Response to vitamin D fortified food in rural white and American Indian women

The multiple positive health impacts of optimal vitamin D status are increasingly recognized, yet practical population-based solutions to improving vitamin D status, specifically in rural and American Indian (AI) populations, received little attention. Methods – This concept randomized double-blind trial examined serum 25-hydroxyvitamin D [25(OH)D] response to daily ingestion of low calorie chocolate disk with 2,500 IU of vitamin D₃ (D₃) or placebo (PBO) for 4 months in postmenopausal white and AI women from rural communities. All participants had serum 25(OH)D, serum and urinary calcium at baseline and months 1, 2 and 4. General linear model adjusted for age and baseline values was used to evaluate the treatment (D₃ vs. PBO) and ethnicity (white vs. AI) effects on changes in serum 25(OH)D concentrations. Results – At screening, 37% white and 65% AI women had low (<30 ng/ml) vitamin D status (p=0.02); 35 white and 28 AI women were randomized to receive vitamin D₃ or PBO. Total 25(OH)D concentrations increased by 17.1+/-1.9 ng/ml (white) and 12.1+/-2.7 ng/ml (AI) in groups receiving D₃ vs. PBO (p<0.01) over the study period. No significant changes in 25(OH)D concentrations were observed in PBO groups. There were no changes in mean serum calcium concentrations over the study period. Conclusion – Food fortification with greater amounts of vitamin D₃ is safe and effective to improve vitamin D status. There was no ethnicity effect on the 25(OH)D response to D₃-fortified food in this small study. However, prevalence of low vitamin D status was higher in the AI group.