Vitamin D Toxicity

The adverse effects of high vitamin D intakes– do not occur at these new recommended intake levels. In fact, it is worth noting that the recommended intakes for all age groups are still well below the lowest observed adverse effect level of 50 μg/day and have not yet even reached the no observed adverse effect level of 20 μg/day. Outbreaks of idiopathic infantile hypercalcemia in the United Kingdom in the post–World War II era led to the withdrawal of vitamin D fortification from all foods in that country because of concerns that they were due to hypervitaminosis D. 

There are some suggestions in the literature that these outbreaks of idiopathic infantile hypercalcemia may have been multifactorial with genetic and dietary components and were not just due to technical problems with over-fortification as was assumed. In retrospect, the termination of the vitamin D fortification may have been counter productive because it exposed segments of the UK community to vitamin deficiency and may have discouraged other nations from starting vitamin D fortification programmes. This is all the more cause for concern because hypovitaminosis D is still a problem worldwide, particularly in developing countries at high latitudes and in countries where skin exposure to sunlight is discouraged.

References:

National Academy of Sciences. 1997. Report on Dietary Reference Intakes for Calcium, Phosphorus, Magnesium and Vitamin D, Food & Nutrition Board, Institute of Medicine, US National Academy of Sciences. P. 7.1-7.30. . National Academy Press.

Lachance, P.A. 1998. International Perspective: Basis, need and application of recommended dietary allowances. Nutr. Revs., 56: S2-S5.

Jones, K.L. 1990. Williams syndrome: an historical perspective of its evolution, natural

history, and etiology. Am. J. Med. Genet. Suppl., 6: 89-96.

Fraser, D. 1967. The relation between infantile hypercalcemia and vitamin D – public health implications in North America. Pediatr., 40: 1050-1061.

Mawer, E.B. & Davies, M. 1997.Vitamin D deficiency, rickets and osteomalacia, a returning problem worldwide. In: Vitamin D. Chemistry, Biology and Clinical Applications of the Steroid Hormone. p. 899-906. Norman AW, Bouillon R, Thomasset M eds. University of California.