5 posts categorized "Protein"

March 03, 2012

Whey Protein Q&A - Whey Protein Isolate Versus Whey Protein Concentrate Part 3 - Glycation Products in Protein Supplements

BlogProQAC Q. What are glycation products?

A. Glycation products are altered protein structures resulting from the chemical interaction of proteins, sugars, and fats.  Glycation products can be produced both in our foods and in our bodies as well.  When the chemical changes proceed far enough, the resulting structures are called advanced glycation endproducts, or, AGEs, for short. Various glycation products and AGEs have been found to be consistently elevated in the body under conditions of aging and disease.

For example, a particular glycation product, called furosine, has been shown to be elevated in patients with Alzheimer’s disease and diabetes:

Study Link – Plasma protein glycation in Alzheimer's disease.

Quote from the above study:

Recent studies have suggested that formation of advanced glycation end–products (AGEs) in some brain proteins could be associated with Alzheimer's disease…Protein glycation was evaluated in plasma with a highly specific HPLC–UV technique, using furosine, which is the acid hydrolysis product of epsilon–deoxy–fructosyl–lysine Plasma furosine was almost two times higher in subjects with Alzheimer's disease (p<.005) than in controls, but still 50% lower than in diabetic patients (P<.02).

And similar to the glycation phenomenon which occurs in our body under the conditions of aging, certain types of food processing are known to result in the production of high amounts of furosine as well. 

As relates specifically to protein powders, the following study tested the furosine content of several commercially available sports supplements produced using milk based ingredients like whey protein isolate, whey protein concentrate, and casein. The furosine levels the researchers found was shockingly high in products which contained whey protein concentrate:

Study Link – Assessing nutritional quality of milk–based sport supplements as determined by furosine.

Quote from the above study:

Furosine content ranged from 2.8 to 1125.7 mg/100 g protein in commercial sport supplements being usually lower in samples containing mainly whey protein isolates or casein, as compared with whey protein concentrates. It is estimated that 0.1–36.7% of the lysine content is not available in this type of products. The use of high quality ingredients for the manufacture of sport supplements reveals important, since it could be the major source of protein intake of certain group of consumers in high or moderate training regime. Furosine is an appropriate indicator to estimate the nutritional quality of sport supplements. A reference value of 70 mg furosine/100 g protein content in dried sport supplements could be set up for controlling the quality of milk–based ingredients used in the formulation. Samples with higher levels are suspected of use of low quality milk–based ingredients or inappropriate storage conditions.

Knowing that glycation products formed in our body may be partly responsible for the degenerative effects of aging, and knowing that glycation products have repeatedly been associated with various degenerative diseases, it’s logical to think that perhaps eating these same glycated proteins may not be such a great idea if we value our long–term health.

Q.  It’s often assumed that high protein intakes aren’t particularly harmful because the body will simply rid itself of the excess.  Is this true?

A.  Some proteins which have been altered by the industrial processes we’ve been describing are likely to have vastly different toxicity profiles relative to minimally-processed protein foods.  In other words, high protein intakes, per se, aren’t likely to be problematic, but high amounts of protein supplements and industrially-processed proteins may be. 

As a bit of background, mainstream nutritionists and doctors often maintain that the average American diet contains sufficient (and, perhaps, too much) protein, and that even the protein requirements of hard-training athletes are only slightly above those of sedentary individuals.  These same experts sometimes also warn that, not only is high protein consumption unnecessary, but that excess protein intake could tax kidney function, and may, thus, actually be harmful.  The bodybuilding, fitness, and supplement communities, however, have largely ignored these warnings, citing evidence of cultures consuming high protein intakes without apparent harm. 

Slowly, some within the medical community have begun to realize that their peers may have previously underestimated the importance of protein in a healthy diet geared towards fat loss and muscle growth or maintenance.  Perhaps spurred by the low-carb and high-protein diet craze of several years ago, the value of high protein intakes has received increasing justification from the medical community.  It’s common now, in fact, to see various protein-centric diet books - and their accompanying protein-containing snack bars and concoctions - peddled by medical doctors.

But, almost universally, both the medical and fitness crowds completely ignore the uniquely toxic effects of the denatured and glycated proteins commonly found in nutritional supplements.  

As protein supplements and protein-fortified foods have become more widely used across various segments of society, it’s likely that the consumption of glycated and industrially-denatured proteins has increased commensurately.  As such, because protein supplements may have completely unique toxicity profiles relative to traditional protein-containing foods, the health effects of industrially-denatured and glycated proteins should be more widely addressed.

While the human body does possess mechanisms to rid the body of excess protein, “getting rid” of glycated proteins is exactly what the body does not do efficiently – and this is what makes many protein–based nutritional supplements uniquely toxic relative to minimally–cooked protein–rich foods.  We’ve already seen, for example, how altered protein structures may promote the growth of harmful intestinal bacteria.  In addition, eating denatured proteins and glycation products (as many users of protein powder, protein bars and ready–to–drink protein shakes unknowingly do), has been shown to add to the AGE burden of the body, and may be particularly detrimental to kidney function:

Study Link – Advanced glycation endproducts (AGEs) as uremic toxins.

Quote from the above study:

Dietary AGEs may contribute significantly to the total AGE load of the body, particularly in uremia.

So, while high intakes of food-based proteins have not been shown to impair kidney function in healthy individuals, there is significant reason to believe that high intakes of many common protein supplements may.

It has been found, for example, that eating glycated protein causes a major increase in systemic inflammation – including inflammatory disease markers such as C–reactive protein, even in healthy subjects:

Study Link – Diet–derived advanced glycation end products are major contributors to the body's AGE pool and induce inflammation in healthy subjects.

Quote from the above study:

Advanced glycation end products (AGEs) are a heterogeneous group of compounds that form continuously in the body. Their rate of endogenous formation is markedly increased in diabetes mellitus, a condition in which AGEs play a major pathological role. It is also known, however, that AGEs form during the cooking of foods, primarily as the result of the application of heat. This review focuses on the generation of AGEs during the cooking of food, the gastrointestinal absorption of these compounds, and their biological effects in vitro and in vivo. We also present preliminary evidence of a direct association between dietary AGE intake and markers of systemic inflammation such as C–reactive protein in a large group of healthy subjects. Together with previous evidence from diabetics and renal failure patients, these data suggest that dietary AGEs may play an important role in the causation of chronic diseases associated with underlying inflammation.

AGEs are also known to damage blood vessels, and many researchers have implicated AGEs as the major factors responsible for the vascular damage associated with kidney disease and diabetes. Building logically from this, some researchers have proposed a very plausible connection between the ingestion of glycation products in foods and the development of diabetes and subsequent diabetic complications like kidney disease:

Study Link – Possible link of food–derived advanced glycation end products (AGEs) to the development of diabetes.

Quote from the above study:

The formation and accumulation of advanced glycation end products (AGEs) have been known to progress at an accelerated rate under diabetes, and there is accumulating evidence that AGEs play a role in the development of diabetes by inducing islet beta cell damage and/or insulin resistance. Further, there are several animal studies to suggest that dietary AGEs are involved in insulin resistance, visceral obesity and the development of diabetes.

So, despite the common misconception that denatured and glycated proteins are merely inert, or “wasted,” the evidence is overwhelmingly clear that they are, instead, often mildly and cumulatively toxic.

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February 11, 2012

Whey Protein Q&A - Whey Protein Isolate Versus Whey Protein Concentrate Part 1 - Oxidized Cholesterol

BlogProQACQ. How is Whey Protein Isolate different from Whey Protein Concentrate?

A. Whey protein concentrate contains between 34% and 80% protein, and contains relatively high levels of lactose, fat, and cholesterol.  Whey protein isolate, on the other hand, contains 90% or greater protein by weight, and negligible levels of lactose, fat, and cholesterol.

Because whey protein concentrates are often used as filler ingredients in animal feed, baked goods, and processed dairy products, great care is often not taken to protect the delicate whey protein structures in the production of whey protein concentrate.  As a result, high levels of denatured and glycated proteins are often formed when whey protein concentrate is produced.

These denatured and glycated proteins (i.e., altered protein structures, and altered protein structures formed when proteins interact with sugars and lipids) greatly compromise the nutritional quality of whey protein concentrate, and may even prove harmful.

Properly-prepared whey protein isolates, on the other hand, are produced using selective filters which rid the product of essentially all denatured and glycated proteins (as well as lactose, fat, and cholesterol).  These are just some of the reasons why, we feel, a properly-prepared whey protein isolate is the only intelligent option for use in whey protein nutritional supplements.

Note: Not all whey protein isolates offer the full benefits of filtered whey isolates – whey isolates produced by the ion exchange method, for example, lack an important whey microfraction called glycomacropeptide.  Additionally, some whey concentrates may be produced so as to minimize the formation of denatured proteins – these whey concentrates, however, would still contain lactose, fat, and most importantly, cholesterol – which is prone to oxidation during the shelf life of the powder.

Q. What is oxidized cholesterol, and what are its health effects?

A. When a cholesterol molecule interacts with oxygen, oxidized cholesterol may be formed.  While unoxidized, or native cholesterol is an important substance needed for the building of cellular structure and hormone synthesis, oxidized cholesterol is metabolized differently, and may be a unique contributor to heart disease and other types of metabolic and hormonal disruption.

Oxidized cholesterol, for example, has been implicated in the development of atherogenesis – the thickening of the arterial wall due to the build-up of fatty material – in other words, the beginning of the clogged arteries of heart disease:

Study Link - Atherogenic effect of oxidized products of cholesterol.

Quote from the above study:

Cholesterol under certain in vitro and possibly in vivo conditions may be oxidized to oxysterols, which are suspected of being initiators of atherosclerotic plaques… Dietary oxysterols are absorbed in the gastrointestinal tract and are selectively transported by the athrogenic lipoproteins LDL and VLDL. The oxysterols cholestanetriol and 25-OH cholesterol have been shown to be atherogenic. Oxysterols are commonly found in dried egg products, powdered milk, cheeses and in a variety of high temperature dried animal products.

As the above study indicates, cholesterol can oxidize inside our body, but it can also oxidize in the foods we eat.  While fresh cholesterol-containing foods, cooked normally, contain relatively low levels of oxidized cholesterol, cholesterol-containing dried, powdered, and “shelf-stable” foods are apt to contain relatively high levels of oxidized cholesterol.  This includes foods such as powdered eggs, powdered milk, powdered cheese, and whey protein concentrate.

Studies have shown that the oxidized cholesterol in such foods is absorbed and is taken up by the cholesterol-carrying lipoproteins, leading researchers to note that dietary sources of oxidized cholesterol may be unique contributors to atherosclerosis:

Study Link - Oxidized cholesterol in the diet is a source of oxidized lipoproteins in human serum.

Quote from the above study:

It is possible that oxidized cholesterol in the diet accelerates atherosclerosis by increasing oxidized cholesterol levels in circulating LDL and chylomicron remnants.

Because the formation of cholesterol oxides is inevitable in any powdered product which contains cholesterol, we feel that all cholesterol-containing powders (and many products made from them, like ready-to-drink protein shakes) should be avoided by any health-conscious consumer.

Studies have found, for example, that the formation of cholesterol oxides in dairy powders steadily increases during the shelf life of the powders – even when the products are stored sealed at room temperature:

Study Link - Determination of Cholesterol Oxides in Dairy Products. Effect of Storage Conditions.

Cholesterol oxidation is likely to be an even greater problem with many ready-to-drink protein shakes which are made with whey protein concentrate powder – and which are then pasteurized at high temperatures, often in the presence of oxidizing agents like unsaturated fats and minerals such as copper and iron.

Ultimately, it’s clear that oxidized cholesterol is metabolized in a fundamentally different way relative to native cholesterol, and is likely to be significantly harmful as a result. 

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February 01, 2012

Whey Protein Q&A - Whey Protein And Weight Loss

BlogProQAC Q. Can whey protein help with weight loss?

A. Whey protein is likely to have particular benefits for people looking to lose weight.  Out of the three macronutrients (protein, carbohydrate, and fat), protein is known to suppress appetite the most.  And while this is true for pretty much any protein source, whey protein may assist weight loss for several additional reasons.

The authors of the scholarly article below note that calcium, branched-chain amino acids (which whey contains in abundance), and unique whey peptides are all likely to make whey protein a powerful tool for weight management:

Study link - Role of whey protein and whey components in weight management and energy metabolism.

Quote from the above study:

…the anti-obesity effect [of whey] appears to result from calcium, high proportion of branched chain amino acids, and specific bioactive whey-derived peptides.

Whey protein has also been shown to reduce appetite particularly well – and the whey microfraction called glycomacropeptide (GMP) may be an important factor in this effect.  Studies have found that consuming whey proteins which contained GMP at breakfast led to reduced caloric intake at subsequent meals, relative to consuming whey proteins without GMP:

Study Link - Effects of complete whey-protein breakfasts versus whey without GMP-breakfasts on energy intake and satiety.

Quote from the above study:

[Energy intake] at lunch was lower after whey than after whey without GMP…GMP as a whey–fraction reduced energy intake coinciding with increased concentrations of certain amino acids, irrespective of the concentration of whey–protein. Although between different concentrations of whey–protein differences in hormone responses were observed, these were unrelated to satiety ratings or energy intake.

A recent study published in the Journal of Nutrition found that the long-term consumption of whey protein was associated with lower body weight and lower body fat mass in overweight and obese adults.

The study subjects consumed 56 grams of either whey or soy protein daily, or an equal amount of calories as carbohydrates.  The participants otherwise consumed their normal diets.  After 23 weeks of supplementation, the fat mass of those consuming whey protein was 2.3 kilograms (just over 5 pounds) less than those consuming an equal amount of calories as carbohydrates. 

Study Link – Whey Protein but Not Soy Protein Supplementation Alters Body Weight and Composition in Free-Living Overweight and Obese Adults.

Quote from the above study:

In this study in which energy restriction was not part of the intervention, changes in body weight and composition were small but nevertheless suggest that habitual consumption of supplemental protein may result in improved body composition and incremental, but ultimately significant, weight loss. These data suggest that supplemental dietary protein may reduce the risk of unhealthy weight gain observed in many populations (i.e. 500–1000 g/y).

An interesting aspect of the above study was that the subjects consuming whey protein lost weight and fat mass without consciously restricting calories. 

Similar studies have found that whey protein may allow dieters to not only lose weight, but to maintain significant muscle mass while dieting – an important aspect of long-term dieting success:

Study Link - A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study.

In all, quality whey protein is likely to be an important part of any weight-management program.

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January 30, 2012

Whey Protein Q&A - Whey Protein's Unique Benefits

BlogProQAC In recent years, protein powders and protein-fortified drinks and food bars have become increasingly common staples of many people’s diets.  While a select few of these products may have nutritional benefits, many may actually do more harm than good.  In this series of Q & A articles, we’ll see how to choose protein supplements that are actually health-promoting (such as undenatured whey protein isolate).  We’ll also see exactly how to use such protein supplements to achieve maximal benefit for growth, repair, recovery, and optimal health.

Q. What is Whey?

A. Whey is the watery part of milk separated from curds during the making of cheese.  Sweet dairy whey, which is the raw precipitate from cheddar-type cheeses, contains quite a bit of lactose and fat – and relatively small amounts of protein.  Where whey was originally thought of as a mere waste product, the dairy industry often sold powdered whey for use as a cheap animal feed, but researchers eventually found that the protein portion of whey (if protected from denaturation/damage by careful extraction methods) had potentially remarkable health benefits for humans.

Q. What is Whey Protein?

A. The small amount of protein in whey is greatly concentrated when water, lipids, and lactose are removed – the resultant product is known as whey protein.  Different whey proteins may contain anywhere from 34% to over 90% protein by weight depending upon how they’re processed.

The term whey protein doesn’t just refer to one type of protein, but actually encompasses many different subtypes of protein collectively called microfrations.  Research has found that each of whey’s microfractions imparts unique and often powerfully health-promoting benefits.  Whey protein microfractions include:

Beta-Lactoglobulin

Alpha-Lactalbumin

Glycomacropeptide

Bovine Serum Albumin

Immunoglobulins

Lactoferrin

Not all whey protein products, however, contain the full array of whey’s microfractions.  Many of the most health-promoting microfractions are often damaged in the production of whey protein powders, and some whey protein production methods (e.g., the ion-exchange method) are unable to extract the full gamut of whey’s microfractions. Ultimately, only products which are produced using low temperatures and selective filters are capable of delivering the full array of undenatured and active whey proteins.

Q. How is whey protein different than the protein in foods such as eggs, chicken, or beef?

A. The protein found in eggs, chicken, and beef is generally high quality, but because of whey’s unique composition, properly-prepared whey protein is capable of offering benefits above and beyond other such protein-containing foods.  For starters, whey protein is the richest source of key muscle-building amino acids such as leucine – likely a major reason why whey protein is unsurpassed in supporting muscle growth and repair. 

But, whey protein’s benefits aren’t solely due to its amino acid composition.  Whey’s unique microfractions have functional benefits above and beyond being a source of the amino acids which make up the body’s tissues and enzymes.  These microfractions, for example, may support immune function and cellular detoxification.  Several whey microfractions have been shown to support the growth of healthy bacteria in the intestines (meaning that whey protein may support digestive health, appetite suppression and weight loss).  Certain whey peptides may support healthy blood pressure, and whey protein has also been shown to support the proper metabolism and storage of carbohydrates, thus supporting healthy blood sugar levels.

In all, whey protein is far more than just a “building block” for the body’s tissues – it may support both the structure and function of our body’s cells like no other protein available.

Q. Research shows that, for all its shortcomings, the standard American diet contains sufficient protein.  Even athletes can easily meet their elevated protein requirements with readily-available foods.  Why should people consider taking a whey protein supplement?

A. Properly-prepared, undenatured whey protein is likely to offer unique benefits above and beyond those of other protein sources.  While most sources of protein such as beef, chicken, and eggs simply supply amino acids for growth and repair of the body’s tissues, the unique peptides in undenatured whey protein impart numerous biological benefits involving immunity, antioxidant status, healthy blood sugar, bone health, blood pressure, and digestive health to name just a few.  Because of its far-reaching effects, whey protein is far more than just a means to add additional protein to the diet, and even those whose diet already contains sufficient protein can still benefit from adding undenatured whey protein.

For example, unique sulfur-containing peptides in whey may be able to enhance the production of the cellular antioxidant and detoxifier known as glutathione.  Glutathione plays an important role in the immune system and in the proper growth and repair of the body’s cells.  Numerous studies show that whey protein may be able to enhance glutathione levels in those with compromised immune systems (including athletes):

Study Link - Whole blood and mononuclear cell glutathione response to dietary whey protein supplementation in sedentary and trained male human subjects.

Quote from the above study:

The aerobic training period resulted in significantly lower glutathione concentrations in whole blood, an effect that was mitigated by WPI [Whey Protein Isolate] supplementation. A significant increase in mononuclear cell glutathione was also observed in subjects receiving the WPI supplement following the 40 km simulated cycling trial.

Study Link - Oral supplementation with whey proteins increases plasma glutathione levels of HIV-infected patients.

Quote from the above study:

In glutathione-deficient patients with advanced HIV-infection, short-term oral supplementation with whey proteins increases plasma glutathione levels.

Study Link - Improved glutathione status in young adult patients with cystic fibrosis supplemented with whey protein.

Studies have also found that, unlike casein protein (another protein in milk), whey protein may support healthy blood lipids, insulin, and blood pressure levels in overweight and obese individuals:

Study Link - Effects of whey protein isolate on body composition, lipids, insulin and glucose in overweight and obese individuals.

Quote from the above study:

The present study demonstrated that supplementation with whey proteins improves fasting lipids and insulin levels in overweight and obese individuals.

Study Link - The chronic effects of whey proteins on blood pressure, vascular function, and inflammatory markers in overweight individuals.

Quote from the above study:

This study demonstrated that supplementation with whey protein improves blood pressure and vascular function in overweight and obese individuals.

The whey microfraction, gycomacropeptide, may exert its wide-ranging biological effects via its ability to support healthy bacterial populations in the intestines.  Such an effect could lead not only to appetite reduction, but to benefits for digestive, and overall health.

In research published in the Journal of Nutrition, for example, researchers from the University of Granada School of Pharmacy found that Glycomacropeptide was able to reduce intestinal inflammation on par with anti-inflammatory drugs in a rat model of chemically-induced colitis:

Study Link - Bovine Glycomacropeptide Is Anti-Inflammatory in Rats with Hapten-Induced Colitis

Quote from the above study:

The magnitude of the anti-inflammatory effect was generally comparable to that of sulfasalazine, an established drug used in the treatment of inflammatory bowel disease.

Recently, researchers have found that whey protein may possess the unique ability to stimulate bone–building cells, called osteoblasts, while at the same time reducing bone resorption, or, the breaking down of bone:

Study Link – Effect of whey protein on the proliferation and differentiation of osteoblasts.

Quote from the above study:

This study establishes whey protein as a potent novel anabolic factor in osteoblasts, and which also reduces bone resorption.

And though the above study was conducted in vitro, animal and human studies have also shown various whey proteins to offer bone–building benefits above and beyond other types of protein. The following study, for example, found that rats fed small amounts of whey protein had higher levels of bone–specific proteins and stronger bones than those fed exclusively casein:

Study Link – Effects of whey protein on calcium and bone metabolism in ovariectomized rats.

Quote from the above study:

These data indicate that the milk whey protein influence in OVX rats is an increase in bone proteins such as collagen and enhanced bone–breaking energy.

Whey protein may also offer unique benefits for regulating blood sugar.  Because of the unique proteins it contains, whey protein in insulinogenic – meaning, that it facilitates the release of insulin and thus aids in the storage and utilization of carbohydrates.

Human studies have shown that mixtures of whey and casein protein combined with carbohydrates led to significantly greater rates of glycogen storage relative to either carbohydrate or protein alone:

Study Link - Carbohydrate-protein complex increases the rate of muscle glycogen storage after exercise.

Quote from the above study:

The rate of muscle glycogen storage during the CHO-PRO treatment [35.5 +/- 3.3 (SE) mumol.g protein-1.h-1] was significantly faster than during the CHO treatment (25.6 +/- 2.3 mumol.g protein-1.h-1), which was significantly faster than during the PRO treatment (7.6 +/- 1.4 mumol.g protein-1.h-1). The results suggest that postexercise muscle glycogen storage can be enhanced with a carbohydrate-protein supplement as a result of the interaction of carbohydrate and protein on insulin secretion.

Subsequent animal studies have found that whey protein (more so than casein) is uniquely responsible for increasing glycogen levels after exercise.  Such research gives us important clues as to how to use whey protein to maximize exercise recovery – a topic we’ll cover later in this Q&A.

Study Link - Dietary whey protein increases liver and skeletal muscle glycogen levels in exercise-trained rats.

Quote from the above study:

Total glycogen synthase activity in the skeletal muscle in the whey protein group was significantly higher than that in the casein group. The present study is the first to demonstrate that a diet based on whey protein may increase glycogen content in liver and skeletal muscle of exercise-trained rats.

An excess of iron is a common cause of the oxidative stress and free radical production found in aging and disease.  The iron-binding whey microfraction, called lactoferrin, has been associated with numerous health benefits, and It’s likely that lactoferrin may help our bodies use iron safely and efficiently:

Study Link - Milk whey protein decreases oxygen free radical production in a murine model of chronic iron-overload cardiomyopathy.

To be continued...

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April 27, 2011

Whey Protein Enhances Muscle and Liver Glycogen Storage – Implications For Muscle Growth and Exercise Recovery.

WorkoutCurl Even in academic circles, dietary protein is often simplistically viewed as a mere source of amino acid “building blocks” for the body’s tissues and enzymes.  Decades’ worth of research clearly shows, however, that certain food proteins and peptides exert remarkable biological effects independent of their role in forming the structural material of tissues and enzymes.

Dairy proteins – and whey proteins in particular – happen to be among the richest sources of such bioactive peptides.  In previous Integrated Supplements Blog articles, for example, we’ve examined how the potent antioxidant activity of whey’s cysteine-containing peptides may be of unique benefit in conditions characterized by oxidative stress such as diabetes:

Select Studies on Whey Protein - Whey Protein, Blood Sugar, and Oxidative Stress

We’ve seen how the iron-binding properties of whey’s lactoferrin peptide may protect against iron-induced oxidative damage:

Select Studies on Whey Protein - Whey Protein Protects Against The Toxic Effects Of Iron

And, we’ve seen how the whey peptide called glycomacropeptide may suppress appetite, ultimately leading to reduced caloric intake:

Study Finds Whey Protein Containing Glycomacropeptide Leads To Reduced Calorie Consumption

As it turns out, even the muscle-building properties of whey protein aren’t solely due to protein’s role as a structural component of muscle tissue.  Whey protein may have the unique ability to facilitate the uptake and storage of carbohydrate in the body’s cells – thus creating the optimal environment for exercise recovery and muscle growth.

Muscle and Liver Glycogen – Keys to Exercise Performance, Recovery, and Muscle Building

Glycogen is the storage form of carbohydrate found in the body’s cells.  When energy demands are taxed – as they are in intense exercise – levels of muscle glycogen and the “emergency reserve” of liver glycogen become drained.  In this scenario, not only does performance suffer (glycogen depletion is thought to be a major factor in the fatigue of endurance athletes, for example), but recovery from training is hindered as well.  This is why the muscle-building effects of weight training are often hindered by inadequate nutrition.  In other words, no matter how much protein is consumed, muscle protein synthesis (i.e., muscle growth) simply cannot occur optimally until glycogen stores are replenished.

In fact, monitoring the level of liver glycogen may be a fundamental way in which the body gauges a fed state (i.e., a metabolic environment suitable for growth and repair).  When liver glycogen is low, the body may elicit the adrenaline-driven “fight-or-flight” response which converts structural (e.g., muscle) proteins into fuel sources – obviously, not the ideal situation for muscle growth. 

Note – the role of liver glycogen as a signal of the fed state is outlined in our article:

A Diet For Long-Term Weight Control And Optimal Health - Part 2 - The True Role of Sugar in Weight Gain, Diabetes, and Metabolic Syndrome

Whey Protein Increases Glycogen Levels

Recent research has shown that whey protein may be unique among protein sources in facilitating the uptake and storage of muscle and liver glycogen.

Human studies have shown that mixtures of whey and casein protein combined with carbohydrates led to significantly greater rates of glycogen storage relative to either carbohydrate or protein alone:

Study Link - Carbohydrate-protein complex increases the rate of muscle glycogen storage after exercise.

Quote from the above study:

The rate of muscle glycogen storage during the CHO-PRO treatment [35.5 +/- 3.3 (SE) mumol.g protein-1.h-1] was significantly faster than during the CHO treatment (25.6 +/- 2.3 mumol.g protein-1.h-1), which was significantly faster than during the PRO treatment (7.6 +/- 1.4 mumol.g protein-1.h-1). The results suggest that postexercise muscle glycogen storage can be enhanced with a carbohydrate-protein supplement as a result of the interaction of carbohydrate and protein on insulin secretion.

Subsequent animal studies have found that whey protein (more so than casein) is uniquely responsible for increasing glycogen levels after exercise.

Study Link - Dietary whey protein increases liver and skeletal muscle glycogen levels in exercise-trained rats.

Quote from the above study:

Total glycogen synthase activity in the skeletal muscle in the whey protein group was significantly higher than that in the casein group. The present study is the first to demonstrate that a diet based on whey protein may increase glycogen content in liver and skeletal muscle of exercise-trained rats. 


In all, it seems that whey protein along with a source of carbohydrates (including some fructose) – consumed either before or after workouts – is the ideal way to maximize the muscle-building effects of exercise.

Ideally, the whey protein chosen will contain the full spectrum of whey’s bioactive peptides, be all-natural, and free of residual amounts of cholesterol – as is Integrated Supplements CFM® Whey Protein Isolate.

Related Articles:

Building The Perfect Workout Drink With Whey Protein Isolate

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