Note: wonder if this Greenland conclusion is associated with Inuit digestive systems which have evolved to repress vitamin D in the gut – due to too much vitamin D in blubber, etc. Have not noticed it reported elsewhere.
Both high and low serum vitamin D concentrations are associated with tuberculosis: a case-control study in Greenland.
Br J Nutr. 2010 Jun 17:1-5.
Nielsen NO, Skifte T, Andersson M, Wohlfahrt J, Søborg B, Koch A, Melbye M, Ladefoged K.
Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
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-gamma 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. PMID: 20553638