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Branched-Chain Amino Acids for Sports & Fitness

Also known as: BCAAs, Isoleucine, Leucine, Valine

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What is it?

The branched-chain amino acids (BCAAs) are leucine, isoleucine, and valine. BCAAs are considered essential amino acids because human beings cannot survive unless these amino acids are present in the diet.

Where are they found?

Dairy products and red meat contain the greatest amounts of BCAAs, although they are present in all protein-containing foods. Whey protein and egg protein supplements are other sources of BCAAs. BCAA supplements provide the amino acids leucine, isoleucine, and valine.

Why do athletes use it?*

Some athletes say that branched-chain amino acids

  • helps improve strength training results.
  • helps improve endurance.

What do the advocates say?*

A good deal of research has been done on branched-chain amino acids (BCAAs) in athletes, but results are quite mixed. BCAAs do not seem to enhance training benefits or exercise performance in most situations. Some athletes, however, may experience increased mental clarity during exercise or may be less susceptible to infections caused by the stress of exercise. Performance under extreme conditions, such as high altitude or heat, may also be improved with BCAAs.

How much is usually taken by athletes?

Some research has shown that supplemental BCAAs (typically 10 to 20 grams per day) do not result in meaningful changes in body composition,1 nor do they improve exercise performance or enhance the effects of physical training.2 3 4 5 6 7 However, BCAA supplementation may be useful in special situations, such as preventing muscle loss at high altitudes and prolonging endurance performance in the heat.8 9 One controlled study gave triathletes 6 grams per day of BCAA for one month before a competition, then 3 grams per day from the day of competition until a week following. Compared with a placebo, BCAAs restored depleted glutamine stores and immune factors that occur in elite athletes, and led to a reported one-third fewer symptoms of infection during the period of supplementation.10 Studies by one group of researchers suggest that BCAA supplementation may also improve exercise-induced declines in some aspects of mental functioning.11 12 13

Are there any side effects or interactions?

Side effects have not been reported with the use of BCAAs. Until more research is conducted, people with ALS should avoid taking supplemental BCAAs. In one study, supplementation with a large amount of BCAAs (60 grams) caused alterations in the blood levels of tryptophan, phenylalanine, and tyrosine.14 The changes in the blood levels of these amino acids could, in theory, cause depression in susceptible individuals. Until more is known, individuals with a history of depression should consult a doctor before supplementing with BCAAs. People with kidney or liver disease should not consume high amounts of amino acids without consulting their doctor.

At the time of writing, there were no well-known drug interactions with branched-chain amino acids.

Resources

See a list of books, periodicals, and other resources for this and related topics.

*Athletes and fitness advocates may claim benefits for branched-chain amino acids based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on branched-chain amino acids. For more complete and detailed information, including references and safety information, see Branched-Chain Amino Acids as nutritional supplements.

References

1. Kelly GS. Sports nutrition: A review of selected nutritional supplements for bodybuilders and strength athletes. Alt Med Rev 1997;2:184–201.

2. Van Hall G, Raaymakers JSH, Saris WHM, Wagenmakers AJM. Supplementation with branched-chain amino acids (BCAA) and tryptophan has no effect on performance during prolonged exercise. Clin Sci 1994;87:52 [abstract #75].

3. Blomstrand E, Hassmen P, Ek S, et al. Influence of ingesting a solution of branched-chain amino acids on perceived exertion during exercise. Acta Physiol Scand 1997;159:41–9.

4. Madsen K, MacLean DA, Kiens B, et al. Effects of glucose, glucose plus branched-chain amino acids, or placebo on bike performance over 100 km. J Appl Physiol 1996;81:2644–50.

5. Davis JM, Welsh RS, De Volve KL, et al. Effects of branched-chain amino acids and carbohydrate on fatigue during intermittent, high Intensity running. Int J Sports Med 1999;20:309–14.

6. Vukovich MD, Sharp RL, Kesl LD, et al. Effects of a low-dose amino acid supplement on adaptations to cycling training in untrained individuals. Int J Sport Nutr 1997;7:298–309.

7. Freyssenet D, Berthon P, Denis C, et al. Effect of a 6-week endurance training programme and branched-chain amino acid supplementation on histomorphometric characteristics of aged human muscle. Arch Physiol Biochem 1996;104:157–62.

8. Schena F, Guerrini F, Tregnaghi P, et al. Branched-chain amino acid supplementation during trekking at high altitude. The effects on loss of body mass, body composition, and muscle power. Eur J Appl Physiol 1992;65:394–8.

9. Mittleman KD, Ricci MR, Bailey SP. Branched-chain amino acids prolong exercise during heat stress in men and women. Med Sci Sports Exerc 1998;30:83–91.

10. Bassit RA, Sawada LA, Bacurau RF, et al. The effect of BCAA supplementation upon the immune response of triathletes. Med Sci Sports Exerc 2000;32:1214–9.

11. Hassmén P, Blomstrand E, Ekblom B, Newsholme EA. Branched-chain amino acid supplementation during 30-km competitive run: mood and cognitive performance. Nutrition 1994;10:405–10.

12. Blomstrand E, Hassmen P, Ek S, et al. Influence of ingesting a solution of branched-chain amino acids on perceived exertion during exercise. Acta Physiol Scand 1997;159:41–9.

13. Blomstrand E, Hassmen P, Ekblom B, et al. Administration of branched-chain amino acids during sustained exercise-effects on performance and on plasma concentration of some amino acids. Eur J Appl Physiol 1991;63:83–8.

14. Scarna A, Gijsman HJ, Harmer CJ, et al. Effect of branch chain amino acids supplemented with tryptophan on tyrosine availability and plasma prolactin. Psychopharmacology 2002;159:222–3.