Peptides are short chains of amino acids that serve as signaling molecules in the body, and some are involved in immune regulation. There is growing scientific interest in the use of specific peptides to support the thymus, an organ critical for the maturation of T-lymphocytes (T-cells) which are essential for adaptive immunity. Thymic peptides, such as thymosin alpha-1, have been studied for their immunomodulatory properties. Clinical research has shown that thymosin alpha-1 can enhance immune responses in certain immunodeficiencies and infections, and it has been used as an adjunct therapy in some cancer and viral infection settings.

However, the evidence is strongest for specific, purified thymic peptides rather than generic "peptides" as a class. Most over-the-counter peptide supplements are not well characterized or standardized, and their ability to affect thymic function in humans remains largely unproven. The clinical studies that do exist typically involve prescription-grade thymic peptides administered under medical supervision. Thus, while there is a scientific rationale and some clinical evidence for the use of certain peptides to support thymus function, the generalization to all peptide supplements is not supported by current research.