Improved understanding of the association between
tuberculosis and
vitamin D is needed to inform clinical practice.
Vitamin D has both immunostimulatory and immunosuppressive effects relevant to human antimycobacterial responses. Ultraviolet radiation, the main source of
vitamin D, also induces
immunomodulation and could affect the relation between
vitamin D and
tuberculosis. Clinical trials of
vitamin D supplementation in patients with
tuberculosis have produced largely negative results, prompting the review of dosing regimens-an explanation for low
25-hydroxyvitamin D status in patients with active
tuberculosis is also needed. The reporting of
vitamin D deficiency needs to address assay inaccuracies, rising thresholds to define sufficiency, and scarce knowledge of the concentrations needed for optimum immune responses. Future research to measure the effect of the inflammatory setting on serum concentrations of
25-hydroxyvitamin D, at
tuberculosis diagnosis and during recovery, could help to account for
25-hydroxyvitamin D changes in these concentrations in patients with
tuberculosis. Studies into the role of
vitamin D supplementation in
latent tuberculosis justify clinical trials in this population, but pose methodological challenges.
Vitamin D trials in patients with active
tuberculosis should be done in well selected populations using adequate
vitamin D doses, although such doses remain undefined.