Vitamin A deficiency linked with TB in household contacts of patients

Findings published in Clinical Infectious Diseases indicated that vitamin A deficiency was strongly predictive of tuberculosis among Peruvians who lived in households with patients who already had the disease.

“Multiple lines of evidence suggest that the association between socioeconomic status and TB may be mediated through nutritional status,” Omowunmi Aibana, MD, MPH, of the division of general internal medicine at the University of Texas Health Science Center, Houston, and colleagues wrote. “Although multiple studies document micronutrient deficiencies in people with TB disease, few prospective studies have assessed preexisting nutritional status as a determinant of progression from TB infection to disease. Despite the lack of data on TB risk, multiple previous studies support the role of vitamin A in immune responses to infection.”

Aibana and colleagues performed a case-control study of 6,751 residents of Lima, Peru, who were household contacts of patients with TB. The researchers defined cases as household contacts who did not have HIV and who developed TB 15 days or more after being enrolled. Aibana and colleagues matched each case with four controls who were randomly selected from household contacts without TB, then estimated the odds ratios for TB by carotenoid and vitamin A levels using conditional logistic regression. A total of 192 participants developed secondary TB during follow-up, the researchers reported. Aibana and colleagues evaluated 180 cases and 709 matched controls.

Patients with vitamin A deficiency were at a 10-fold increased risk for TB (adjusted OR = 10.53; 95% CI, 3.73-19.7), the researchers reported. Aibana and colleagues noted that TB risk increased with every decreased quartile of vitamin A levels.

“We find that vitamin A levels among persons exposed at home to a TB patient strongly predicted incident TB disease within 12 months of follow-up in a dose-dependent manner,” the researchers wrote. “In the event that the association between vitamin A deficiency and tuberculosis progression proves to be causal, routine vitamin A supplementation among persons at high risk for developing TB disease may provide an inexpensive, safe and effective means of preventing progression from TB infection to TB disease.” – by Andy Polhamus

Disclosure: The researchers report no relevant financial disclosures.