Modelling vitamin D food fortification among Aboriginal and Torres Strait Islander peoples in Australia

The colonisation of Australia around 250 years ago resulted in significant disruptive changes to the lifestyle and diet of Aboriginal and Torres Strait Islander peoples. Traditional foods high in micronutrients, including vitamin D, have been largely replaced with energy-dense foods (1) . Sun exposure—a primary source of vitamin D—may be reduced due to changes in clothing and housing structure (2) . Consequently, there is a high prevalence of vitamin D deficiency (serum 25-hydroxyvitamin D concentration < 50 nmol/L) and low vitamin D intake among Aboriginal and Torres Strait Islander peoples (2,3) . There is a need for a public health strategy to improve vitamin D status. Since few foods naturally contain vitamin D (e.g., fish, eggs, and meat), food fortification could be a suitable public health strategy to increase vitamin D intake without changing consumption behaviour. In Australia, besides food mandated for fortification (e.g., edible oil spreads), few foods permitted for voluntary fortification are routinely fortified. We aimed to model vitamin D food fortification scenarios among Aboriginal and Torres Strait Islander peoples. We used nationally representative food consumption data from the 2012–2013 National Aboriginal and Torres Strait Islander Nutrition and Physical Activity Survey (n = 4,109) and analytical vitamin D food composition data (4) to model four food fortification scenarios. Scenario 1 modelled the addition of the maximum permitted amount of vitamin D to all foods permitted for fortification in Australia: i) dairy products and alternatives, ii) butter/margarine/oil spreads, iii) formulated beverages (e.g., water with added sugar, vitamins and minerals), and iv) selected ready-to-eat breakfast cereal. Scenarios 2a–c included vitamin D concentrations higher than permitted in fluid milks/alternatives (1 μg/day) and butter/margarine/oil spreads (20 μg/day). Scenario 2a: i) dairy products and alternatives, ii) butter/margarine/oil spreads, iii) formulated beverages. Scenario 2b: as per Scenario 2a plus selected ready-to-eat breakfast cereals. Scenario 2c: as per Scenario 2b plus bread (not permitted for vitamin D fortification in Australia). Vitamin D fortification of a range of staple foods could potentially increase vitamin D intake among Aboriginal and Torres Strait Islander peoples by ~3–6 μg/day. Scenario 2c showed the highest potential median vitamin D intake increase from baseline of 2 μg/day to ~8 μg/day. Across all scenarios, the vitamin D intake of all participants remained below the Australian Tolerable Upper Intake Level of 80 μg/day. Our findings demonstrated that vitamin D fortification of a range of staple foods could potentially increase vitamin D intake among Aboriginal and Torres Strait Islander peoples in Australia. However, the most impactful vitamin D fortification strategy (Scenario 2c) would require a revision of the Australia New Zealand Food Standards Code to permit the addition of higher amounts of vitamin D than currently permitted and the inclusion of bread as a food vehicle for fortification.