Tuberculosis (TB) is a major global health problem and often coincides with nutritional deficiency. In fact, vitamin D deficiency has been reported among TB patients, and vitamin D receptor polymorphisms are associated with susceptibility to Mycobacterium tuberculosis. High doses of vitamin D were widely used to treat TB patients in the preantibiotic era. This approach was successful: vitamin D can suppress intracellular growth of M tuberculosis in vitro. Vitamin D also induced the expression of cathelicidin, which is involved in the first line of defense in TB patients. Thus, vitamin D may have a role in TB treatment, and further investigation is needed.