More recently, however, there has been a resurgence of interest in vitamin D as an effective adjunctive therapy in tuberculosis. Recent reports indicate that vitamin D may have a pronounced immunomodulatory role in the pathogenesis of tuberculosis within the human host. It is well known that areas of granulomatous inflammation in TB are sites of increased vitamin D production stemming from activated macrophages and Th1 lymphocytes within the granuloma Recently, the immunomodulatory function of increased vitamin D levels at sites of TB involvement has been demonstrated, in that 1,25(OH)2D, the active metabolite form of vitamin D, has been found to induce antimycobacterial activity in vitro in both monocytes and macrophages.