Endocrine Abstracts

The prevalence of vitamin D deficiency in at-risk groups is rising even in sunny countries. Aim of this study was to compare vitamin D status and effect of vitamin D supplementation of moderate risk (mildly pigmented, WHO skin type 2) breastfed newborns from sunny and temperate climate zones. Newborns in Perth (30°S, group 1:5 male, 6 female) did not receive any vitamin D supplementation, newborns in Berlin (52.5°N, 17 male, 23 female) were randomised into n=20 on 250 units (group 2) and n=20 on 500 units (group 3) of vitamin D3 per day.

We compared serum 25 OH vitamin D (25OHD), alkaline phosphatase, albumin; serum and urine calcium, phosphate and creatinine; sun exposure in hours/day and UVB exposure (minimal erythema dose, MED). Measures were obtained on day 5 and 6-8 weeks after delivery. UVB exposure was continuously quantified by spectral analysis using bio-weighted dosimeters. Surrounding factors and nutrition were assessed by questionnaires and analysis of meteorological data.

25OHD levels did not vary significantly between groups on day 5 (nmol/L±S.E.M., groups1/2/3): 49.2±7.7/68.9±8.1/64.1±5.8; 6–8 weeks later only newborns in Perth presented with subclinical vitamin D deficiency: 45.9±14; group2:128.8±10.6, group3:151.1±18.3, P<0.05. Sun exposure time (h/day±S.E.M.) was significantly lower in Perth: 0.5±0.08/2.14±0.13/1.7±0.3, P<0.05. Dosimetry revealed similar UVB exposure (MED/day±S.E.M.) for all groups: 0.03±0.02/0.04±0.02/0.03±0.02. The remaining parameters were normal in all participants.

Newborns in Perth did not achieve sufficient 25OHD levels despite living in a sunny climate. To improve vitamin D photobiosynthesis their sun exposure can be optimised without increasing the risk of skin cancer; otherwise vitamin D supplementation is needed. In Berlin, Germany, 250 units of vitamin D3 per day resulted in sufficient vitamin D supply.