Vitamin D deficiency is associated with anaemia among African Americans in a US cohort

Vitamin D deficiency is highly prevalent in the US population and is associated with numerous diseases, including those characterised by inflammatory processes. We aimed to investigate the link between vitamin D status and anaemia, hypothesising that lower vitamin D status would be associated with increased odds of anaemia, particularly anaemia with inflammation. A secondary aim was to examine the effects of race in the association between vitamin D status and anaemia. We conducted a cross-sectional analysis in a cohort of generally healthy adults in Atlanta, GA (n 638). Logistic regression was used to evaluate the association between vitamin D status and anaemia. Serum 25-hydroxyvitamin D (25(OH)D) < 50nmol/l (compared to 25(OH)D >= 50nmol/l) was associated with anaemia in bivariate analysis (OR 2.64, 95% CI 1.43, 4.86). There was significant effect modification by race (P=0.003), such that blacks with 25(OH)D < 50nmol/l had increased odds of anaemia (OR 6.42, 95% CI 1.88, 21.99), v. blacks with 25(OH)D >= 50nmol/l, controlling for potential confounders; this association was not apparent in whites. When categorised by subtype of anaemia, blacks with 25(OH)D < 50 nmol/l had significantly increased odds of anaemia with inflammation than blacks with serum 25(OH)D >= 50 nmol/l (OR 8.42, 95% CI 1.96, 36.23); there was no association with anaemia without inflammation. In conclusion, serum 25(OH)D < 50 nmol/l was significantly associated with anaemia, particularly anaemia with inflammation, among blacks in a generally healthy adult US cohort.