Vitamin D: should the supply in the Danish population be increased?

Abstract

A working group was established to evaluate the need for an increased vitamin D intake in the Danish population. Vitamin D is primarily important for calcium homeostasis, calcium absorption in the intestine and calcium content in bones, and thereby for the strength of the bones. Only a few foods provide vitamin D and the intake in the Danish population is low compared to the recommendation. However, vitamin D is also produced by the skin from solar exposure. How much vitamin D is provided this way is not known but it is said to be the most important source. Measures of vitamin D status and clinical signs of vitamin D status are therefore important when assessing the possible need for increased vitamin D intake. Measures of vitamin D status have shown a low status in the elderly but not in the young. More than 50% of nursing-home residents have low blood vitamin D levels and many have biochemical signs of osteomalacia. Vitamin D deficiency increases the risk of osteoporosis. In Denmark, for instance, 13 000 admissions each year are caused by hip fractures alone, almost all among elderly people. Dark-skinned women often constitute a problem with respect to vitamin D sufficiency because of reduced production from the skin secondary to extensive covering, skin pigmentation and many hours spent indoors. It is concluded that the elderly and dark-skinned (veiled) women will benefit from an increased vitamin D supply. Four strategies to increase vitamin D supply were considered: dietary changes, increased solar exposure, dietary supplements with vitamin D and food fortification with vitamin D. It is concluded that the best solution is to recommend dietary supplements with vitamin D to elderly over 65 years, dark-skinned and veiled women and people who, because of disease, are unable to spend time outdoors.