Effect of vitamin D and omega-3 fatty acid supplementation on anemia incidence among older adults: the VITAL trial.

Vitamin D and marine-derived long-chain n-3 (omega-3) fatty acids (FAs) may represent a novel intervention to prevent anemia of inflammation. We report the results of an ancillary study of the larger Vitamin D and Omega-3 Trial (VITAL), which looked at the effect of vitamin D and/or omega-3 FA supplementation on incidence of anemia in midlife and older adults. VITAL is a randomized, double-blinded, placebo-controlled trial, with a 2 × 2 factorial design. We focus on a subcohort of 839 participants without baseline anemia evaluated at the Boston Clinical and Translational Science Center. The primary end point was incidence of anemia (hemoglobin <13 g/dL for men, and <12 g/dL for women measured, at 2 years). The secondary end point was change in hemoglobin from baseline to 2 years. Incidence of anemia in our cohort was 9.3% over 2 years. Neither vitamin D nor omega-3 FAs had significant effect on anemia incidence (odds ratio [OR], 0.94 [95% confidence interval (CI), 0.59-1.51] and 1.31 [95% CI, 0.82-2.09], respectively) or change in hemoglobin from baseline to 2 years. There were no significant differences when stratified by race, sex, body mass index, or baseline vitamin D level. Omega-3 FAs had a statistically significant effect on change in hemoglobin in participants with baseline C-reactive protein >3 mg/L (P interaction = 0.047), whereas vitamin D had an effect in participants with lower than median baseline total fish intake (P interaction = .001). Supplementation with vitamin D or omega-3 FAs, or their combination, did not reduce incidence of anemia in midlife and older adults. The trial was registered at www.ClinicalTrials.gov as #NCT01169259.