Some research has shown that supplemental branched-chain amino acids (BCAA) (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, BCAA 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.^11,3,13

Some research has shown that supplemental branched-chain amino acids (BCAA) (typically 10 to 20 grams per day) do not result in meaningful changes in body composition,¹³ nor do they improve exercise performance or enhance the effects of physical training.^{14,15,16,17,18,19} However, BCAA supplementation may be useful in special situations, such as preventing muscle loss at high altitudes and prolonging endurance performance in the heat.^20,21 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, BCAA 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.²² Studies by one group of researchers suggest that BCAA supplementation may also improve exercise-induced declines in some aspects of mental functioning.^23,15,25

Some research has shown that supplemental branched-chain amino acids (BCAA) (typically 10 to 20 grams per day) do not result in meaningful changes in body composition,²⁵ nor do they improve exercise performance or enhance the effects of physical training.^{26,27,28,29,30,31} However, BCAA supplementation may be useful in special situations, such as preventing muscle loss at high altitudes and prolonging endurance performance in the heat.^32,33 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, BCAA 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.³⁴ Studies by one group of researchers suggest that BCAA supplementation may also improve exercise-induced declines in some aspects of mental functioning.^35,27,37