Abstract

Pediatric Research (1984) 18, 197A–197A; doi:10.1203/00006450-198404001-00623

THE EFFECTS OF MATERNAL ULTRAVIOLET-B IRRADIATION ON VITAMIN D CONTENT OF HUMAN MILK

Frank R Greer1, Bruce W Hollis1 and Reqinald C Tsang1

1Univ. of Wisconsin, Madison, WI; Case Western Reserve Univ., Cleveland, OH; Univ. of Cincinnati, Cincinnati, OH.

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Abstract

We studied the effects of a known amount of total-body ultra-violet-B light irradiation (1.5 M.E.D. equivalent to 30′ of sunshine at noon on a clear summer day in fair-skinned women) on both serum and breast milk concentrations of vit D3, vit D2, 25-OH vit D3, 25-OH vit D2 and 1,25(OH)2 vit D in 5 lactating Caucasian women. By 48 hrs post UV-E exposure, serum vit D3 increased from 1.0±0.2 (SEM) ng/ml to 22.9±5.4 ng/ml (p<0.01, paired t test), remaining increased up to 14 days (2.30±0.12 ng/ml, p<0.01). Simultaneously, breast milk vit D3 rose from 6 to 71 IU/L (p<0.02, range 34-148 IU/L) within 48 hr. of irradiation, remaining elevated up to 14 days (12 IU/L, p<0.05). Breast milk vit D3 correlated with serum vit D3 (r=0.91). 48 hrs post irradiation serum 25-OH vit D3 increased from 13.9±2.7 to 17.6±3.3 ng/ml (p< 0.05), peaking at 7 days (20.5±3.0 ng/ml, p<0.02) and remaining elevated at 14 days (20.3±3.2 ng/ml, p<0.05). There was no change in 25-OH vit D3 in breast milk post irradiation. There was no change in serum or milk vit D2, 25-OH vit D2, or 1,25(OH)2 vit D following irradiation. There was no correlation between breast milk fat (mean 3.4±2.4 [SD] g/dl) and milk vit D3 or its metabolites. We conclude that maternal UVB irradiation (and thus sunshine exposure) significantly increases vit D3 in human milk. Despite a rise in serum 25-OH vit D3, vit D3 is the only vitamin form which is readily transferred into human milk from maternal serum following maternal irradiation.