Gut & Immune Health

LL-37 (Cathelicidin)

A naturally occurring human antimicrobial peptide — your body already makes it. Supplementation supports innate immune defense against bacterial, viral, and fungal pathogens.

EvidenceCategory 2

Mechanism of Action

LL-37 is the only cathelicidin antimicrobial peptide found in humans. It disrupts microbial cell membranes, modulates innate immune responses, promotes wound healing, and has anti-biofilm properties. It bridges innate and adaptive immunity by recruiting immune cells to infection sites and modulating inflammatory responses.

Why It Matters for Women

Women face unique infection risks throughout life — urinary tract infections, vaginal infections, and post-surgical infections are all areas where antimicrobial peptide support may be relevant. LL-37 production can decline with vitamin D deficiency (common in women) and aging, potentially contributing to increased infection susceptibility.

Key Finding: LL-37 is the only human cathelicidin — a naturally occurring antimicrobial that your body produces. Supplementation supports the innate immune defense that declines with age.
Vandamme D, et al. Cell Immunol. 2012;280(1):22-35. PMID: 23246832

Side Effects & Safety

As a Category 2 peptide, LL-37 has limited human safety data from controlled trials. Its status as a naturally occurring human peptide suggests baseline tolerability, but therapeutic dosing data is limited. Injection site reactions are possible.

Where to Buy

BioPure Peptides
Direct product link

Frequently Asked Questions

Is LL-37 safe?

LL-37 is a naturally occurring human peptide, which is generally a positive safety signal. However, it is classified as Category 2 by the FDA, meaning limited human safety data from controlled trials. Discuss with your provider.

Why is LL-37 Category 2?

The FDA classified LL-37 as Category 2 due to limited human clinical safety data, not due to demonstrated safety concerns. This means it faces additional regulatory scrutiny for compounding.

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Medical Disclaimer: This profile is for educational purposes only. Always consult a licensed healthcare provider before starting any peptide therapy.

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