784 Danish children aged 8 to 11 years were part of a crossover trial where the intervention was school dinners formulated with an increase in fish content of 48%. The intervention failed to provide a useful increase in circulating in vitamin D levels, with intake levels still less than a third of that recommended by the Danish authorities.
784 Danish children from the OPUS School Meal study aged 8 to 11 years were part of a crossover trial (1) where the intervention was school dinners formulated with an increase in fish content of 48%. The vitamin D intake level for children of that age was recently increased from 7.5 μg/day to 10 μg/day in the Nordic Nutrition recommendations (2). The baseline intake levels in this study at baseline were just 1.7 and 2 μg/day for girls and boys respectively. The average fish intake increased by 48% during the intervention from a baseline intake of an average of just 9g/day. However, this represents just a 0.9 μg/day increase in vitamin D intake and had no overall significant effect of the serum circulating 25(OH)D status. There was increase of between 7% and 10% in the 25(OH)D status during the winter, but nothing at all during the summer. The study also measured a basket of musculoskeletal health biomarkers, but no changes were observed after the intervention, probably because the effective increase in intake was so small.
It was surprising to find such low intake levels of vitamin D in such a prosperous country as Denmark. When this fact is combined with the relatively low level of sunlight available to its citizens, it is clear that some form of vitamin D fortification/supplementation is going to be required in this population group if musculoskeletal problems are to be avoided in later life. This well conducted, large study implies that simple dietary changes cannot address the current levels of vitamin D deficiency and that some form of direct supplement intervention is required.
Denmark is not the only Northern European country to have vitamin D intake issues. In the UK, the government Scientific Advisory Committee on Nutrition (SACN) has just updated its recommendation of the vitamin D Reference Nutrient Intake (RNI) of 10 μg /day for all the population that are four years of age or older (3). The rationale for this is that a serum 25(OH)D concentration in the body should not fall below 25 nmol/L at any time of year if musculoskeletal health is to be maintained. (Previously, SACN said that only at-risk groups required supplementation (e.g., young children, the elderly, pregnant women and people with darker skins), but this change would suggest that almost all the population will require supplementation, particularly during the winter months when sunlight levels are low and hence synthesis in the skin is low.