Vitamin D Deficiency and Tuberculosis Progression

Najeeha Talat; Sharon Perry; Julie Parsonnet; Ghaffar Dawood; Rabia Hussain

Disclosures

Emerging Infectious Diseases. 2010;16(5) 

In This Article

Conclusion

In this cohort follow-up study from Pakistan, low vitamin D levels were associated with progression to active TB disease in healthy household contacts. No deaths occurred during the follow-up period from either TB or unrelated causes. Our findings also suggest that vitamin D deficiency may explain the higher susceptibility of women to disease progression in our cohort. A high prevalence of vitamin D deficiency in female patients also was reported in ambulatory patients at Aga Khan University.[8] Factors such as low socioeconomic status, poor nutrition, traditional/cultural traits, and little exposure to sunlight may further explain vitamin D deficiency in female patients in this cohort. Despite several limitations to our study, such as information about diet, body mass index, exposure to sunlight and the relatively small number of study participants, our results are supported by a meta-analysis of 7 case-control studies in different ethnic populations (including an Indian population) that showed 70% of healthy controls had higher vitamin D levels than did untreated TB patients.[3] Previously in African immigrants in Melbourne, Victoria, Australia,[9] lower mean vitamin D levels were associated with high probability of latent, current, or past TB infection. Cross-sectional studies are needed in Pakistan to appreciate this association with sex and susceptibility to TB with larger sample size. Most of the South Asian population, including Pakistani immigrants to European countries and South Indians, had <10 ng/mL of serum vitamin D level[10] and is consistent with reports from Aga Khan Hospital.[8,11] Vitamin D plays an important role in activation of 1 α-hydroxylase to convert 25(OH) D to its active form [1, 25 (OH) 2D] that leads to expression of cathelicidin, a microbicidal peptide for Mycobacterium tuberculosis.[5,12] Serum levels >30 ng/mL provide an adequate substrate for the enzyme. Serum levels <20 ng/mL may therefore impair the macrophage-initiated innate immune response to M. tuberculosis and offer a possible explanation for geographic and ethnic[13] variations in susceptibility to TB.

Vitamin D supplementation during TB treatment remains controversial; a few studies have reported clinical improvement in pulmonary TB[14] and 1 study reported no effect.[15] However, our findings indicate that further studies should be conducted regarding use of vitamin D as a supplement for persons undergoing treatment for TB and those with latent TB infection.

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