Introduction
Sun exposure as a therapeutic approach to treat tuberculosis (TB) was used more than 100 y ago, before the identification of Mycobacterium tuberculosis as the causative agent for TB [1]. Exposure of children suffering from rickets and TB to artificial ultraviolet (UV) light resulted in a positive effect on both diseases. The use of sanatoria was also based on the belief that fresh air and sun exposure led to a positive outcome in the treatment of TB [2]. Vitamin D is a known immune modulator [3] that can improve cell-mediated immunity [4] and the phagocytic capacity of macrophages [5]. It also increases the production of antimicrobial peptides such as cathelicidin [5], which is part of the innate immune system that plays a critical role in the fight against TB. Recent research highlighted the production of cathelicidin through toll-like receptor pathway