Vitamin D and Tuberculosis
TB was the disease that first taught medicine about sun and vitamin D — 19th-century Alpine sanatoria used sunbathing as therapy long before the mechanism was understood. Vitamin D-dependent macrophage killing of Mycobacterium tuberculosis is now well-characterised biology, but modern adjunctive trials give a mixed picture.
The mechanism
TLR2/1 recognition of mycobacterial lipoproteins induces macrophage 1α-hydroxylase and VDR. Local calcitriol drives cathelicidin expression and phagosome-lysosome fusion, killing intracellular bacilli. Vitamin D-deficient macrophages have impaired killing — a plausible reason TB historically hit malnourished, sun-deprived populations hardest.
Modern adjunctive trials
- Martineau 2011 (UK) — 146 pulmonary TB patients; 100,000 IU cholecalciferol every 2 weeks × 4 doses added to standard antibiotics. Faster sputum-culture conversion in the tt TaqI VDR genotype subgroup.
- Salahuddin 2013 (Pakistan) — 259 TB patients; vitamin D repletion accelerated chest X-ray improvement.
- Cochrane 2020 review — vitamin D as TB adjunct: modest benefit in specific subgroups, no consistent improvement in cure rates overall.
Isoniazid and vitamin B6
Isoniazid (the "H" in RIPE/HRZE regimens) depletes vitamin B6 and can cause peripheral neuropathy. All patients on isoniazid should receive pyridoxine 25-50 mg/day. This is not a vitamin D issue but is worth knowing for TB patients on treatment. See our B6 page.
Hypercalcaemia risk
Active TB is a granulomatous disease — extra-renal 1α-hydroxylase in granulomatous lesions can produce unregulated calcitriol. Vitamin D supplementation in active TB carries small hypercalcaemia risk; monitoring calcium is prudent, especially with high-dose regimens. See our sarcoidosis page for the same principle.
Practical approach
- Standard TB treatment (RIPE: rifampin, isoniazid, pyrazinamide, ethambutol) remains primary.
- Correct vitamin D deficiency in active TB patients — 1,000-2,000 IU/day cholecalciferol; monitor calcium.
- Add pyridoxine 25-50 mg/day for isoniazid neuropathy prevention.
- Public health: address latent TB in vitamin D-deficient populations (test-and-treat programmes).