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Seasonal vitamin D in African American and white infants

UCMC-PEDS PO Box 670541 Cincinnati, OH 45267–0541

Dear Sir:

Thank you for publishing the article on seasonal vitamin D in 51 black and 39 white individuals by Harris and Dawson-Hughes (1) and the accompanying editorial by Norman (2). In a 1986 study in 198 subjects < 18 mo of age, we found that differences in vitamin D status by race were significant in winter but not in summer (3). What was also surprising was that African American infants had significantly higher 1,25-dihydroxyvitamin D concentrations than white infants, both in winter and in summer. The study was uniformly blocked by sex, race, age, season, and diet (formula-fed compared with breast-fed infants). We advanced the thesis (4) that the renal 1-hydroxylase enzyme is particularly active in infancy as an adaptive mechanism in conditions in which serum 25-hydroxyvitamin D concentrations are low, such as during the winter. High 1,25-dihydroxyvitamin D concentrations coincide with periods when serum phosphate concentrations are significantly lower [in winter and in African American infants (3)], which could serve as the stimulus for 1,25-dihydroxyvitamin D production during these periods. What may be little known is that in human milk-fed infants who do not receive vitamin D supplementation (5), there can be a marked 2- to 3-fold seasonal alteration in serum 25-hydroxyvitamin D concentrations.

Thus, in infancy there are 1) marked seasonal variations in vitamin D status, 2) marked differences in vitamin D status by race (African Americans compared with whites), and 3) higher serum 1,25-dihydroxyvitamin D concentrations in the winter than in other seasons and in African Americans than in whites. These findings provide an additional perspective on the issue of seasonal variations in vitamin D status.

REFERENCES

1. Harris SS, Dawson-Hughes B. Seasonal changes in plasma 25-hydroxyvitamin D concentrations of young American black and white women. Am J Clin Nutr 1998;67:1232–6.[Abstract]
2. Norman AW. Sunlight, season, skin pigmentation, vitamin D, and 25-hydroxyvitamin D: integral components of the vitamin D endocrine system. Am J Clin Nutr 1998;67:1108–10.[Medline]
3. Lichtenstein P, Specker B, Tsang RC, Mimouni F, Gormley C. Calcium-regulating hormones and minerals from birth to 18 months of age: a cross-sectional study. I. Effects of sex, race, age, season, and diet on vitamin D status. Pediatrics 1986;77:883–90.[Abstract/Free Full Text]
4. Specker BL, Tsang RC. Cyclical serum 25-hydroxyvitamin D concentrations paralleling sunshine exposure in exclusively breast-fed infants. J Pediatr 1987;110:744–7.[Medline]
5. Tsang RC, Cruz M, Specker B. Vitamin D in infancy: 25-hydroxyvitamin D, an important bioactive principle in vivo in infancy? In: Norman AW, Bouillon R, Thomasset M, eds. Vitamin D: gene regulation structure function analysis and clinical application. Berlin: W De Gruyter, 1991.

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Tsang, R. C Search for Related Content PubMed PubMed Citation Articles by Tsang, R. C Agricola Articles by Tsang, R. C