In humans, vitamin D is formed in the skin following its exposure to sunlight. In comparison to the body's own formation of vitamin D, dietary consumption generally makes up only a relatively small proportion of the vitamin D supply to the body. While an overdose resulting from the body's own production is not possible, it certainly can result from the consumption of high doses of vitamin D - such as via certain food supplements.
An overdose of this kind leads to elevated calcium values in blood serum (hypercalcemia). The clinical symptoms associated with hypercalcemia in humans range from fatigue and muscular weakness to vomiting and constipation, and can even lead to cardiac arrhythmias and the calcification of blood vessels. If persistent, hypercalcemia can lead to kidney stones, kidney calcification and, ultimately, to a loss of renal function.
Even without exposure to sunlight, a daily consumption of 20 μg of vitamin D is adequate to meet the body's needs for this vitamin for the vast majority (97.5%) of the population.
The European Food Safety Authority (EFSA) has set a UL value (tolerable upper intake level) of 100 μg for vitamin D. According to the latest scientific research, if adults and children aged eleven and older consume a daily quantity of no more than 100 μg, any impairments to health are unlikely. This UL value includes the intake of vitamin D from all sources, and thus includes intake from supplements, normal dietary intake and intake from food that has been fortified with vitamin D. If high-dose vitamin D preparations are also consumed, this figure may be exceeded in combination with other sources of the vitamin.
From the perspective of nutritional science, the daily consumption of vitamin D preparations containing a 50 μg or 100 μg dose is not necessary. On the other hand, the BfR considers it unlikely that impairments to health will result from the occasional consumption of such high-dose preparations. If such high-dose vitamin D products are consumed on a daily basis over a longer period of time, however, the latest research does point to an elevated risk to health.
The BfR notes that, given an adequate length of time spent outdoors with corresponding exposure of the skin to sunlight, plus a balanced diet, an adequate supply of Vitamin D can be achieved by individuals without having to take vitamin D preparations. Individuals in risk groups for which a serious lack of vitamin D or a vitamin deficiency requiring medical intervention may be more likely to occur, should first clarify any need to take such preparations with their attending physician or general practitioner.
This opinion does not constitute a decision as to whether or not a product should be classified as a foodstuff, nor should it be interpreted as such.