We receive free products and receive commissions through our links. See disclosures page. Once a niche athletic supplement, branched-chain amino acids (BCAAs) have exploded in popularity as a means to potentially improve muscle retention, endurance, and focus during workouts. (5) Now as synonymous with supplementation as the best protein powders and pre-workouts, the best BCAA supplements offer key benefits encased in flavorful profiles at affordable costs.