L-Lysine

No evidence from these studies that it treats cold sores, builds muscle, or boosts immunity. Not shown to reduce anxiety or improve bone density in the provided research. Don't assume 'essential amino acid' means supplementing it does anything special if your diet already provides enough protein.

• The provided studies do not include human clinical trials testing oral L-lysine supplements for any specific health benefit — most papers involve industrial, food science, or materials science applications of lysine or poly-lysine derivatives.
• Many supplements combine L-lysine with other ingredients (e.g., collagen, hyaluronic acid, vitamin C), making it impossible to attribute any effect to lysine alone.
• L-lysine sulfate evaluated in one paper was assessed for animal feed safety, not human supplementation — do not conflate animal feed research with human health benefits.
• High-dose lysine supplementation may interact with arginine metabolism; no safety ceiling for supplemental doses is established from the provided data.