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}