Amino Acid Complex from Thorne (1 scoop a day between meals) is a well-researched high-leucine blend of all essential amino acids that supports sports, fitness, and training-related activities and promotes the growth of muscle mass in individuals who need to preserve it, including the elderly. This is an especially important supplement for vegans. You can also take BCAA by Pure Encapsulations, 3,000 mg or 1 scoop a day.