Development of a model for optimal food fortification: vitamin D among adults in Finland

Average vitamin D intake is low in Finland. Even though almost all retail milk and margarine are fortified with vitamin D, the vitamin D intake is inadequate for a significant proportion of the population. Consequently, expanded food fortification with vitamin D would be motivated. However, there is a risk of unacceptably high intakes due to the rather narrow range of the adequate and safe intake. Therefore, a safe and efficient food fortification practice should be found for vitamin D.

To develop a model for optimal food fortification and apply it to vitamin D.

The FINDIET 2002 Study (48-h recall and data on supplement use (n = 2007), and 3 + 3 days’ food records, n = 247) was used as the test data. The proportion of the population whose vitamin D intake is between the recommended intake (RI) and the upper tolerable intake level (UL) was plotted against the fortification level per energy for selected foods. The fortification level that maximized the proportion of the population falling between RI and UL was considered the optimal fortification level.

If only milk, butter milk, yoghurt and margarine were fortified, it would be impossible to find a fortification level by which the intake of the whole population would lie within the RI-UL range. However, if all potentially fortifiable foods were fortified with vitamin D at level 1.2–1.5 µg/100 kcal, the intake of the whole adult population would be between the currently recommended intake of 7.5 µg/d and the current tolerable upper intake level of 50 µg/day (model 1). If the RI was set to 40 µg/day and UL to 250 µg/day, the optimal fortification level would be 9.2 µg/100 kcal in the scenario where all potentially fortifiable foods were fortified (model 2). Also in this model the whole population would fall between the RI-UL range.

Our model of adding a specific level of vitamin D/100 kcal to all potentially fortifiable foods (1.2–1.5 µg/100 kcal in model 1 and 9.2 µg/100 kcal in model 2) seems to be an efficient and safe food fortification practise.