The Importance of Protein - Examining the Best of the Best

Importance of Protein

Choose your Protein Supplements Wisely

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Creatine is fantastic. Glutamine is even better. Of all the supplements being touted, though, the most important, the supreme, the one in a class by itself, the must-have supplement for muscle repair and growth, is protein. Protein is the most important supplement for bodybuilders, period.

As a fitFLEX reader, you already know that protein rules. You're almost surely using a protein powder or high-protein meal-replacement powder (MRP) one to three times a day to keep your daily intake at a gram or more per pound of body-weight.

We don't need to bore you with all the scientific studies showing that increases in lean mass are closely associated with increases in protein intake. Judging from our conversations with bodybuilders at contests, seminars, fitness expos and gyms across the country, however, it's clear that many of you don't know what to think or who to believe when confronted by the many visually and technically sophisticated, but often misleading, claims for the different types of protein available.

Since most of you are not pursuing doctoral degrees in nutritional biochemistry, how do you distinguish which protein choice is the best? With so many types of protein out there, including soy, egg white, whole egg, casein, whey, meat, glandular and collagen, how do you determine which one is the best in terms of bodybuilding value? You can try them all, but who has the time and money for that?

Well, we do. We've analyzed the major protein supplement sources and looked at the different elements that make them work, including digestibility, solubility and mixability. A protein supplement can't work, no matter how much protein is in the brew, if it isn't getting into your system efficiently. Worse, if the protein or other ingredients upset your digestion or are absorbed too fast, it could actually hurt your potential for recovery and muscle growth. Let's first look at the forms of supplemental protein out there.


The primary source of protein for bodybuilding supplements is milk. Milk protein is almost always exclusively derived from cows and is commercially available as whole-milk protein, whey protein and casein.

Milk protein

Since milk protein is provided by nature to support humans in infancy - a period of the greatest growth requirements in one's lifetime - it is an ideal source for supplements. Milk protein is quite species-specific, though, meaning that cow's milk and human milk differ significantly. For instance, human milk contains roughly 10 times more lactoferrin (an antiviral/ antibacterial iron-binding protein) than cow's milk. Cow's milk, then, is not the ideal for human growth, but it's what we have (unless you're an infant, in which case you have access to mother's milk). Nonetheless, the results obtained by bodybuilders who use milk protein, as well as results obtained in a large number of studies performed over the last 50 years, have enhanced and solidified the reputation of milk protein in the fitness and medical industries.

Whey protein

Whey has been singled out as the ultimate form of protein for bodybuilders, based on its essential amino acid composition, branched-chain amino acid (BCAA) content, sulfur amino acid content (methionine and cysteine), taste, ease of mixing and stability in liquids. The fact that it is digested rapidly, especially when compared to casein, was once also considered a plus, although this is now being perceived as a potential drawback. The touted advantages of whey, fueled by a plethora of publicity in bodybuilding and fitness magazines, have made it the protein of choice for most bodybuilders.

Basically, whey is the liquid that remains after casein and fat have been removed from milk. Manufacturers separate casein (a coagulated milk protein) from whey using either of two processes that have a significant impact on the quality of the product. In the most general terms, one method uses acids and the other uses specialized filtration systems. The acids in the first method can denature (deteriorate) the valuable protein fractions in the whey.

When acid is used to separate casein from skim milk, for example, the whey derived will not contain the important nutrient glyco-macropeptide or much, if any, of the desirable acid-sensitive fractions. Another beneficial nutrient, alpha-lactalbumin - considered to be perhaps the most digestible and nutritive fraction - is partially denatured when exposed to acid, as are immunoglobulins and lactoferrin.

Why is acid used? Most whey is a byproduct of the manufacturing of cheese, which requires the use of organic acids (lactobacillus cultures). Unfortunately, the product label on a whey protein powder won't tell you which process was used to create the protein. That situation may change in the future as consumers become more educated and demand more complete information. Some manufacturers now add back in beneficial components that were once lost during processing, such as calcium and other minerals.

Ion-exchange whey was all the rage a few short years ago, but that bloom is now off the rose. It turns out that the ion-exchange process destroys some of the beneficial ingredients present in whey. Some components lost in the process have significant physiological and digestive properties, including lactoferrin, lactoperoxidase (an enzyme), and even a small amount of alpha-lactalbumin. On the other hand, Ion-X does provide extremely pure proteins.

Whey definitely possesses some interesting and possibly potent nutritional properties, but remember to be a bit skeptical when you hear it being hailed as the best form of protein. Producers of casein and cheese once considered whey a waste product and dumped it into waterways, until the Environmental Protection Agency began forcing them to dispose of it in more ecologically friendly ways.


In short, casein is cheese. Caseinate (the dried form) used for dietary supplements is generally produced by an acid process. The two ultimate types of casein are micellar (an aggregation of small spheres of protein molecules) and the kind that is found in "native" milk protein (which is about 80% casein and 20% whey). These two types are completely undenatured, and they contain minerals (calcium, magnesium, phosphorous, potassium) within their cluster of protein molecules. Because of this structure, calcium, which has the potential of reducing the absorption of some other minerals, is absorbed along with the digested protein fragments to which it's attached. Micellar casein is produced from cold processing and nanofiltration - with no acids or heat to denature the product.

A landmark study (Y. Boirie et al., "Slow and fast dietary proteins differently modulate postprandial protein accretion," Proceedings of the National Academy of Sciences USA, 94[26]:14930-5, 1997) demonstrated that, when compared to whey, casein exhibited greater anticatabolic effects and much steadier and more efficient delivery of amino acids to the bloodstream and muscles.

Micellar casein yields byproducts during digestion that slow the passage of materials through the digestive tract. Slower movement usually means better digestion and absorption. This can be especially important under conditions that tend to "excite" the gut and speed the passage of materials: periods of stress, including hard training; and consumption of substances like caffeine, ephedrine and large quantities of liquid protein.

Since the publication of the Boirie study, the trend is away from straight whey and toward combinations of whey and casein, sometimes with soy added. When whey is taken alone, a large portion of it is used for energy instead of muscle building. Combining micellar casein and whey gives you the best of both worlds. Whey has anabolic and other beneficial fractions, but its speed through the digestive process may prevent absorption and optimal utilization. Casein slows the movement through the gut, and provides anticatabolic properties not present in whey. The ideal proportions of whey and casein haven't yet been determined. However, we know that the milk of animals with greater bone and muscle mass contains higher percentages of casein (cow's milk, for example, contains a higher percentage of casein than human milk). So, a bodybuilder probably needs more than just a smidgen of casein to derive maximal benefits from combinations of whey and casein.


Once left for dead, soy protein has been resurrected, thanks to new processes that have made it both more palatable and digestible. Today, soy proteins vary in taste and mixability. Most of the objectionable effects and qualities - gastrointestinal disturbances, gas, poor taste and mixability - associated with the relatively low purity of soy proteins have been eliminated.

Soy protein possesses some unique characteristics that distinguish it from animal-derived proteins; it appears to offer possible benefits for individuals who train. Soy, for example, is the only significant dietary source of two par-ticular isoflavones: genistein and diadzein. Research suggests that these isoflavones are partly responsible for soy's antioxidant actions, thyroid/metabolism-stimulating properties, cancer prevention, reduction of cardiovascular disease risk factors, maintenance of bone mass and amelioration of female gynecological complaints.

Those things are definitely impressive, but do they benefit muscle builders? Soy is healthful, and health is the ultimate foundation for building mass and strength. The FDA has recently allowed processors to make the claim that soy has the potential to reduce cholesterol and cardiovascular health risk factors (at an intake of just 25 grams per day). Also, some studies have shown that soy has positive effects on a variety of anabolic hormone levels in animals.

What's more, these isoflavones are considered phytoestrogens because their chemical structure resembles estrogenic steroids. Since they're weak estrogens, isoflavones may act as antiestrogens by competing with the much more potent naturally occurring estrogens for the body's estrogen receptor sites. This pre-vents estrogen from building up in your system.

Recent data have confirmed that soy protein is complete for humans on the basis of the PDCAAS (protein digestibility-corrected amino acid score, the new government-mandated method for rating protein). This fact is often overlooked by nutritionists and bodybuilders who rely on animal studies of protein utilization and on the promotional activities of some protein suppliers. Soy protein is 35% "critical cluster" amino acids, including glutamine, lysine and BCAAs; this is a higher percentage than in other proteins (whey, casein, egg, beef). And you probably already know how important amino acids are.

Like milk protein, soy protein quality is also dependent on the processing method. Some use ethanol/water mixtures that remove the beneficial isoflavones. The ethanol (alcohol) is the culprit in those methods - it denatures the soy protein.

Perhaps the ultimate test - other than in bodybuilders themselves - has been the seemingly successful use of soy protein for many years in infant formulas. Further, a number of recent supplementation trials of athletes (including gymnasts, swimmers, and badminton and baseball players) using soy protein have shown improvements in body composition, training and/or recovery. Word also comes to us that several college football teams have been using soy protein with gratifying results. The fact that soy costs less than egg, whey and some milk proteins has also improved the attractiveness of soy protein supplements.

Based on the favorable reports we're hearing about soy, we strongly recommend you try it (add 25-30 grams of soy a day as part of your total protein intake). We predict that you will see much more about it in the future.


The egg (the whole egg, not just the white) has been used as a reference protein against which other proteins are measured; that fact led to the perception that egg protein powders were the premier supplement. However, there are fewer egg protein products available because they are more expensive than other pure proteins, especially since the appearance of pure grades of whey protein. Egg proteins are frequently added to protein powders, usually in small amounts (less than five percent of a product's total protein), to gain consumer confidence and acceptance without significantly increasing cost. Although demand for egg protein is on the decline, there is definitely a place for it in a bodybuilder's diet (look for more on this in a future article). LAST AND MAYBE LEAST Protein supplements derived from rice, peas, beets, wheat gluten and other grains have appeared on the market. Their high cost and lack of perceived advantages over milk, egg or soy proteins severely limit their importance as protein supplements.

Vegetable protein sources are usually mixed with amino acids or protein hydrolysates (predigested proteins) to improve their biological value, which further increases expense. Likewise, fish proteins, bovine blood proteins, feather/hair (keratin) proteins and muscle proteins have appeared as protein supplements, but such unusual animal protein sources have also been unsuccessful with consumers. The only current exception is a collagen hydrolysate (see page 92), for use in protecting and treating joint and connective-tissue injuries.


Protein mixes are getting more sophisticated every day. Manufacturing techniques including blending proteins, predigestion and fortification with amino acids are being used to produce or enhance various proteins. Let's take a look at these extra features.

Time-released proteins Delivering a prolonged and steady stream of protein to the blood and muscles is the ultimate goal of bodybuilding nutrition. That's why we eat all those meals every day, and why eating frequently is probably the single most important nutritional commandment for serious bodybuilders. The bodybuilding effects should be greatest when the highest quality casein (micellar casein or native milk protein) is used. Unfortunately, for now, there is no way to determine the quality of the casein (or whey) from a product label.

When should you use a time-released product? One common trend in the industry is to advocate a large amount of protein per serving (up to 60 grams at one time). In liquid form, that could move through your gut quickly - possibly too quickly for optimal bodybuilding effects. We feel certain that a time-released protein product would be much more effective whenever you consume 40 grams or more at a time. Time-released products should be great to take at any time - day or night, with meals or in between.

Predigested proteins When you're serious about getting SAS (strong as s-t) and BAF (big as f-k), and downing 150-200 grams of solid food protein per day and another 100 from protein drinks or MRPs, your gut is working as hard as the rest of your muscles. You may actually deplete your protein-digesting enzyme levels. Intense exercise itself may even cause some gut debilitation via different forms of physiological fatigue.

Say you want more protein in order to get over this little plateau that's bugging you, but you don't want to stress your gut any more. You need something easier to digest. Your next snack should have a high di- and tripeptide content (two and three amino acids linked together), around 30-40%. Less might not be effective; much more may taste too bad to drink consistently. Human and animal studies alike show that these peptides are important because, when taken in significant amounts, they increase nitrogen retention.

High levels of di- and tripeptides in a protein (as opposed to minuscule levels of 5-10% of total protein, for example) deliver a much more favorable and even amount of amino acids to the bloodstream. They also do it quicker and with less being used for energy as com-pared to equal amounts of either whole proteins or free amino acids. In addition, they can increase serum albumin, which acts as a storehouse for aminos and is critical in maintaining water content in the blood. Any time is right for taking these predigested proteins, especially if you're already hitting high daily protein intake. They'd be especially beneficial after your workout.

A number of dietary supplements claiming to contain (predigested) protein hydrolysates (especially whey-protein hydrolysates) have been marketed, but from the chemical analyses we've performed, the amounts of di- and tripeptides found in them have ranged from none to too low to produce the same effects shown in the clinical studies. Again, until manufacturers publish and guarantee their products' chemical analysis, there's no way of knowing the quality of what you're buying.

Hydrolyzed collagen These nutri-ents may be a boon to those with connective-tissue problems or looking for a more complete recovery from exercise. Hydrolyzed (predigested) collagen is being studied in Europe as a treatment for knee-joint deterioration and osteoarthri-tis. Clinical trials have all shown slow but significant amelioration of symptoms, allowing patients to reduce pain-medication dosages after four weeks of administration of seven to 10 grams per day of hydrolyzed collagen.

Furthermore, administration of 10 grams of hydrolyzed collagen to athletes resulted in higher concentrations of plasma amino acids, which, in theory, may facilitate recovery from strenuous exercise.

For specific uses (such as joint injuries), hydrolyzed collagen with hydroxyproline-containing peptides (a form of the amino acid proline, which occurs in connective tissue) represents a uniquely valuable form of protein supplementation. Peptides and amino acids Two things have led to the development of a glutamine-rich protein hydrolysate: first, the recent surge in popularity of glutamine as an ergogenic aid for growth and recovery and, second, the knowledge that protein hydrolysates may enhance absorption of amino acids better than an equivalent amount of whole proteins or free-form amino acids. Glutamine peptide is stable - in stomach acid, for example - and easily digested and absorbed.

In order to get enough glutamine, you'll probably want supplements that are glutamine-enriched. Look for glutamine peptide or L-glutamine on the ingredients list, not glutamic acid or "glutamine precursors," as these are not the same thing as glutamine. L-glutamine is over 95% glutamine, whereas glutamine peptide contains only 30% glutamine. Therefore, if a label specifies 10 grams of glutamine peptide, it actually contains only three grams of usable glutamine (not 10 grams).

You may want to add some L-glutamine to your protein drink yourself. Remember that glutamine is sensitive to acid, so don't take it with meals, or it will be degraded by the acids that are degrading your food. Glutamine not only exerts systemic anabolic and anticatabolic actions, it increases the muscle-building value of all the rest of the protein you eat. Don't skimp on it. The recommended dose is 20 grams of glutamine per day. Take four to five grams with water or juice several times a day - first thing in the morning, just before bed, and especially right after your workout.

Other amino acids most commonly used to fortify protein supplements include BCAAs, taurine, methionine, arginine and ornithine. Although the scientific community has begun accumulating data on the effects of glutamine and BCAA supplementation in people who exercise, the effects of their use in protein supplements is not yet known. Likewise, the effects of other amino acids added to supplements are as yet also unknown. The doses of added amino acids in protein supplements often do not reach the efficiency levels used in human clinical studies.


In choosing a protein, watch out for products that contain gums. Gums thicken the drink and make it easier to flavor, but almost all the gums being used can interfere with the absorption of minerals and amino acids.

While quality is important, digestibility is key, especially at high intake levels. Your ability to digest and absorb protein depends on many factors - genetics, lifestyle, stress levels, training levels, other substances you consume, what you eat and drink, and more.

We don't know enough about protein utilization in athletes who consume huge quantities of these supplements to make truly definitive statements. So far, there have not been any head-to-head comparisons in exercising individuals of the effects of different proteins on nitrogen balance, muscle mass or strength. Most research involving humans seems to suggest that using a wide array of proteins elicits different physiological effects and is probably most effective for improving muscle protein synthesis and overall health. Your best bet may be to give all the different types a reasonable try and work out the combinations that produce great results. The optimal "formula" for daily intake may be a variety of proteins (including whey, casein and soy), plus extra glutamine.

If you can afford it, give the higher-priced products a try, as they may offer some potentially significant advantages. But by no means should you give up on the lower-priced products, provided they're from a reputable manufacturer. The protein that tastes best, mixes well and agrees with you is the one you're going to use in the quantity that will help you make the most of your potential.

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