FOR MORE than 40 years it has been known that vitamin D is essential for maintenance of normal calcium metabolism in man. Efforts over this period have been directed toward establishing an adequate intake of vitamin D throughout the population. National advisory committees in many countries have formulated recommended allowances for the various age groups, public health education programs have stressed the need for the vitamin and the value of sunshine, and the vitamin has been made available to the population at large through provision of inexpensive vitamin supplements and, more recently, the enrichment of milk and a number of commonly used foodstuffs. In consequence, vitamin D deficiency rickets, once a common pediatric problem, is now relatively rare in the United States and other parts of the world.
On the other hand, it has also long been known that vitamin D is potentially dangerous in very high dosage. It had been thought originally that the margin of safety between the requirement of vitamin D and its toxic dosage was very great. However, reports from Great Britain and Switzerland in 1952 drew attention to a group of infants with unexplained hypercalcemia. Additional cases of infantile hypercalcemia began to appear throughout the British Isles, and patients with mild or severe manifestations have been reported in the United States, Canada, and elsewhere. On the basis of circumstantial evidence, vitamin D was implicated in the pathogenesis of the disease, and, as a result, there has been a growing question about the safety of vitamin D intakes which appreciably exceeded the 400 I.U. daily allowance currently recommended for prevention of vitamin D deficiency during growth, pregnancy, and lactation.
- Copyright © 1967 by the American Academy of Pediatrics