Correction of vitamin D inadequacy by food fortification

Food fortification with vitamin D exceeding currently utilized amounts is a logical approach to improve vitamin D status at the population level. Methods – This randomized double-blind trial examined serum 25-hydroxyvitamin D [25(OH)D] response to daily ingestion of a low calorie chocolate disk with ~2,200 IU of vitamin D₃ or placebo (PBO) for 4 months in women aged 20-30 years (n=31), 55-65 years (n=34) and 75+ years (n=34). All participants had 24-hour urinary calcium, serum calcium and serum 25(OH)D measured at baseline and months 1, 2 and 4. Data were analyzed using general linear model by age and treatment group adjusted for baseline 25(OH)D levels and BMI. Results – Baseline mean 25(OH)D levels did not differ between D₃ or PBO groups with the overall mean±SE equal 29.5±1.1 ng/ml. At baseline, 45% had suboptimal vitamin D status, defined as a 25(OH)D concentration < 30 ng/ml, with greater proportion (52%) among postmenopausal women compared to younger (27%) women (p<0.05). The 25(OH)D concentration increase at month 4 was 14.1 ng/ml in women receiving vitamin D fortified food, however 11% remained below 30 ng/ml. Serum and 24-hour urinary calcium were unaffected by intake of vitamin D fortified food. Age-group effect on the 25(OH)D increase was insignificant. Conclusion – Food fortification with 2,200 IU of vitamin D₃ is safe, effective and increases serum 25(OH)D levels similar to supplements. The daily vitamin D requirement likely exceeds 2,200 IU to assure optimal levels for all women, especially for those who are 55 years or older.