Natural vitamin D in foods: To what degree does 25‐hydroxyvitamin D contribute to vitamin D activity of food?

Vitamin D3, vitamin D2, 25‐hydroxyvitamin D3 and 25‐hydroxyvitamin D2 constitute the vitamin D activity in foods. In general, vitamin D activity in foods depends on the content of fat, the feed the animals have been fed and the exposure of UVB. There are many gaps in our knowledge of 25‐hydroxyvitamin D in foods, the content and the amount in the dietary intake. We aimed to assess the content of the vitamin D vitamers in foods (eggs, milk, dairy products, chicken, veal, beef, and pork) on the Danish market using accredited analytical methods. We then combined these data with existing Danish data as well as with the information from the Danish Dietary Survey to estimate the dietary intake of vitamin D3 and of 25‐hydroxyvitamin among Danes. We report the level of vitamin D in 10% minced pork from free‐range pigs slaughtered in summer to 1.39 μg vitamin D3/100 g and 0.40 μg 25‐hydroxyvitamin D3/100 g, which are significantly higher (p < 0.001), than in early spring. Contents of vitamin D2 and 25‐hydroxyvitamin D2 are primarily <0.05 μg/100 g, though in beef up to 0.14 μg/100 g. 25‐hydroxyvitamin D3 accounts for up to 100% in veal to 8% in fat from from free‐range pigs. In the Danish diet, the share of 25‐hydroxyvitamin D3 is 24% for children (4–17 years) and 18% for adults (18‐75 years). Changes in feeding strategy in the primary sector could change the share of 25‐hydroxyvitamin D3 to 11 and 12% if extra vitamin D3 is in the feed, and sun or UVB‐exposure are used, while replacing vitamin D3 by 25‐hydroxyvitamin D3 in the feed may result in a share of 25‐hydroxyvitamin D3 of 52% and 40%, respectively, in children and adults. These estimates are based on the assumption that vitamin D3 and 25‐hydroxyvitamin D3 contribute equally to the vitamin D activity.