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Few subjects have evoked as much interest in the past five to 10 years as vitamin D. Whereas the primary objective a few years ago was the prevention of rickets, the presence of vitamin D receptors in most cells of the body along with evidence that vitamin D has a role in the prevention and modification of disease has led to a re-examination of what defines optimal plasma 25-hydroxyvitamin D status (1). Using these much higher levels to define adequate vitamin D status means that the prevalence of vitamin D deficiency is much higher than previously believed.
Roth (2), in the present issue of Paediatrics & Child Health, gives advice to parents regarding vitamin D that may be misleading and premature. It is true that present evidence suggests that rickets can be prevented in the first year of life by a total of 400 IU/day of vitamin D from all sources. However, this ignores the increasing awareness of the importance of adequate vitamin D levels in the prevention of other vitamin D-associated conditions. Furthermore, grades of Levels of Evidence of the references he cites in Part A are not provided.
Nor does he stress the importance of an adequate maternal vitamin D status during pregnancy for the developing fetus and newborn, a subject that has been associated with many good studies. He also suggests that vitamin D supplementation beyond infancy is not necessary if toddlers are drinking at least two cups of milk each day. Many toddlers do not drink that much milk and are at risk of deficiency. We should remember the Manitoba experience with vitamin D deficiency in First Nations groups (3,4). Also, the Canadian Paediatric Society (CPS) document titled “Sun Safety”, his reference 16, does not conflict with the CPS recommendation of sun exposure.
Roth bases his suggestions regarding vitamin D supplementation on the positions of the Institute of Medicine and Health Canada, which have not been consistent. In 1998 and again in September 2009 (5), the Office of Dietary Supplements, National Institutes of Health suggested that a total intake of 5 μg (200 IU)/day for children from birth to 13 years was adequate. In 1998, Health Canada was in agreement, but in 2004, the recommendation was empirically changed to 400 IU/day (6).
Unfortunately, rickets continues to be a problem in Canada, with 104 confirmed cases in Canada from July 2002 to July 2004 (7), with a predominance among breastfed infants and dark-skinned individuals living in the north, in spite of CPS recommendations regarding supplementation. Furthermore, studies of northern Canadians have consistently shown a high prevalence of vitamin D insufficiency and deficiency.
The 2007 CPS position statement “Vitamin D supplementation: Recommendations for Canadian mothers and infants” included recommendations based on the best available evidence at the time and is still timely. The field was thoroughly researched and the paper was reviewed by many paediatric and nutritional experts. Since then, there have been no studies suggesting a change in approach.
With regard to advice to mothers, there is no reason to change the recommendation of infant vitamin D intake of 400 IU/day during the first year of life, increasing it to 800 IU/day between October and April. This recommendation was originally suggested in the CPS statement of 2002, and there have been no reported problems with this dose.
Two events may modify our position. The first is a McGill University double-blind vitamin D dose-response study (8) in infants currently getting under way. Unfortunately all of the subjects proposed will come from the Montreal, Quebec, area. There is a need for a similar study in a region much further north. The second is the report of the expert committee of the Institute of Medicine due in May 2010. This report will focus on the effect of vitamin D intake on circulating 25-hydroxyvitamin D and health outcomes, and the levels of intake associated with adverse effects. Meanwhile, there is no reason to modify recommendations in the CPS position statement.