What does LL-37 do? Benefits and evidence

LL-37 is part of the body's early defense against microbes. Three small wound trials tested it on ulcers; the largest found no overall healing benefit. A tiny melanoma study injected it into tumors, and two COVID studies used bacteria engineered to make it. These studies do not validate routine injections under the skin. Inflammation, reproductive effects and tumor signals are key unresolved risks.

• In a small trial on leg ulcers, the two lower strengths improved early healing, though a larger trial found no overall benefit. (Studied in a trial)
• In a small foot-ulcer trial in diabetes, it helped healthy new tissue form in the wound, but wound size did not shrink more. (Studied in a trial)
• In lab and animal studies, it helped new blood vessels grow. (animal)
• Forum users report injecting it for infection, gut or immune goals; one reported improvement, without giving a dose. (Reported by users)

Uses in the sources

• Studied on chronic venous and diabetic foot ulcers. The larger venous-ulcer trial found no overall benefit; a small foot-ulcer trial improved a tissue-growth score. (Studied in a trial) (source)
• Exploratory melanoma research used injections directly into tumors. Four enrolled and only three appeared in posted results. (Studied in a trial) (source)
• COVID studies used engineered L. lactis capsules, not purified LL-37. The randomized study did not improve viral clearance overall. (Studied in a trial) (source)
• Forum users discuss injections for infection, gut or immune goals. No controlled human subcutaneous trial was found. (Reported by users) (source)