According to a 1993 U.S. study, amino acid formulas are the largest category of supplements marketed to bodybuilders.
Researchers concluded that this was probably due to the amazing claims made by the manufacturers -- increased muscle mass, increased strength and power, reduced body fat, and increased energy.
In addition, the desire of body builders to find a safe and effective alternative to illegal anabolic steroids to give them that "edge" in competition also increased sales.
However, what they and other reputable researchers have also concluded is that, currently, there is no scientific justification for these claims.
Types of amino acids.
Amino acids are the building blocks of protein. They are divided into "essential" amino acids - those that cannot be produced by the body and are supplied by food - and "non-essential" amino acids which are just as important and can also be found in food, but can be produced by the body.
Amino acid supplements.
There are about 25 amino acids sold singly or in combination as supplements. While unfamiliar to the ordinary person, words like ornithine, arginine, leucine, tyrosine etc. are common terms for a typical body builder. Most of the amino acid supplement formulas sold contain either "branched-chain amino acids" or "non-essential free amino acids".
Fatigue prevention claim.
Branched-chain (so-called because of their branched molecular structure) amino acids play a small role in providing energy during exercise. Manufacturers claim that supplementation with these type of amino acids will prevent fatigue during exercise.
Dr. Peter Lemon of Kent State University in Ohio says that the theories behind the use of these substances are interesting, but unproven. He claims that most of the studies done have been short-term studies and that longer-term studies are needed before it can be assumed that branched-chain amino acid needs are higher as a result of exercise.
Another claim made for the use of branched-chain amino acids is the "central fatigue hypothesis" in which supplementation with these amino acids is supposed to ward off fatigue during exercise by minimizing the brain serotonin (a neurotransmitter chemical) levels. Again, most scientists claim that this theory is compelling but still unproven.
Dr. William Evans of the Human Nutrition Research Center at Tufts University feels that there are numerous potential causes of fatigue that need to be ruled out before the supplementation of branched-chain amino acids can be pointed to as the solution. Nutritionists note that any branched-chain amino acids used as fuel during intense exercise can be easily replaced by consuming foods high in protein.
Growth hormone release claim.
Ornithine, lysine, and arginine, sold separately or in combination have attracted the attention of bodybuilders because manufacturers claim that they activate the secretion of growth hormone. This naturally occurring protein hormone stimulates muscle growth and decreases fat storage.
The two most common studies used to back up manufacturers' claims are the 1988 study by Dr. Elam and the 1990 research by Dr. Luke Bucci. However, what the manufacturers do not say is that more recent studies have shown no effect of oral arginine, ornithine or lysine supplementation on body composition or strength. An injection of arginine does stimulate growth hormone release; however, it makes no difference because the presence of growth hormone doesn't automatically mean larger muscles.
Dr. Kevin Yarasheski, Research Professor at Washington University gave either growth hormone or a placebo to two groups of weight lifters in a 1992 study, and observed no increase in muscle growth or muscle strength in the growth hormone recipients.
It appears that human growth hormone is only effective if an individual is deficient in the substance to begin with.
There are other amino acids, such as glutamine, that are also becoming popular among body builders. Glutamine is sometimes used to build up atrophied muscles that can occur after major surgery but additional studies still need to be done before it can be proven that glutamine supplementation works for anyone else other than individuals who have been bedridden for a long time.
Faster absorption claim.
Another claim that manufacturers make about amino acid supplements is that they are absorbed faster and, therefore, replenish the body's "protein pool" of amino acids sooner than whole protein. Researchers say even if free amino acids were absorbed faster, there is no evidence that this would, in turn, build new muscle protein.
Dangers of amino acid supplements.
According to Liz Applegate Ph.D., Nutrition Director of the Adult Fitness and Cardiac Rehabilitation Program of the University of California, individual amino acid supplements taken in excessive amounts (5 to 20 grams) may affect mood state by altering brain neurotransmitter levels. Animal studies have shown that high doses of certain amino acids may impair the immune system or may cause temporary blindness.
This may or may not be true for humans; no one can say because of the ethical problems of administering the same high doses to experiment participants.
Since the long-term safety of taking large doses of amino acids has not been established, the greatest fear that scientists have is that the amino acids might interact with other substances in the body in ways that are yet unimagined.
They caution that the ill effects of nicotine were not fully recognized for more than fifty years.
Go to archive...