Improvement of vitamin D status through consumption of either fortified food products or supplement pills increased hemoglobin concentration in adult subjects: Analysis of pooled data from two randomized clinical trials

Background: It is documented that vitamin D may have a role in erythropoiesis as its deficiency is accompanied by an increased risk of anemia. Aim: This study aimed to examine whether improvement of vitamin D status through daily consumption of either fortified foods or supplements could impinge on certain hematologic parameters in adults. Methods: We pooled data from our two separate clinical trials and made five experimental groups. As part of their usual diet, one group consumed 500 mL/day of yogurt drink fortified with 1000 IU of vitamin D (D-yogurt, n = 27) whereas one group consumed 500 mL/day of the plain yogurt drink (P-yogurt, n = 27). In addition three other groups consumed either 50 g/day bread fortified with 1000 IU of vitamin D (D-bread) or supplement containing 1000 IU vitamin D (D-supplement, n = 27) or placebo (placebo, n = 27). Biochemical measurements were performed before and after the intervention. Results: In all three vitamin D-supplemented groups, serum 25(OH)D concentration increased after the intervention period, which was interestingly accompanied by a significant increment of hemoglobin (D-yogurt, p < 0.001, D-bread, p = 0.003, D-supplement, p < 0.001). Analyses indicated that among participants in vitamin D-intervention groups, being in D-yogurt group was more favourable predictor of improvement in hemoglobin concentrations compared with the placebo (p < 0.001), D-bread (p = 0.045) and P-yogurt (p = 0.001). Conclusion: Improvement of vitamin D status via regular intake of either vitamin D-fortified food products or supplements can result in a significant increment of hemoglobin in adult subjects. This finding has very important clinical as well as public health implications.