

Quote from the above study:

It is concluded that depression predicts the development of [coronary heart disease] in initially healthy people. The stronger effect size for clinical depression compared to depressive mood points out that there might be a dose–response relationship between depression and [coronary heart disease].

And it’s tempting to theorize that disorders of tetrahydrobiopterin function, leading to both impaired nitric oxide function, and impaired neurotransmitter synthesis, may act as a common biological thread tying together both heart disease and depression.

Unlike the symptoms of heart disease, the burden of psychological depression often manifests during the first three or four decades of life – so even young people who are not often concerned with their heart disease risks should still take note of the research presented here. And considering that psychological depression is not only a major health challenge in and of itself, but is also a clear warning sign of impending cardiovascular disease, we can clearly see how valuable integrated and biologically sound nutritional strategies are if we can indeed combat both disorders simultaneously.

As is so common in biology, addressing fundamental defects and nutrient imbalances on a cellular and molecular level, imparts a beneficial “ripple effect” throughout the entire body, whereas treating merely symptoms (with pharmaceuticals, and the “wrong” nutrients) often leads to a whole host of negative side effects.

Further Neutralizing ROS

Many of the nutrients we’ve already mentioned have potent antioxidant and cell–protective effects, and synergistically, these nutrients work together to ensure proper nitric oxide production at each step of the biological “assembly line.”

To Review:

Nutrients to prevent lipid peroxidation and to lower ADMA by preventing oxidative damage to DDAH:

• Vitamin E

• Lipoic Acid

• Whey Protein Isolate

• Selenium

Nutrients for lowering homocysteine levels:

• Folic Acid

• Vitamin B–6

• Vitamin B–12

• Trimethylglycine

Nutrients for protecting tetrahydrobiopterin

• Vitamin C

• Folic Acid

And in addition to these nutrients, several others may play important roles in ensuring healthy nitric oxide metabolism within the cardiovascular system and beyond. Plant chemicals like polyphenols and flavanols (found in such foods as tea, wine, and chocolate), may be able to scavenge superoxide and peroxynitrite radicals, potentially neutralizing these reactive oxygen species before they can trigger NOS uncoupling and the downward spiral of faulty nitric oxide metabolism.

Of course, even though polyphenols are able to quickly deactivate ROS in vitro (in a test tube), there’s still some debate as to how well these plant chemicals do so within our bodies. Our livers usually do an excellent job of “deactivating” these “foreign” chemicals before they reach the bloodstream, and surprisingly few polyphenols actually reach general circulation. It’s been proposed that either these polyphenols stimulate our own antioxidant systems (like those involving glutathione), or that the polyphenol conjugates (conjugation, or the “attachment” of one substance to another in order to improve elimination, is what the liver does to detoxify such compounds) may have antioxidant effects in and of themselves.

For more info, see:

Study Link – How should we assess the effects of exposure to dietary polyphenols in vitro?

But whatever their mechanisms of action, some plant chemicals appear to have remarkable effects on nitric oxide production in vivo (in the body) when consumed orally. The flavanols (a type of polyphenol) in unprocessed cocoa, for example, have been shown to significantly lower blood pressure via nitric oxide–mediated action.

Study Link – Flavanol–rich cocoa induces nitric–oxide–dependent vasodilation in healthy humans.

Quote from the above study:

In healthy humans, flavanol–rich cocoa induced vasodilation via activation of the nitric oxide system, providing a plausible mechanism for the protection that flavanol–rich foods induce against coronary events.

And subsequent studies by the same researchers showed that older individuals had a greater response to cocoa flavanols than younger individuals – indicating that the flavanols may be able to partly correct the decline in nitric oxide function which occurs in aging.

Study Link – Aging and vascular responses to flavanol–rich cocoa.

Quote from the above study:

Flavanol–rich cocoa enhanced several measures of endothelial function to a greater degree among older than younger healthy subjects. Our data suggest that the NO–dependent vascular effects of flavanol–rich cocoa may be greater among older people, in whom endothelial function is more disturbed.

And besides various plant polyphenols, and the vitamins we’ve already mentioned, another, more “non–traditional” antioxidant may have the unique ability to protect against the free radical damage associated with nitric oxide.

Creatine and Cardiovascular Health

Though it’s often though of only as a sports supplement useful for enhancing muscle size and strength, the high energy molecule, creatine (which, unlike some polyphenols, is very well–absorbed) has been shown to scavenge both superoxide and peroxynitrite – the molecules largely responsible for nitric oxide–induced damage.

Study Link – Direct Antioxidant Properties of Creatine.

Quote from the above study:

. . .creatine displayed a significant ability to remove [superoxide] and [peroxynitrite] when compared with controls. . . To our knowledge, this is the first evidence that creatine has the potential to act as a direct antioxidant against aqueous radical and reactive species ions.

We looked briefly at the role homocysteine plays in inhibiting DDAH, and tetrahydrobiopterin – two cofactors required for proper nitric oxide production. So, logically, lowering homocysteine will be an important part of ensuring proper nitric oxide metabolism and cardiovascular health. It’s known that the neutralization of homocysteine requires a chemical process called methylation, and that substances which donate methyl groups (CH3), such as betaine (TMG), SAMe, and choline – all available as dietary supplements – have been shown to lower homocysteine levels.

Because creatine can produce energy substrates quickly, without the metabolic demands of breaking down glucose or fatty acids for fuel, creatine can be thought of as an “emergency” energy molecule. As such, creatine is in very high demand by the most metabolically active tissues like the muscles, brain, and heart (even in non–athletes).

But the production of creatine within the body just so happens to “use up” methyl groups at an astonishingly high rate. It turns out that taking “pre–formed” creatine as a supplement (meaning, that our body doesn’t have to go through the metabolic steps of making it) spares the valuable methyl groups which would otherwise be used for creatine production – methyl groups which can then be used to neutralize homocysteine. And this effect is more than mere biological speculation – oral creatine supplements have, in fact, been shown to lower homocysteine levels significantly:

Study Link – Oral creatine supplements lower plasma homocysteine concentrations in humans.

Quote from the above study:

After four weeks of creatine supplements, [total plasma homocysteine] in [the experimental group] changed by an average of –0.9 micromol/L (range: –1.8 to 0.0), compared to an average change of +0.2 micromol/L in C (range: –0.6 to 0.9) during the same four weeks. The difference in the changes in [total plasma homocysteine] between the two groups was statistically significant (p < 0.01). CONCLUSION: Creatine supplements may be an effective adjunct to vitamin supplements for lowering [total plasma homocysteine].

Given that we must reduce the burden of superoxide, peroxynitrite, and homocysteine in order to ensure proper nitric oxide metabolism within the cardiovascular system, daily supplementation with pure creatine monohydrate probably represents one of the most physiologically sound ways to achieve all of these goals simultaneously – all the while supplying a vital energy substrate to the metabolically active cells of the muscle, brain, and heart.

In fact, it’s probably safe to say that although creatine is remarkably effective for increasing strength and energy production in athletes, those who have avoided taking creatine monohydrate because of its stigma as a mere “bodybuilding” supplement are likely to be missing out on one of the most remarkably health–promoting substances within the entire realm of nutritional supplementation.

And similarly, many people who currently think that they are taking creatine may not be. In recent years, many different types of creatine have been introduced to the nutritional supplement market, each claiming offer benefits above and beyond creatine monohydrate. In recent studies, however, two of the most heavily promoted “new” creatines, creatine ethyl ester, and a brand of “buffered” creatine, have both been shown to be vastly inferior to creatine monohydrate. In direct opposition to the marketing claims of these newfangled creatines, both creatine ethyl ester, and so–called buffered creatines have been shown to degrade into the useless byproduct creatinine much more readily than does creatine monohydrate.

Exposing the lies and misinformation surrounding creatine is best left for another newsletter, but for now, it’s important to realize that the full benefits of creatine, for cardiovascular health, or athletic improvement, can be obtained only through supplementation with pure creatine monohydrate.

The Cardiovascular System – Just The Beginning

Faulty nitric oxide metabolism has been implicated as a common denominator in various degenerative diseases including not only heart disease, but also such disorders as Alzheimer’s disease and cancer.

Fortunately, many of the dietary and supplement strategies we’ve covered here will also serve us well as we examine the effects of nitric oxide not directly related to the cardiovascular system. In the next Integrated Supplements Newsletter, we’ll take a look at nitric oxide’s role in other systems of the body, and in other disorders associated with aging. As we put all of the pieces of the nitric oxide puzzle together, the big picture of nitric oxide will begin to come into even clearer focus.

About Us: At Integrated Supplements, our goal is to bring you the wellness information and products you need to live your life to the fullest. We are dedicated to producing the highest–quality, all–natural nutritional supplements; and to educating the world on the health promoting power of proper nutrition. You can find out more by visiting: www.IntegratedSupplements.com


These statements have not been evaluated by the FDA. No Integrated Supplements product is intended to diagnose, treat, cure or prevent any disease.


What's Wrong With Nitric Oxide - Part 1


Recently, a group of surgeons performing a bowel resection operation on a young man were alarmed to notice the patient bleeding profusely during the surgery. In a frantic attempt to save the patient’s life, as one standard procedure after another failed to normalize the bleeding, the surgeons were eventually forced to perform a full blood transfusion. Though the operation was eventually a success, the physicians were perplexed, as, according to the patient’s records, he wasn’t consuming any medications which could account for such massive and life–threatening bleeding.

But, with a little biological sleuthing, it was soon found that the patient had been taking a very popular nitric oxide–boosting nutritional supplement sold as an “energy and performance igniter” for bodybuilding training. It turned out that the product contained not only various nitric oxide precursors, but several herbal nitric oxide–boosting ingredients which also happen to be potent blood thinners.

The above situation, relayed to us by one of the surgeons performing the operation, is an extreme but telling example of the dangers of accepting the nutritional supplement industry’s hype at face value. In recent years some supplement companies – especially companies specializing in bodybuilding supplements – have been able to convince their customers that there are benefits to be gained by increasing the body’s levels of the vasoactive chemical, nitric oxide. Yet, in an industry never known to let safety concerns stand in the way of profit, any mention of the potential short and long–term side effects of increasing ones nitric oxide levels has been conspicuously absent.

As a vasodilator, or, substance which dilates blood vessels, nitric oxide is known to influence blood flow as well as nutrient and oxygen delivery to cells; and some companies have speculated that increasing nitric oxide to supraphysiological levels, may result in greater increases in nutrient delivery to working muscles, and a subsequent increase in muscle growth.

Nitric oxide–boosting supplements have also been widely promoted for increasing the muscular “pump” – the localized inflammatory swelling of muscle – which is especially evident during weight training.

But the physiology of the blood vessels and blood flow (what scientists call hemodynamics) is infinitely more complicated than many within the supplement industry would have you believe. Despite the impression you may get from reading bodybuilding and fitness magazines, the study of nitric oxide as a biological chemical is still in its infancy, and looking at the existing scientific literature will give any rational, intelligent person reason to think twice about attempting to increase nitric oxide levels. Although nitric oxide is an important signaling molecule essential for life, there’s also reason to believe that purposefully stimulating its production is wrought with both short–term and long–term risks.

In this edition of the Integrated Supplements Newsletter, we’ll set the record straight on what is really known about the biological role of nitric oxide – in particular, we’ll look at its effects on vasodilation, blood flow, blood vessel integrity, bleeding, hemorrhage, septic shock, energy metabolism, exercise performance, and oxidative stress. And in part two of this series, we’ll look at the long–term effects of nitric oxide over a lifetime, and we’ll examine the integral role of nitric oxide plays as an accelerator of aging and degenerative disease.

Nitric Oxide – From Humble Beginnings

In 1867, Alfred Nobel (for whom the Nobel Prize is named), received a patent for an invention which stabilized the highly explosive chemical, nitroglycerin, by combining it with silica. The resulting malleable paste allowed the explosive power of nitroglycerine to be harnessed and controlled, and proved useful in such endeavors as mining and drilling. His invention was, of course, called dynamite.

And, in an odd coincidence, during the latter part of his life, Nobel’s physician prescribed nitroglycerin as treatment for the noted industrialist’s heart disease. Nobel, however, refused to take it, knowing from experience that the chemical caused him headaches. It would take nearly 100 years for science to discover that the factor responsible for both nitroglycerins’ role in reducing symptoms of heart disease, and Nobel’s headaches, was a vasodilating chemical called nitric oxide.

During the mid 1980’s it was discovered that nitric oxide (NO) was the mysterious biological substance which caused the dilation of blood vessels – a particularly shocking revelation considering that this gaseous chemical had previously been known as a mere industrial pollutant.

And in 1998, the Nobel Prize for medicine was awarded to a group of scientists who discovered that nitric oxide played major roles as an endogenous signaling molecule in the vascular, nervous, and immune systems of the human body. Since that time, research into the complex biological role of nitric has exploded, but still a relative newcomer to the biological scene, many questions remain as to the varied functions of this enigmatic molecule.

At first glance, much of the existing research on nitric oxide makes the chemical seem beneficial – it can indeed lower blood pressure by causing a dilation of the blood vessels, which is precisely what has made NO–boosting drugs like nitroglycerin beneficial for cardiovascular patients suffering from angina.

But as nitric oxide research has progressed, the two–faced nature of nitric oxide has begun to come to light. Some studies have surfaced indicating that certain nitric oxide–increasing therapies may have serious and potentially deadly drawbacks. In 2006, a particularly notable study using the common nitric oxide–boosting nutrient, l–arginine, in heart disease patients had to be stopped due to a dramatic increase in death in the treatment group.

Study Link – L–Arginine Therapy in Acute Myocardial Infarction – The Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) Randomized Clinical Trial.

Quote from the above study:

Because of the safety concerns, the data and safety monitoring committee closed enrollment. . . L–Arginine, when added to standard postinfarction therapies, does not improve vascular stiffness measurements or ejection fraction and may be associated with higher postinfarction mortality. L–Arginine should not be recommended following acute myocardial infarction.

And subsequent research has served to dampen the initial enthusiasm for nitric oxide–boosting therapies even further. As with most chemicals which signal cellular stress, nitric oxide can be beneficial or harmful depending upon the amount released, and the energetic state of the cells with which it comes in contact. While, in some contexts, nitric oxide may be a chemical signal for vasodilation, cell growth and adaptation, an excess of nitric oxide has been shown to cause cellular fatigue, cellular damage, and even cellular death.

So, clearly in biology, nothing is as simple as it at first seems, and this appears to be especially true of nitric oxide. As a highly reactive and potentially damaging chemical, the effects of nitric oxide have proven incredibly difficult to predict. As more studies have emerged indicating that nitric oxide–boosting nutrients may be harmful in some treatment groups, many researchers now believe that, in certain circumstances, we should actually take steps to decrease our production of nitric oxide, not increase it.

Study Link – L–Arginine Supplementation in Peripheral Arterial Disease – No Benefit and Possible Harm.

Quote form the above study:

Although absolute claudication distance improved in both L–arginine– and placebo–treated patients, the improvement in the L–arginine–treated group was significantly less than that in the placebo group (28.3% versus 11.5%; P=0.024). . . As opposed to its short–term administration, long–term administration of L–arginine is not useful in patients with intermittent claudication and PAD.

Study Link – Effects of chronic treatment with L–arginine on atherosclerosis in apoE knockout and apoE/inducible NO synthase double–knockout mice.

Quote from the above study:

This raises the possibility that L–arginine supplementation may paradoxically contribute to, rather than reduce, lesion formation by mechanisms that involve lipid oxidation, peroxynitrite formation, and NOS uncoupling.

But, even though the work of world–renowned biologists and chemists clearly shows that nitric oxide is a double edged–sword whose benefits have yet to be harnessed without risk, we need only to open the pages of any bodybuilding or fitness magazine to witness the reckless hucksters of the supplement industry touting products specifically designed to dramatically increase our nitric oxide levels. If their past track record is any indication, we can expect these companies to largely ignore the growing body of research which paints nitric oxide, and nitric oxide–boosting nutrients in a negative light, simply because such research doesn’t help them sell products.

The Products and Their Claims

The advertising for nitric oxide–boosting products in the bodybuilding realm usually centers around claims of increased blood flow to muscles, better nutrient delivery, enhanced “pumps” while training, and overall, an increase in muscular size and strength.

NO–boosting products are also sold as aids to erectile function, and (despite the above–listed studies) to support cardiovascular health. Whatever the claim or target demographic, the underlying mechanism for these products revolves around the same basic biological function – the ability of nitric oxide to dilate blood vessels.

Most nitric oxide–boosting products are formulated with various types of arginine – the amino acid from which nitric oxide is produced in the body. And although simple l–arginine supplements have been available for decades, as studies on the biological role of nitric oxide began to fill medical journals, certain enterprising individuals within the supplement industry decided to blow the dust off of this amino acid, and re–introduce it to the bodybuilding world in the form of novel arginine–containing salts like arginine alpha–ketoglutarate (AAKG) – possibly the most common ingredient in the current group of nitric oxide boosting supplements.

Because both arginine, and ketoglutarate are known to increase arginine levels in the body, it’s reasonable to believe that AAKG may increase arginine levels (and subsequently, nitric oxide) to a greater extent than l–arginine alone. But given the scientific–sounding jargon of many supplement advertisements, many people are surprised to learn that little to no research has been performed on AAKG in relation to nitric oxide levels. And as we have seen, even some studies which look at the effects of orally administered l–arginine (a relatively modest NO–booster at best), still give us reason for concern.

Dozens of other ingredients are often added to nitric oxide–boosting products including other salts of arginine as well as citrulline, an amino acid which is converted to arginine in vivo (in the body). And complicating matters even further is the common presence of compounds (especially blood thinning nutrients and herbs) which can potentially amplify the vascular effects of arginine and its metabolites. Because of this, the risk of excessive and pathological bleeding and hemorrhage is a very real concern even with the short–term usage of some nitric oxide–boosting products. But before we get too far ahead of ourselves, a little perspective on the true biological roll of nitric oxide is probably in order.

A Little Perspective on NO

Because the literature on nitric oxide is often conflicting, it’s important to sketch a bird’s eye view of its function within the body. Those attempting to sell you nitric oxide–boosting formulas often have a tendency to cherry pick the literature, showing you only studies (if they reference valid studies at all), which support their claims in limited contexts. For example, nitric oxide, as the supplement industry has so widely advertised, does indeed cause dilation of blood vessels. And this vasodilation may increase blood flow and allow the cells to temporarily produce energy more efficiently (with less oxygen consumption) under periods of stress.

But it’s important to always remember that the production of nitric oxide, and the dilation of blood vessels, is a defensive response of the body to stressful stimuli. As with all defensive responses, if the body lacks the ability to “shut off” the response, the response self–perpetuates, and the overall effects will be damaging and sometimes deadly. It’s crucial to recognize this fact, because there is often the mistaken belief that biological functions which can be harmful are under “tight control,” and that it’s nearly impossible to harm oneself with mere nutrients or nutritional supplements. But in the presence of certain stressors, we find that a great amount of damage can be done before the body is able to restore balance. As an example, we can see the quintessential illustration of the self–perpetuating nature of the nitric oxide stress response in the phenomena of sepsis and septic shock.

In the previous issue of the Integrated Supplements Newsletter, we saw how the presence of a “leaky gut” can allow bacteria and bacterial components called endotoxin to enter the bloodstream from the intestines, causing chronic systemic inflammation.

When such translocation of bacteria from the intestines into the bloodstream is significant, the condition is called sepsis, or what is often known in layman’s terms as blood poisoning. One of the bodies’ primary responses to sepsis is an increase in the production of nitric oxide. In the very short term, NO can dilate blood vessels and increase nutrient delivery to cells possibly allowing them to counter the stress by increasing their energy production. Very quickly, however, the hypotension (low blood pressure) caused by NO can lead to the exact opposite phenomenon –a dangerous decrease in blood flow to vital organs like the brain and kidneys, and an overall reduction in protective energy production throughout the body.

The vasodilating effects of NO are so strong in septic shock, that the blood vessels remain dilated despite the body’s best efforts to normalize them with vasoconstricting agents like adrenaline. The heart frantically attempts to compensate for the lowered blood pressure by pumping blood at an accelerated rate, but often, to no avail. As the heart soon weakens, blood pressure drops even further, causing blood vessels to leak, leading to bleeding (especially in the lungs, causing difficulty breathing), hemorrhage, cardiac failure, and often, death.

In relation to the surgery patient we mentioned in the introduction, and noting nitric oxide’s fundamental role in this chain of events, we see why none of the surgeons’ interventions worked to stop the young man’s bleeding and hypotension, until they supplied his body with more blood via a transfusion – sufficiently increasing blood volume (and therefore, pressure) and oxygen delivery to stop the bleeding and save his life.

Nitric oxide is so fundamental to the vicious chain of events in sepsis, that strategies for combating sepsis now often involve therapies aimed at dramatically reducing the production of nitric oxide.

Study Link – Nitric oxide in the pathogenesis of sepsis.

Quote from the above study:

In sepsis and septic shock, inflammatory mediators result in the production of increased concentrations of nitric oxide (NO) from the enzymatic breakdown of the amino acid L–arginine. The increased amounts of NO are responsible for changes in vasomotor tone, decreased vasopressor responsiveness, and decreased myocardial function, characteristic of septic insult. Therapeutic strategies designed to reduce the concentration of NO by inhibiting the action of the nitric oxide synthase enzyme, or by scavenging the excess NO, offer the potential to treat directly the vasomotor abnormalities and myocardial depression seen in sepsis and other inflammatory states.

Study Link – Circulatory failure in septic shock. Nitric oxide: too much of a good thing?

Quote from the above study:

One of the characteristic features of septic shock is profound hypotension caused by a decrease in peripheral vascular resistance. This hypotension is unusually resistant to both volume replacement and vasoconstrictor agents.

And it’s important to remember as well, that nitric oxide doesn’t just affect the blood vessels. Cells of the immune system and the nervous system also synthesize nitric oxide, and cumulatively, the nitric oxide produced by various cells can cause massive tissue damage via NO’s free radical–generating capacity.

A quote from the same study:

. . . production of large quantities of nitric oxide leads not only to haemodynamic instability but also to widespread production of nitric oxide–based free radicals which have the potential to cause considerable damage to tissues. Evidence from clinical studies supports this.

So, let’s get it straight right from the beginning: nitric oxide is an inflammatory chemical, which is produced in response to stress, injury, and trauma. Like other inflammatory chemicals, nitric oxide has a role in normal human physiology, but an excess of it, or prolonged stimulation of it is decidedly harmful. Nitric oxide synergizes with and stimulates other inflammatory chemicals, including prostaglandins, and cytokines. NO reduces blood pressure and oxygen utilization, increases lactic acid production, impairs mitochondrial energy production, promotes excitotoxicity, and causes (either directly or indirectly) various types of cell death.

And knowing that nitric oxide is able to overwhelm the body’s hemodynamic regulatory systems should make us think twice about consuming large amounts of arginine, or other nitric oxide precursors or boosters. An abundance of nitric oxide precursors in the body could make even everyday stresses (like workouts) harmful and, in rare cases, even catastrophic.

For example, it’s known that exercise weakens intestinal barrier function, and causes bacteria and endotoxin to be absorbed. Sepsis and exercise share so many inflammatory factors in common, that intense exercise has even been proposed as a model for studying sepsis.

Study Link – Sepsis and mechanisms of inflammatory response: is exercise a good model?

Study Link – Are similar inflammatory factors involved in strenuous exercise and sepsis?

Study Link – Strenuous exercise causes systemic endotoxemia.

Quote from the above study:

Eighteen triathletes were studied before and immediately after competing in an ultradistance triathlon. Their mean plasma lipopolysaccharide (LPS) concentrations increased from 0.081 to 0.294 ng/ml (P less than 0.001), and their mean plasma anti–LPS immunoglobulin G (IgG) concentrations decreased from 67.63 to 38.99 micrograms/ml (P less than 0.001).

So, we should be aware that in exercise, and in sepsis, the same principles of nitric oxide metabolism apply – the difference is merely one of degree. This, of course, is a fact which is conspicuously absent from the advertising of nitric oxide–boosting supplements, but it’s an important fact to recognize if we are to accurately assess the risks associated with these products.

Nitric Oxide and Peroxynitrite – General Toxic Effects

But it’s not simply the vasodilating effects of NO which may prove harmful in excess. As alluded to above, nitric oxide and its metabolites are also able to produce massive amounts of free radical damage – damage which has been shown to be toxic to the well–known “power plants” of the cells, the mitochondria.

As the science of biology advances, mitochondrial function is turning out to be the key to the mysteries of aging and degenerative disease. If you take nothing else from this article, let it be this:

Maintaining healthy mitochondria – mitochondria which are undamaged physically, and which produce energy efficiently – is the key to a long, energetic, happy, and disease–free life.

The energy produced by our mitochondria creates a “force field” of protection around the cell, allowing it to grow, adapt, and survive various stressors. Think of your cells as being constantly protected by an invisible electric fence, the power for which is supplied by the mitochondria – cut the power (damage or poison the mitochondria), and the cell becomes susceptible and increasingly vulnerable to all sorts of cellular stressors. The cells lose the ability to “fight back” and can no longer grow stronger and more resilient in response to stress – eventually they simply wave the white flag of defeat in response to any threat which comes along. Poison enough of these power plants and you accelerate your descent into aging, depression, atrophy, and degenerative disease.

One of the keys to the generally toxic effects of nitric oxide on the mitochondria is the NO derivative, called peroxynitrite (ONOO –). Being a gas, and a free radical, nitric oxide doesn’t stick around long once it’s produced. It rapidly reacts with surrounding molecules, especially the free radical superoxide, producing the particularly harmful oxidizing and nitrating agent, peroxynitrite.

On a cellular level, both NO and peroxynitrite have been shown to decimate mitochondrial function.

In fact, the following study and quote show clearly that NO and peroxynitrite impair mitochondrial function in almost every conceivable way – inhibiting multiple mitochondrial enzymes, chewing up antioxidants, damaging proteins, spilling redox–active iron, as well as causing lipid peroxidation, cell swelling, calcium release, and membrane permeability (all direct precursors to cell death).

Study Link – Nitric oxide and mitochondrial respiration.

Quote from the above study:

Nitric oxide (NO) and its derivative peroxynitrite (ONOO−) inhibit mitochondrial respiration by distinct mechanisms. Low (nanomolar) concentrations of NO specifically inhibit cytochrome oxidase in competition with oxygen, and this inhibition is fully reversible when NO is removed. Higher concentrations of NO can inhibit the other respiratory chain complexes, probably by nitrosylating or oxidising protein thiols and removing iron from the iron–sulphur centres. Peroxynitrite causes irreversible inhibition of mitochondrial respiration and damage to a variety of mitochondrial components via oxidising reactions. Thus peroxynitrite inhibits or damages mitochondrial complexes I, II, IV and V, aconitase, creatine kinase, the mitochondrial membrane, mitochondrial DNA, superoxide dismutase, and induces mitochondrial swelling, depolarisation, calcium release and permeability transition. . . The NO inhibition of cytochrome oxidase may also be involved in the cytotoxicity of NO, and may cause increased oxygen radical production by mitochondria, which may in turn lead to the generation of peroxynitrite. Mitochondrial damage by peroxynitrite may mediate the cytotoxicity of NO, and may be involved in a variety of pathologies.

So, in layman’s terms, nitric oxide and peroxynitrite can act as agents of wholesale cellular destruction, choking the life out of our cells at the most fundamental level. And once the cell is weakened in this way, even “normal” stresses and stimulation can become deadly to the cell.

And such damaging effects on a cellular level are easy to extrapolate to a macroscopic level as in the role of NO and peroxynitrite in degenerative disease:

Study Link – Nitric oxide and peroxynitrite in health and disease.

Quote from the above study:

Since its early description as an endothelial–derived relaxing factor, NO has emerged as a fundamental signaling device regulating virtually every critical cellular function, as well as a potent mediator of cellular damage in a wide range of conditions. . . In vivo, peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorder.

Nitric Oxide, NMDA, and Chronic Fatigue

Given what we now know about nitric oxide’s effects on cellular energy production, it seems especially strange that various nitric oxide–boosting products are being touted as energy boosters and performance enhancers. Many of these products are spiked with caffeine or creatine, both of which may impart energizing effects, but one thing’s for certain – nitric oxide itself certainly does not lead to an increase in energy production. In fact, quite the opposite is true. Some researchers have actually implicated an excess of nitric oxide production as the central metabolic defect underlying the chronic fatigue syndrome.

Without the damage caused by nitric oxide, and the subsequent drain on cellular defenses, stimulation of the excitatory NMDA receptor may simply be a normal physiological event involved in such phenomenon as memory and learning. In the presence of nitric oxide, however, uncontrolled nervous excitation, and cell death may result from the very same stimulation. Nitric oxide has been shown to be a necessary co–factor in the toxic effects of NMDA stimulation by excitatory amino acids. We’ve seen in previous Integrated Supplements Newsletters that the stimulation of the NMDA receptor is often a self–perpetuating sequence which drains cellular energy to the point of cell death.

Study Link – Nitric oxide mediates glutamate neurotoxicity in primary cortical cultures.

Quote from the above study:

We show that the nitric oxide synthase inhibitors, N omega–nitro–L–arginine (EC50 = 20 microM) and N omega–monomethyl–L–arginine (EC50 = 170 microM), prevent neurotoxicity elicited by N–methyl–D–aspartate and related excitatory amino acids. This effect is competitively reversed by L–arginine. Depletion of the culture medium of arginine by arginase or arginine–free growth medium completely attenuates N–methyl–D–aspartate toxicity. . . These data establish that NO mediates the neurotoxicity of glutamate.

Individuals with excess production of nitric oxide may suffer from NMDA over–stimulation, and may be predisposed to chronic pain, fatigue, chemical sensitivity, and they may even be especially susceptible to the negative effects of excitotoxic food additives like MSG and the artificial sweetener, aspartame.

The following study found that the amino acid citrulline (a “byproduct” of arginine’s production of nitric oxide), is consistently elevated in chronic fatigue patients.

Study Link – Levels of Nitric Oxide Synthase Product Citrulline Are Elevated in Sera of Chronic Fatigue Syndrome Patients.

Quote from the above study:

Serum citrulline levels were found to be significantly elevated in CFS patients and, in addition, there was a trend towards higher levels in CFS patients with stronger symptoms. These results provide support for the view that nitric oxide synthase activity tends to be elevated in CFS patients, thus supporting a prediction of the elevated nitric oxide/peroxynitrite theory of CFS etiology.

And it has also been proposed that the link between chronic fatigue syndrome and other related disorders stems from an elevation in nitric oxide synthesis.

Study Link – Elevated Nitric Oxide/Peroxynitrite Mechanism for the Common Etiology of Multiple Chemical Sensitivity, Chronic Fatigue Syndrome, and Posttraumatic Stress Disorder.

In relation to chronic fatigue, it’s interesting to note that chronic fatigue patients often manifest low blood pressure. It’s usually assumed that this low blood pressure has much to do with adrenal exhaustion. The thinking is that the adrenal glands of chronic fatigue patients aren’t sufficiently producing the adrenaline needed for energy and proper blood vessel tone. But if chronic fatigue patients do indeed overproduce nitric oxide, the vasodilating effect of nitric oxide could be another cause of the low blood pressure often noted in these patients.

This possibility opens up multiple avenues for treatment, and not coincidentally, the researchers who implicate nitric oxide in these disorders recommend nutrients and drugs aimed specifically at scavenging nitric oxide, lowering NMDA activity, and restoring mitochondrial function.

For example, the energizing effect of vitamin B–12 is well known, but few people realize that this effect may be due to B–12’s ability to scavenge and deactivate nitric oxide.

Study Link – Cobalamin Used in Chronic Fatigue Syndrome Therapy Is a Nitric Oxide Scavenger.

Other nutrients which may improve energy production by minimizing NO/peroxynitrite–induced damage include Co–Q10, niacinamide, magnesium and vitamin C.

What About Antioxidants?

Noting that the stimulation of nitric oxide is well–known to induce cellular and tissue damage via the free radical activity of peroxynitrite, some sellers of nitric oxide–boosting supplements have taken to formulating their products with a sprinkling of various antioxidants, supposedly acting as some sort of “damage control.”

But while the inclusion of antioxidants in these products may be somewhat beneficial, it’s unclear to what extent these antioxidants actually help counter an “artificially elevated” nitric oxide level. As for now, the inclusion of antioxidants with nitric oxide boosters (like so much else in the nutritional supplement industry) amounts to little more than simply wishful speculation.

But, it’s worth noting that some antioxidants do have unique and potentially positive effects on nitric oxide metabolism, and they may be beneficial in keeping nitric oxide levels within a normal, healthy range – assuming we don’t overwhelm the system with nitric oxide precursors or boosters.

The potent thiol (sulfur–containing) antioxidant, lipoic acid, has been shown to increase nitric oxide–mediated vasodilation in disease states, but not in healthy subjects. This effect is likely a clue that the way to ensure proper, healthy, nitric oxide production lifelong is via reducing our levels of oxidative stress – not by increasing our intake of arginine and similar nitric oxide precursors.

Study Link – Beneficial effects of α – lipoic acid and ascorbic acid on endothelium–dependent, nitric oxide–mediated vasodilation in diabetic patients: relation to parameters of oxidative stress.

Quote from the above study:

The impairment of nitric oxide (NO)–mediated vasodilation in diabetes has been attributed to increased vascular oxidative stress. Lipoic acid has been shown to have substantial antioxidative properties. . . Lipoic acid improved NO–mediated vasodilation in diabetic patients, but not in controls.

It’s known that the nitric oxide response of the blood vessels decreases in aging and disease (meaning that diseased blood vessels don’t respond to nitric oxide by dilating as effectively as healthy blood vessels do), but if, as the above study indicates, oxidative stress (and not lack of arginine) is the cause of the faulty nitric oxide response, then reducing oxidative stress is the most logical and physiologically sound solution – this is why taking arginine supplements won’t necessarily help, and is likely to do more harm, as has been shown in various studies.

Excess Nitric Oxide – Concerns in Exercise

Even people with little biological knowledge seem to understand the simplistic notion that the stress of weight training causes “damage” to the muscle, which, under ideal conditions, the body responds to by growing larger, stronger, or more efficient. Nitric oxide release is a normal response to the stress of training, and the damage which is caused by nitric oxide may be a part of the “damage” of training which the body adapts to by growing larger or stronger.

It’s conceivable that, in otherwise healthy people, and in the short–term, one of the responses to the cellular assault inflicted by nitric oxide and its metabolites may be an increase in muscle growth as a protective measure – assuming other factors like nutrition and rest are accounted for properly. But people taking nitric oxide–boosting products should know full–well, and without any ambiguity, that they are doing further damage to the body, and adding to the stress of training with these products, and not simply “supplying more nutrients to the muscle” as is commonly implied in product advertising.

Similarly, as relates to the “pump” experienced during training, this effect may indeed be partly due to increased blood flow to the muscle, but tissue swelling is a well–known to be a response to tissue damage and fatigue – and is probably not due to the simple dilation of blood vessels. In this sense, because nitric oxide does cause tissue damage and mitochondrial damage (leading to the more rapid onset of muscular fatigue), it’s fair to say that NO may stimulate a “pump” during training. But the fact that muscular swelling during exercise is largely due to a localized (and potentially harmful) inflammatory response, and not simply to increased blood flow as is sometimes implied, means that the marketers of NO–boosting products are simply spinning the science to make their advertising copy seem pleasing to an uneducated clientele.

And noting that nitric oxide decreases energy production on a cellular level, it’s interesting to look at studies which have shown significant decreases in exercise performance when the NO–precursor, arginine, was ingested – especially in endurance sports.

The following study, which looked at the effects of arginine on several metabolic markers during and after a marathon, found that arginine supplementation led to an average finish time 23 minutes longer than predicted.

Study Link – The effect of arginine or glycine supplementation on gastrointestinal function, muscle injury, serum amino acid concentrations and performance during a marathon run.

Arginine supplementation tends to fare a bit better in strength sports, but we can’t necessarily attribute this effect solely to nitric oxide. There are simply far too many metabolic fates for arginine besides NO to make such an assumption valid. Arginine, for example is a precursor to the well–known performance enhancer creatine, increased production of which could easily account for any marginal increases in strength or performance noted with arginine supplementation.

But, even in the highly “cosmetic” sport of bodybuilding, where a good pump is often just as important as improved performance, it’s hard to justify the use of nitric oxide supplements in light of the relevant research.

Unlike some unhealthy lifestyle habits, for which the repercussions manifest over decades, the negative effects of stimulating nitric oxide production can potentially be short–term and catastrophic. As we’ve seen, the threat of excessive bleeding and hemorrhage when nitric oxide is increased is very real.

Along these lines, a particularly strong warning should be made against the use of nitric oxide–boosting products for contact athletes such as football players, hockey players, and martial artists. The last thing these athletes want is high levels of nitric oxide and nitric oxide precursors running through their bloodstream during competition. If stimulated by contact, the over–production of nitric oxide could lead to excessive and uncontrollable bleeding.

The effect of nitric oxide–boosting drugs, such as nitroglycerine, on bleeding has been known for decades, and studies have shown that inhibiting the enzyme from which NO is produced, significantly shortens bleeding time.

Study Link – Effect of nitric oxide synthase inhibition on bleeding time in humans.

Quote from the above study:

These data show that systemic inhibition of NO production shortens [bleeding time] in humans.

And various other studies and reports have linked nitric oxide with excessive bleeding, cerebral hemorrhage, and hemorrhagic shock.

Study Link – Novel roles of nitric oxide in hemorrhagic shock.

Quote from the above study:

Thus, induced nitric oxide, in addition to being a "final common mediator" of hemorrhagic shock, is essential for the up–regulation of the inflammatory response in resuscitated hemorrhagic shock. Furthermore, a picture of a pathway is evolving that contributes to tissue damage both directly via the formation of peroxynitrite, with its associated toxicities, and indirectly through the amplification of the inflammatory response.

Study Link – Nitric Oxide Insufficiency, Platelet Activation, and Arterial Thrombosis

Quote from the above study:

We reported the case of a 29–year–old woman with a hypertensive crisis treated with [the nitric oxide–increasing drug] sodium nitroprusside for blood pressure control who sustained an intracerebral hemorrhage after being normotensive on therapy for 24 hours.

And, lest you think that nitric oxide–boosting nutritional supplements must somehow be safer than nitric oxide–boosting drugs, realize that the “witches’ brew” formulations of many nitric oxide–boosting supplements often contain dozens of vasoactive substances haphazardly thrown together – including shockingly potent blood–thinning agents in addition to arginine substrates.

One such blood–thinning ingredient is rutaecarperine from the herb called evodia rutaecarpa. On a molar basis, retaecarperine has been shown to prolong bleeding time twice as long as aspirin.

Study Link – Antithrombotic effect of rutaecarpine, an alkaloid isolated from Evodia rutaecarpa, on platelet plug formation in in vivo experiments.

Quote from the above study:

On a molar basis, rutaecarpine was approximately twofold more potent than aspirin at prolonging the occlusion [bleeding] time.

So, although the “blood–thinning” effect of nitric oxide and related substances is often simply assumed to be beneficial, such simply isn’t the case. Certainly, blood with an excessive tendency to clot is a risk factor for cardiovascular disease in the long–term, but, on the other side of the coin, blood which doesn’t clot sufficiently can be even more acutely dangerous in situations where bleeding is a possibility.

Very similarly, high blood pressure is a known risk factor for cardiovascular disease, but as we’ve seen, low blood pressure, as a result of excessive nitric oxide production, can often be deadly in certain stressful situations. Clearly, balance is the key, and nitric oxide stimulation can play a major role in upsetting this balance greatly – even in the short–term.

In part two of our series on nitric oxide, we’ll look at the long–term role nitric oxide plays in various degenerative diseases. But hopefully, the research we’ve presented here on the general and shorter–acting effects of NO is already sufficient enough to allow any rational person to look at nitric oxide–boosting products in a whole new light.

With their typical reckless abandon, and biological shortsightedness, the sellers of nitric oxide–boosting supplements are asking you to accept far more risk than you may realize, while offering you far fewer benefits than they promise. But, in many ways, with nitric oxide–boosting products, it’s the same formula we see far too often in this industry – wild baseless speculation, is backed by cherry picked research, and stunningly ignorant oversimplifications of complex biological processes are proffered as the latest in “cutting edge science.”

If you value your health, your longevity, your performance, your intellect, or even simply the money you’ve worked so hard for, you’ll let the current nitric oxide fad run its course – without becoming one of its casualties.

About Us: At Integrated Supplements, our goal is to bring you the wellness information and products you need to live your life to the fullest. We are dedicated to producing the highest–quality, all–natural nutritional supplements; and to educating the world on the health promoting power of proper nutrition. You can find out more by visiting: www.IntegratedSupplements.com


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