Very poor bioavailability of vitamin D2 from bread made with UV-irradiated yeast has implications for its ability to improve vitamin D status: new data from an ODIN

There is a considerable mismatch between current intakes of vitamin D by many European populations and recommended target intakes for the vitamin [1]. While traditional fortification of milk and other dairy products remains important in tackling inadequate intake, additional strategic approaches to fortification, including biofortification, of a wider range of foods, have the potential to increase vitamin D intakes in the population [2]. The potential to fortify bread with synthetic vitamin D3 has been known for some time, and fortified bread has been shown to increase vitamin D status as effectively as vitamin D supplements in adult women [3]. The process of treating baker’s yeast with UV light enriches it in vitamin D2 and thus opens up major potential for vitamin D2enhanced bread and other appropriate baked products. This vitamin D2-enriched UV-treated baker’s yeast was assessed by the EFSA Dietetic Products, Nutrition and Allergies (NDA) Panel in 2014 and was considered safe for use in yeast-leavened bread, rolls, fine pastry and food supplements [4]. Bread using this vitamin D-enriched UV-treated baker’s yeast has already made its way onto the market in some countries [5]. Data demonstrating that the vitamin D2 in bread made from this UVtreated baker’s yeast can increase vitamin D status has only come from a study in rats [6] thus far. One of the aims of the ODIN project was to investigate the bioavailability of vitamin D2 from UVirradiated yeast present in bread in an 8-week randomized controlled trial in healthy young adult women during winter.