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 D 3 , 25(OH)D 3 , vitamin D 2 and 25(OH)D 2 (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.