Both high and low serum vitamin D concentrations are associated with tuberculosis: a case-control study in Greenland

• Published in: British Journal of Nutrition
• Main Authors: Nielsen, Nina Odgaard, Skifte, Turid, Andersson, Mikael, Wohlfahrt, Jan, Søborg, Bolette, Koch, Anders, Melbye, Mads, Ladefoged, Karin
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2010
• Subjects: Adolescent; Adult; Aged; Case-Control Studies; Child; Female; Greenland; Humans; Inuits; Male; Middle Aged; Tuberculosis; Pulmonary; Vitamin D; Young Adult; greenlander*; inuits
• Online Access: https://portal.findresearcher.sdu.dk/da/publications/31426c7e-11d1-49ea-87aa-81e293b3402b; https://doi.org/10.1017/S0007114510002333

Vitamin D deficiency has been associated with increased risk of tuberculosis (TB). Changes from a traditional to a Westernised diet among Greenlanders have resulted in reduced serum vitamin D, leading to considerations of whether preventive vitamin D supplementation should be introduced. The association between vitamin D status and TB was examined to assess the feasibility of vitamin D supplementation in Greenland. This was examined in a case-control study involving seventy-two matched pairs of TB patients (cases) and controls aged 8-74 years. Cases were diagnosed with TB during 2004-6 based on clinical findings in combination with either (1) positive Mycobacterium tuberculosis culture, (2) characteristic X-ray abnormalities together with a positive tuberculin skin test or a positive interferon-γ release assay or (3) characteristic histology. Controls were individually matched on age ( ± 5 years), sex and district. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured and OR of TB were the outcome. Compared with individuals with 25(OH)D concentrations between 75 and 140 nmol/l, individuals with concentrations <75 nmol/l (OR 6.5; 95% CI 1.8, 23.5) or > 140 nmol/l (OR 6.5; 95% CI 1.9, 22.2) had higher risks of active TB (P = 0.003; adjustment for alcohol and ethnicity). Supplementing individuals with low vitamin D to normalise serum 25(OH)D concentrations was estimated to result in a 29% reduction in the number of TB cases. The study indicated that vitamin D supplementation may be beneficial to individuals with insufficient vitamin D concentrations but may increase the risk of TB among individuals with normal or high concentrations.