Cathelicidin

Vitamin D is the primary regulator of the antimicrobial peptide cathelicidin, described as one of the body's most powerful antiviral weapons. EBV actively suppresses vitamin D receptors to prevent cathelicidin production, disarming this defense. A 2019 study (Beard, Nutrients) found vitamin D deficiency in 68% of EBV cases, with deficiency 100% associated with EBV viral load. This supports vitamin D supplementation to restore cathelicidin-mediated antiviral defense.