VITAMIN D NUTRITIONAL STATUS OF PREMATURE INFANTS SUPPLEMENTED WITH 500 IU VITAMIN D2 PER DAY

ABSTRACT. The vitamin D nutritional status of premature infants was assessed by determining plasma 25-hydroxyvitamin D concentrations before and during supplementation with 500 IU vitamin D₂ per day. Fifty-one samples were collected from 25 healthy infants fed breast milk and a vitamin D₃ fortified formula. Gestational age was 32.2±2.4 weeks (mean ± 1 SD). 25-hydroxyvitamin D levels before supplementation correlated well with maternal values ( r =0.81). The infants' mean plasma concentration increased from 30.6±13.7 nmol/l (mean±1 SD) after birth to 46.3±10.5 nmol/l after 9±1 days ( p <0.0025), and to 65.3±16.6 nmol/l after 37±10 days of vitamin D₂ treatment ( p <0.0005). 25-hydroxyvitamin D₂ and 25-hydroxyvitamin D₃ were determined separately, and it appeared that the rise was accounted for by the D₂ fraction while 25-hydroxyvitamin D₃ concentrations were unchanged. The results demonstrate that vitamin D₂ is well absorbed and hydroxylated in the 25 position by premature infants free of associated disease, and that a supplementation of 500 IU per day in addition to breast milk and a regular vitamin D fortified formula is adequate to rapidly establish 25-hydroxyvitamin D levels within the normal adult range.