Vitamin D and Rosacea
Rosacea is one of the few skin conditions where vitamin D supplementation has a plausible mechanistic downside as well as upside. Vitamin D upregulates cathelicidin (LL-37) — which is beneficial for infection defence but may also drive rosacea inflammation. Evidence is mixed and clinically complicated.
The cathelicidin story
Rosacea patients have elevated skin cathelicidin and abnormally processed LL-37 peptides. This drives erythema, papules, and inflammation. Vitamin D is a potent inducer of cathelicidin — a bit like adding fuel to a fire that's already going.
Observational data
Some studies find rosacea patients have HIGHER 25(OH)D than controls (Ekiz 2014); others find no significant difference. This is not the typical pattern seen in other inflammatory skin diseases.
Practical considerations
- Rosacea patients with documented vitamin D deficiency: correct to standard sufficient levels; don't over-supplement.
- If already sufficient, additional vitamin D is not recommended specifically for rosacea.
- UV exposure is a known rosacea trigger — don't attempt sun-based vitamin D strategies.
- Evidence-based rosacea therapy: metronidazole cream, ivermectin cream, azelaic acid, brimonidine, oral doxycycline, IPL.