Vitamin d and inflammation status in postmenopausal American Indian women

Low vitamin D (D) status is common worldwide; it adversely affects bone health and may have multiple detrimental consequences including increased rates of chronic disease potentially mediated via effects on systemic inflammation. The relationship between vitamin D and inflammation status in American Indian (AI) populations has received very limited study. This is the first randomized controlled trial to test the effect of D supplementation on systemic markers of inflammation in AI women. Community-dwelling postmenopausal women (n=99) were recruited at a tribal clinic in northern Wisconsin for the 6 month trial. At baseline, women were 60.8±7.3 (±SD) years old with BMI of 33.1±7.0 kg/m²; 46% reported using multivitamin or D supplements. D levels were low: screening mean serum 25-hydroxyvitamin D [25(OH)D] was 24.8±11.3 ng/mL; 7% of women had 25(OH)D ≤10 ng/mL, 33% (10.1 to 19.9 ng/ml), 30% (20 to 29.9 ng/ml), and 31% (≥30 ng/mL). The prevalence of D insufficiency (<20 ng/ml) was 39% and similar to our earlier data for AI women from Minnesota. Compared to NHANES data, prevalence of low D for AI women is between that for white (20%) and Mexican American women (48%). The 25(OH)D levels were unrelated to BMI. Baseline c-reactive protein (CRP) was high 4.6±4.9 mg/L and was positively correlated (p<0.01) with 25(OH)D. In conclusion, D inadequacy is common in AI women, is associated with elevated CRP but not BMI. Work is ongoing to determine the effect of D supplementation on inflammation, and will assist AI communities in developing further interventions to reduce chronic disease.