Branched-Chain Amino Acids for Sports & Fitness

Some athletes say that branched-chain amino acids helps improve strength-training and endurance results.

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.

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}

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.

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.