Introduction: At the turn of the twentieth century, ultraviolet light was successfully used to treat tuberculosis of the skin. Upper respiratory tract infections had been inversely associated with sun exposure. [More sun, fewer infections.]
During the last decade, basic scientific research demonstrated that vitamin D has an important anti-infective role.
Method: Review of the relevant literature on the influence of vitamin D on innate immunity and respiratory tract infection.
Results: Vitamin D is involved in the production of defensins and cathelicidin - antimicrobial peptides that provide a natural defense against potential microbiological pathogens.
Vitamin D supplementation increases cathelicidin production.
Low vitamin D levels are associated with an increased incidence of upper respiratory tract infections.
Conclusions: Vitamin D appears to play an important role in the regulation of innate immunity in the upper respiratory tract. Optimal vitamin D levels and appropriate dosing schedules have yet to be determined.
Source: Journal of Laryngology and Otology, Jan 2010 ;13:1-5. PMID: 20067648, by Bartley J. Department of Otolaryngology-Head and Neck Surgery, Counties-Manukau District Health Board, Auckland, New Zealand.