Amino Acid Supplementation

Amino acids are nutrients that combine together to create proteins. Proteins are one of the nutrients the body uses for energy. There are two categories of amino acids: essential and nonessential. The body requires you to ingest essential amino acids, through foods that have "complete" proteins. However, the body can produce its own nonessential amino acids. Many athletes use amino acid supplementation in an effort to increase athletic performance.


Athletes use amino acids, such as arginine and lysine, with the belief that they will increase the release of growth hormone in the body. Growth hormone plays a role in forming muscle. Endurance athletes often use other amino acids, such as leucine, in an effort to reduce fatigue during training.


  • Loose stool (diarrhea).

  • Stomach pain.

  • Headache.

  • Cough.

  • Constipation.

  • Fainting.

  • Fatigue.

  • Rash.

  • Seizures.

  • Hepatitis.

  • Joint pain.

  • Rash, joint pain, fatigue, and death (eosinophilia-myalgia syndrome).

  • Rapid heart rate (tachycardia).

  • Inflammation of the muscle (myositis).


Protein is an essential part of the diet. However, the amount needed in an athlete's diet is debated. Currently, the advised intake of protein for an athlete is 1.5 grams for each kilogram of body weight. There is little evidence to suggest that increased protein intake will improve athletic performance. There are currently some animal studies showing the benefits of amino acid supplementation. However, these results have not been reproduced in human studies.


The best way to prevent adverse effects of amino acid supplementation is to consume the advised amount of protein only through your diet. Supplements do not go through rigorous testing. They may contain impurities that could cause further side effects. It is not known how amino acid supplementation effects athletic performance.