At the end of winter 2023, 7 to 26 percent of the Dutch population had a vitamin D deficiency. This is evident from research by RIVM. Due to little sunlight in winter, the so-called vitamin D status (amount of vitamin D in the body) in the Netherlands is at its lowest. For this research, blood was examined from participants in the Lifelines cohort, a large population study in Northern Netherlands. Men had a deficiency more often than women, and with age, the amount of vitamin D in the blood increased. 

The research was recently published in the scientific journal European Journal of Clinical Nutrition (external link). It also shows that the Dutch population had a higher vitamin D status in March 2023 than in March 2011. Data on vitamin D status from 2011 show that the deficiency of vitamin D in the summer months decreases to 0 to 5 percent due to more sunlight. Therefore, it is expected that this will also apply to 2023. What the health effects are of a (yearly) short-term vitamin D deficiency in winter is still unclear. Furthermore, within the Lifelines cohort, no data was available on factors that could influence the increase in vitamin D intake compared to 2011. Think of supplement use or exposure to sunlight. These possible explanations cannot be substantiated from this study. In follow-up research, it is important to look at the influence of such factors.

Advice for supplement use

To ensure that everyone gets enough vitamin D, the Health Council advises certain groups to use a vitamin D supplement. This supplementation advice applies, among others, to women over fifty years and men over seventy years. These groups had the most vitamin D in their blood, as this RIVM research shows. Possibly, the last adjustment of the supplementation advice by the Health Council in 2012 is one of the explanations for the higher vitamin D status in 2023 compared to 2011. Whether this actually means that they have followed the supplementation advice cannot be said based on the data in this research. The latest Food Consumption Survey (VCP) (external link) shows that women use supplements more often than men. This could partly explain the higher vitamin D status in women. 

Population study Northern Netherlands

The Lifelines cohort is a large population study in Groningen, Friesland, and Drenthe. Within this research, participants of different ages and backgrounds are followed for a longer period. For this research, RIVM looked at a group of adult participants from whom blood was taken in March 2023. Within the Lifelines cohort, the amount of vitamin D in the blood had been measured once before, namely in 2011. This data could be used to compare the results of 2023. 

Recommendations for further research

In addition to research on the health effects of a short-term vitamin D deficiency and factors that contribute to vitamin D status, research on the vitamin D status of other groups with a supplementation advice is also desired. Think of pregnant women and adults with darker skin. RIVM is currently preparing, at the request of the Ministry of VWS Ministry of Health, Welfare and Sport (Ministry of Health, Welfare and Sport), research into the vitamin D status of these groups. In addition, RIVM is also researching the adherence to the supplementation advice. It is possible that the results of this, in combination with the results of this research on vitamin D status, will lead to recommendations for adjustments in policy or the way of information dissemination.