Podcast episode 27 (in German)
LL-37: The body’s own defense peptide – or a driver of inflammation?
July 4, 2026
LL-37 is the only human cathelicidin: a defense peptide produced by the body that tears open the envelope of bacteria, disrupts biofilms and helps with wound healing. The episode shows why research values it, how vitamin D switches it on and when it drives inflammation itself.
What it is about
LL-37 is part of the innate immune defense and sits wherever outside meets inside: in skin, sweat, saliva and the mucous membranes of the lungs and gut. It is positively charged, attaches to the negatively charged envelope of bacteria and perforates it; bacteria have a hard time developing resistance against this physical mechanism. It also summons immune cells and promotes the formation of new blood vessels and wound healing. The episode also shows the downside: too much LL-37 in the wrong place drives inflammation, as in psoriasis and rosacea. The conclusion is a model for new antibiotics and a natural lever with the best data: a good vitamin D status.
Key points
- LL-37 consists of 37 building blocks and is the only human cathelicidin, while many animals have entire families of these defense peptides.
- Dürr and colleagues described LL-37 in Biochimica et Biophysica Acta in 2006 as a multifunctional peptide that kills pathogens, modulates immune responses and is involved in wound healing.
- A review by Vandamme and colleagues in 2012 summarized the diverse immunomodulatory functions, which go far beyond killing pathogens.
- The gene for LL-37 has a docking site for active vitamin D; your own status is shown by the 25-OH vitamin D level in the blood.
- In psoriasis and rosacea there is too much LL-37 in the wrong place; in atopic dermatitis, production in the skin is often too low.
- Research is being done in 3 fields: LL-37 variants against resistant germs, gels for chronic wounds, and cancer, where depending on the tissue it slows or promotes tumor cells.
- Dietary fiber and the butyrate formed in the gut promote the formation of such defense peptides in the intestinal mucosa; zinc plays a role in skin defense.
Where the data stop
The impressive data on LL-37 come predominantly from cell culture and animal models. Controlled human trials on self-administration are missing, as of July 2026. In the episode, the vitamin D route is considered one of the most plausible mechanisms behind the link between vitamin D and susceptibility to infection; it does not quantify how large the effect is in an individual.
As an injection, LL-37 is an unapproved research peptide from the gray market. In high concentrations it can irritate the body’s own cells, and anyone prone to psoriasis or rosacea should know that it can fuel exactly these processes. With such an active peptide, purity and the correct sequence are decisive. The simplest first step remains a vitamin D test; interpreting the value and any possible supplementation belong in a conversation with your physician.
Listen (in German)
Listen on Spotify Listen on Apple Podcasts Listen on Amazon Music
Published on July 4, 2026.
The topic in the database
- The body’s own defense classic: the only human cathelicidin, with broad antimicrobial action and a role in immunomodulation and wound…LL-37
All episodes in the app (German)
Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-10-09.