Protein supplements have gained favor with athletes as a means of increasing their body's ability to develop and maintain skeletal muscle. Protein is one of the three essential components of the human diet, along with carbohydrates and fats. Protein, which is composed of various types of amino acids, provides the raw material for both muscle construction and repair, as well as playing an important role in the immune system, the endocrine (hormone production) system, and the transmission of nerve impulses throughout the nervous system. A supplement is any addition to an athlete's regular diet to achieve a particular nutritional goal; a supplement may be a natural or a synthetic product. Supplements are available in fluid, powder, and solid food formulations.
The issue of whether an athlete requires protein supplements is hotly debated in the sports nutrition industry. Many nutritional experts contend that the best way to ingest protein is by way of a properly constituted, well-balanced natural food diet. This position is supported by the fact that the body is well suited to receive proteins through natural digestive processes, and that supplementation is never as strong a dietary option as whole food sources of any nutrient, including protein. Whole foods will often contain phytochemicals, the components of food that do not possess any caloric or other nutritional value, but that act as important trace substances to promote healthy functions within the body, such as anti-oxidization and the bolstering of the immune system.
Protein supplements were first popularized by bodybuilders, weightlifters, and strength athletes. One appeal of the supplement was the fact that the quality of the proteins contained could be consistently high; the second appeal was the ability of the supplement to shore up any protein deficiencies that might arise after a particularly demanding workout or if the athlete was not able to consume requisite amounts of dietary protein at a given time. The third appeal of the supplement is that an athlete may be limited by lifestyle pressure, such as school, employment, or family, in the preparation of protein-rich foods in the best possible fashion. Supplements offer a quick and nutritionally effective alternative; some protein supplements are marketed as meal replacements, a nutritional concept that is a further extension of protein supplements.
The pro-supplement constituency also advances the argument that high quality, concentrated protein products will repair the muscles stressed from a demanding workout more quickly than proteins consumed through food. Among the proteins that are popular for this reason are whey protein (a byproduct of cheese), and soy protein, extracted from the soya bean. Glutamine, a specific type of amino acid, is another well-regarded component in many protein supplements.
There is no question that from a biological perspective, if the body has a shortage of protein, a supplement will assist in the correction of the deficiency. Protein deficiency will prohibit the body from affecting the repairs necessary to maintain muscles structure. The consumption of additional amounts of protein, over and above the amount necessary to promote healthy muscle development, must be approached with caution.
Many approaches to protein supplementation have been advocated on the premise that if a little extra protein is beneficial to muscle repair and growth, greater amounts of protein supplements must be even better. The error in this premise is revealed by the chemistry of how the body processes excess amounts of protein. Unlike carbohydrates, which have a particular series of storage mechanisms, such as muscle glycogen and liver glycogen, or the fats ingested in the body, which are stored in the adipose tissues designed for fat storage, excess proteins are broken down into their amino acid components for elimination. The deconstruction of amino acids produces several byproducts, particularly urea which must be subjected to further processing in the liver before it can be excreted through urine. The process of filtering additional amounts of urea from the body creates the potential to place a significant strain on renal (kidney) function.
There are particular times when the body is better equipped to digest and utilize nutrients of all types. Proteins are best provided to the athlete's body nearer a competitive or training event that resulted in muscle stress. As a general rule, the ingestion of a protein supplement is likely to be more effective if consumed 30 to 60 minutes after the event, rather than at a later time. Protein supplements will always serve to address a deficiency, but optimal absorption through the digestive processes of the small intestine occurs in a timeframe closer to the activity.
In sports such as the triathlon, where the athlete requires significant carbohydrate recovery at the end of competition, as well as the need for muscle repair and recovery, competitors will often consume a carbohydrate/protein mix of supplements to achieve this dual purpose. The effect of the supplement, taken immediately or within 30 minutes of the end of the event, is to "jump start" the bodily process of restoration.
There are further issues regarding the use of protein supplements and the precise method by which the supplement is consumed. The human digestive tract is constructed to most efficiently process foods into useable substances when the particular material reaches the digestive system in a food-like condition. The consumption of amino acid pills and similar formulations, a product that essentially bypasses the digestive process, as amino acids are a product of protein digestion, do not speed the absorption of these substances into the system.
see also Diet; Muscle protein synthesis; Nutrition and athletic performance; Protein ingestion and recovery from exercise.