Amino acids are often described as one of the building blocks of human life. Amino acids are a group of 20 organic acids (containing carbon), each of which has nitrogen and hydrogen atoms in its construction.
Amino acids are most numerous chemicals in the body. Amino acids are present in the thousands of different proteins that are employed within the body to construct and maintain its muscles, skin, bone, and organs. Proteins are also required in the manufacture of hormones, the chemical-signaling agents secreted in the various glands that constitute the body's endocrine system, controlled by the thyroid gland. Proteins are also the key ingredient in the formation of collagen, the elastic tissue that permits the ligaments, tendons, and all connective tissues of the body their range of movement.
Of the 20 amino acids utilized in a variety of body functions and processes, nine acids are classed as essential amino acids. These chemicals are not capable of being produced or synthesized within the body, and each must be obtained through dietary sources. The remainder are classed as nonessential amino acids, substances that are manufactured within the body, chiefly through the action of the liver.
Amino acid supplements are a part of the broader range of protein supplements used by some athletes to obtain specific training advantages. Sports that place a premium on muscle mass and strength, such as weightlifting, wrestling, American football, and various track and field events such as the shotput, are those athletes often seek to gain the perceived benefits of additional amino acids to assist them in their strength training.
The theory in support of amino acid supplements is straightforward in its reasoning. A traditional balanced diet will be composed of 60-65% carbohydrates, 12-15% protein, and less than 30% fats, in addition to proper vitamins, minerals, and an ample supply of phytochemicals consumed as a part of the carbohydrate/protein/fat regime. Athletes endeavoring to build greater strength will often correspondingly increase the amount of protein; the desired amino acids will be extracted from these protein sources through the digestive and absorption process. Proteins are not created equal; not all protein sources contain the same amounts or quality of protein, as measured by the quality of the amino acids contained in the food. In the assessment of protein quality, the amino acid structure of an egg is the standard against which all proteins are measured. Athletes who use protein supplements will seek an increase in both the quantity of amino acids ingested, as well as a high quality protein to supply the best and most useful amino acids.
It is a cardinal rule of the twin sciences of diet and nutrition that all macronutrients (carbohydrates, proteins, and fats) and micronutrients (all vitamins and most minerals) are most efficiently absorbed into the body through food, as the body is constructed to best receive and absorb these substances through digestion. On that basis, a protein supplement is an inferior means by which to consume proteins.
The secondary issue concerning amino acid supplements is the linear assumption that if the athlete wishes to build more muscle, the athlete will require more protein to be metabolized into amino acid. The modern trend in sports science is directed away from significantly increased amino acid consumption. The formation of additional muscle tissues in response to training demands can be achieved through increases of amino acids consumption of less than 5%.
Excess amino acids are not stored within the body in the manner of fats (through adipose tissue) or carbohydrates (either through glycogen or through conversion to fats). The body tends to dispose of excess amino acids through the breakdown of the acid and disposal through the renal system. Protein breakdown creates urea, which precipitates stress on the renal system.
Amino acid supplements carry all of the other risks inherent in any form of dietary supplementation. Unless the product is obtained from a known and proven source (or the athlete has the means to test the product themselves, an unlikely proposition), supplementation carries with it an element of risk. The risks assumed are both legal and physiological.
The legal risks for an elite athlete in the use of amino acid supplements is the history, within the industry, of adding substances to the formulation that are either not disclosed to the consumer or are disguised in the packaging. Studies conducted in the United States after 2000 determined that up to 25% of the tested protein or amino acid supplements contained forms of anabolic steroids, or anabolic steroid prohormones (precursors)—chemicals that facilitate the production of testosterone in the body. Such substances are clearly added to supplements by manufacturers to promote greater strength and weight gains among its users, all of which would be attributed to the "legal" ingredients listed on the commercial packaging.
The consumption of hidden anabolic products may pose a significant health hazard to consumers. If an elite athlete were the subject of a doping test and failed the test on the basis of these unknown additives, the prevailing legal view of anti-doping agencies worldwide is that of strict liability on the part of the athletes: they will be generally held accountable for anything that they ingest into their bodies.