The bioavailability of vitamin D from fortified cheeses and supplements is equivalent in adults

Abstract

There is a need to increase the options for vitamin D fortification. We have developed a method to fortify hard cheese with vitamin D. Our aim was to characterize the bioavailability of vitamin D from fortified cheeses. Eighty adults were randomized to weekly servings of fortified cheddar cheese (DC) (34 g; n = 20); fortified low-fat cheese (DLF) (41 g; n = 10); liquid vitamin D supplement (1 mL), taken with food (DS+) (n = 20) or without food (DS-) (n = 10); placebo cheddar cheese (n = 10); or placebo supplement (n = 10). The treatments contained 28,000 IU cholecalciferol (vitamin D3), equivalent to 4000 IU (100 microg/d). The primary outcome was the comparison of vitamin D bioavailability, as measured by the serum 25-hydroxyvitamin D [25(OH)D] response, between fortified cheeses and supplement. In the placebo groups, initial 25(OH)D, 55.0 +/- 25.3 nmol/L, declined over the 8-wk winter protocol, to 50.7 +/- 24.2 nmol/L (P = 0.046). In the vitamin D-treated groups, the mean increases in 25(OH)D over 8 wk were: 65.3 +/- 24.1 (DC), 69.4 +/- 21.7 (DLF), 59.3 +/- 23.3 (DS+), and 59.3 +/- 19.6 nmol/L (DS-); these changes differed from the placebo groups (P < 0.0001) but not from one another (P = 0.62). Compared with baseline, serum parathyroid hormone decreased with both fortification (P = 0.003) and supplementation (P = 0.012). These data demonstrate that vitamin D is equally bioavailable from fortified hard cheeses and supplements, making cheese suitable for vitamin D fortification.