Using food fortification to improve vitamin D bioaccessibility and intakes.

Abstract

Vitamin D intakes and status are low in many countries due to seasonal UVB exposure variation and the fact that few foods are naturally vitamin D rich. Data modelling studies show that vitamin D intakes increase with food fortification, and countries with mandatory fortification policies have higher vitamin D intakes and status compared to countries without. While many foods can be vitamin D fortified, vitamin D bioavailability differs depending on fortification methods, food structure and composition. Randomised controlled trials (RCT) report that vitamin D2 bioavailability varies between foods, whereas vitamin D3 is bioavailable from many foods. In vitro studies suggest that altering the lipid composition of fortified foods increases vitamin D3 absorption. Olive oil increased vitamin D3 absorption during in vitro digestion compared to other dietary oils. Additionally, when vitamin D3 was incorporated into micelles formed from in vitro digestion of olive oil, more vitamin D3 was absorbed compared to other dietary oils. However, in a human postprandial study, a preformed vitamin D3 micelle dairy drink did not increase vitamin D3 absorption, and a vitamin D3 olive dairy drink increased vitamin D3 absorption in vitamin D insufficient participants only. Action is urgently needed to improve vitamin D intakes and status worldwide. Food fortification improves vitamin D intakes; however, fortification strategies unique to each country are needed. This review will synthesise the literature describing data modelling and intervention trials that assess the safety and efficacy of vitamin D fortification strategies, and those manipulating food composition to alter vitamin D bioavailability from fortified foods. Additionally, RCT examining the impact of vitamin D fortification strategies on vitamin D intakes and status over time are reviewed.