For as long as people have been participating in athletic events they have been seeking competitive advantages over their opponents.  While these advantages have often been sought through hard training, superior conditioning, and various motivational techniques, they have also been sought through the consumption of substances believed to enhance performance.  According to McArdle, Katch, and Katch, “Ancient athletes of Greece reportedly used hallucinogenic mushrooms, plant seeds and ground dog testicles for ergogenic purposes, while Roman gladiators ingested the equivalent of ‘speed’ to enhance performance…. [In addition] athletes of the Victorian era routinely used caffeine, alcohol, nitroglycerin, heroine, cocaine, and the rat poison strychnine for a competitive edge.” (Sports and Exercise Nutrition, p. 318)

Today, athletes and non-athletes alike continue to consume an enormous variety of odd concoctions derived from plants, vitamins, minerals, and hormones—all believed to improve physical appearance and provide the upper hand in sporting events.  Many of these substances, however, have shown to be ineffective, unproven, or dangerous, regardless of whether they are consumed in regular or supraphysiological doses.  In addition, some of these ergogenic aids are either illegal, banned by sports organizations, or both due to the unfair advantages and potential health risks they create.  To complicate matters even further, the FDA’s ability to control vitamin, mineral, enzyme, hormone, botanical, amino acid, and herb supplements was reduced in 1994 when Congress passed the Dietary Supplement Health and Education Act.   According to this act (also known as DSHEA) the FDA “requires proof of purity, safety, and effectiveness for public consumption of over-the-counter and prescription pharmaceuticals.”  (Sports and Exercise Nutrition, p. 261)  Unfortunately, dietary supplements are considered food rather than pharmaceuticals, and are therefor not regulated by the FDA.  Consequently, the FDA has no control over the quality, content, effectiveness, or safety of ergogenic aids.

Due to the lack of government regulation and the myriad of potential health risks posed by the consumption of ergogenic aids, one may wonder if supplementation is safe, effective, or worth pursing.  To date, there is little scientific proof that the majority of dietary supplements contribute any benefit to the user.  There is, however, a solid body of scientific evidence to support the beneficial effects of a well-rounded and nutritious diet.  Of the three macronutrients, protein has received the most attention throughout history due to its anabolic effect on various tissues throughout the body.  Supposedly, the ancient Greek wrestler Milo of Crotona resistance trained with a calf for several months before killing and eating it in order to build more muscle mass for competition.  Today, athletes and general health seekers continue to gorge on protein in hopes of gaining more size and strength. Unfortunately, many people fail to understand that overconsumption of protein results in added fat rather than muscular hypertrophy.

Wilmore, Costill, and Kenney call proteins “a class of nitrogen-containing compounds formed by amino acids.”  (Physiology of Sport and Exercise, p. 334)  When the 8 essential and 12 nonessential amino acids are linked by peptide bonds in chains of more than 100 amino acids, a protein is formed.  When proteins are ingested, they are catabolized back into their constituent amino acids and then reassembled to serve a variety of functions including the growth, maintenance, and repair of muscle tissue. Wilmore, Costill, and Kenney recommend 1.6 to 1.7 g of protein per kilogram of body weight for those seeking muscular hypertrophy, and 1.2 to 1.4 g of protein per kilogram of body weight for those involved in endurance training.  But what happens when the total caloric intake of protein—in addition to fat and carbohydrates—becomes so high that the amount of food necessary to reach the required value is no longer practical?  It is for this reason that many people elect to utilize protein supplements, generally in the form of powders to be mixed with either milk or water.  The most common protein supplements in use are bovine colostrum, egg protein, soy protein, whey protein, and casein protein.  Of these, the last two have proven to be the most popular and effective—primarily because of their digestion rates.  Other reasons for whey and casien’s popularity include the banning of bovine colostrum by the NCAA (due primarily to its high insulin-like growth factor content), the cost of egg protein, and the lack of soy protein’s effectiveness for building muscle mass.

Whey protein is a component derived from milk to make various dairy products; it is a high quality protein source that digests quickly and allows for fast uptake of amino acids by the small intestine.  According to Dr. Jose Antonio, “whey protein is absorbed very quickly and produces peak levels of amino acids at approximately 60 to 90 minutes after ingestion and then returning to baseline levels at approximately three to four hours post-ingestion.” (Sports Nutrition and Supplementation Muscle Building Strategies, p. 21) In addition, Dr. Susan Kleiner states whey protein “is high in B-Complex vitamins, selenium, and calcium, [and also]…appears to boost levels of the anitoxidant glutathione in the body.” (Power Eating, p. 177) Finally, whey protein also contains high amounts of branched-chain amino acids—particularly leucine—which contributes to its effectiveness as both a pre and post workout supplement.  As previously stated, whey is consumed in a powder form mixed with either water or milk and usually contains approximately 25 to 30 grams of protein per serving.  To date, there is no research to indicate any adverse renal effects from consuming whey protein as a supplement to a well-rounded diet within the appropriate caloric level.

Casein is a component derived from skim milk in the form of sodium caseinate, potassium caseinate, and calcium caseinate; it comprises approximately 80% of the protein contained in milk, while the other 20% consists of whey.  Like whey, casein is a high quality protein.  But unlike whey, casein digests more slowly and allows for prolonged absorption by the small intestine.  Dr. Jose Antonio states “casein…produced a much slower and less dramatic rise in amino acid levels peaking at approximately 60 to 90 minutes but maintaining higher levels of amino acids over the entire seven hour time frame.” (p. 21)

It has been theorized that the different absorption rates of whey and casein protein have a direct effect on how they are metabolized by the human body.  Though neither protein is absorbed by the small intestine as quickly as a carbohydrate, the difference between the body’s utilization of whey and casein is similar to the difference between its utilization of a high and low glycemic carbohydrate.  Like a high glycemic carbohydrate, whey protein is rapidly taken up by the microvilli of the small intestine.  Casein, on the other hand, is similar to a low glycemic carbohydrate in that it is used at a far slower rate by the microvilli throughout a much greater length of the small intestine.  According to Dr. Antonio, “Whole body protein breakdown [is] inhibited 34% by casein ingestion but not whey.  Whey protein ingestion [stimulates] protein synthesis by 68% while casein [stimulates] protein synthesis to a lesser extent.” (p. 21) But as Dr. Antonio points out later, there are also studies that show little or no difference between the effects of whey and casein on muscular hypertrophy.  One study in particular yielded similar results for protein synthesis after the consumption of both whey and casein (separately and by different groups) following an acute bout of resistance training.  On the whole, however, “research suggest[s] that casein protein may provide more benefit than whey protein…one could speculate that if you were to consume a single protein source for gaining muscle mass, casein may be preferable over whey.” (Antonio, p. 21)

Ultimately, what does all this information mean for the individual seeking supplementation that will aid in his or her quest to build lean mass?  How can it be applied? Clearly, the rate at which the body uses whey and casein can provide distinct advantages when timed in conjunction with one’s workout and daily food intake.  Because of whey protein’s rapid absorption, it makes an ideal recovery food after a hard workout—particularly one involving the use of free weights within a program designed to illicit increases in and strength and size.  It can also make an excellent pre-workout snack that can be easily consumed 15 to 30 minutes before exercising.  Casein, on the other hand, could be consumed 60 to 90 minutes before exercising due to its slower absorption rate and ability to maintain high levels of amino acids for multiple hours.  In addition, if casein is taken before going to bed, it could also prove useful in blunting hunger and promoting muscle tissue repair while sleeping.

In short, there are highly practical applications for both whey and casein.  Through proper timing of nutrient intake and careful attention to correct dosage, athletes and general health-seekers alike can benefit—both safely and legally—from potential increases in muscle mass due to the use of these proteins.



  1. Antonio J., (2006). Sports Nutrition and Supplementation Muscle Building Stratgies.  NSCA’s Performance Training Journal, 21-23.
  2. Costill D.L., (2008). Body Composition and Nutrition for Sport.  Physiology of Sport and Exercise, 334-335.
  3. Katch F.I., Katch V.L., McArdle W.D., (2009). Making Wise Choices in the Nutrition Marketplace.  Sports and Exercise Nutrition,
  4. Katch F.I., Katch V.L., McArdle W.D., (2009). Pharmacologic and Chemical Ergogenic Aids Evaluated.  Sports and Exercise Nutrition,
  5. Kleiner S., (2007). Muscle Building Products.  Power Eating, 177-178.
  6. Kleiner S., (2006). Food and Muscle Gain.  The Powerfood Nutrition Plan, 154-158.

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