Modelling vitamin D fortification scenarios for the Australian population

Low vitamin D status (circulating 25-hydroxyvitamin D [25(OH)D] concentration < 50 nmol/L) affects nearly one in four Australian adults(1). The primary source of vitamin D is sun exposure; however, a safe level of sun exposure for optimal vitamin D production has not been established. As supplement use is uneven, increasing vitamin D in food is the logical option for improving vitamin D status at a population level. The dietary supply of vitamin D is low since few foods are naturally rich in vitamin D. While there is no Australia-specific estimated average requirement (EAR) for vitamin D, the Institute of Medicine recommends an EAR of 10 μg/day for all ages. Vitamin D intake is low in Australia, with mean usual intake ranging from 1.8–3.2 μg/day across sex/age groups(2), suggesting a need for data-driven nutrition policy to improve the dietary supply of vitamin D. Food fortification has proven effective in other countries. We aimed to model four potential vitamin D fortification scenarios to determine an optimal strategy for Australia. We used food consumption data for people aged ≥ 2 years (n = 12,153) from the 2011–2012 National Nutrition and Physical Activity Survey, and analytical food composition data for vitamin D3, 25(OH)D3, vitamin D2 and 25(OH)D2(3). Certain foods are permitted for mandatory or voluntary fortification in Australia. As industry uptake of the voluntary option is low, Scenario 1 simulated addition of the maximum permitted amount of vitamin D to all foods permitted under the Australia New Zealand Food Standards Code (dairy products/plant-based alternatives, edible oil spreads, formulated beverages and permitted ready-to-eat breakfast cereals (RTEBC)). Scenarios 2–4 modelled higher concentrations than those permitted for fluid milk/alternatives (1 μg/100 mL) and edible oil spreads (20 μg/100 g) within an expanding list of food vehicles: Scenario 2—dairy products/alternatives, edible oil spreads, formulated beverages; Scenario 3—Scenario 2 plus RTEBC; Scenario 4—Scenario 3 plus bread (which is not permitted for vitamin D fortification in Australia). Usual intake was modelled for the four scenarios across sex and age groups using the National Cancer Institute Method(4). Assuming equal bioactivity of the D vitamers, the range of mean usual vitamin D intake across age groups for males for Scenarios 1 to 4, respectively, was 7.2–8.8, 6.9–8.3, 8.0–9.7 and 9.3–11.3 μg/day; the respective values for females were 5.8–7.5, 5.8–7.2, 6.4–8.3 and 7.5–9.5 μg/day. No participant exceeded the upper level of intake (80 μg/day) under any scenario. Systematic fortification of all foods permitted for vitamin D fortification could substantially improve vitamin D intake across the population. However, the optimal strategy would require permissions for bread as a food vehicle, and addition of higher than permitted concentrations of vitamin D to fluid milks/alternatives and edible oil spreads.