Proprietary blends of amino acids and proteins are commonly marketed for injury support, particularly in the context of muscle recovery, wound healing, and tissue repair. The scientific rationale is based on the physiological roles of amino acids—especially essential amino acids, branched-chain amino acids (BCAAs), and specific proteins like collagen—in supporting the repair and regeneration of tissues after injury. Several clinical studies have demonstrated that protein supplementation can promote muscle protein synthesis, reduce muscle loss during immobilization, and improve recovery outcomes following surgery or trauma. For example, leucine, a BCAA, has a well-established role in stimulating muscle protein synthesis. Collagen peptides have shown some benefit in the healing of tendons and ligaments, though evidence is still emerging. However, the term "proprietary blend" is non-specific, and the efficacy depends heavily on the actual composition, dosage, and bioavailability of the included amino acids/proteins. While there is moderate scientific support for some amino acids and protein formulations in injury recovery, the evidence is less robust for generic or unspecified “proprietary blends.” Many blends include fillers or subtherapeutic doses that may not provide clinical benefit. Thus, while there is a scientific basis for targeted amino acid/protein supplementation in injury support, the strength of evidence for unspecified proprietary blends is moderate (3/5).