[Vitamin D and infectious diseases].

Vitamin D plays a role in the synthesis of antibacterial peptids and in autophagy. Several studies have shown that low levels of vitamin D are associated with the susceptibility and the severity of acute infections on one hand, and with an unfavorable outcome of some chronic infections (such as HIV infection). Vitamin D supplementation improves response to treatment of some viral (such as chronic hepatitis C infection) or bacterial infections (such as pulmonar tuberculosis). Vitamin D supplementation demonstrated no benefit in reducing the incidence of pulmonary infections. The target level of vitamin D to be reached after supplementation is not known yet.