Self-controlled study on the effect of vitamin D supplementation on serum 25-hydroxyvitamin D level of breast-fed infants in winter / 中华临床营养杂志

ABSTRACT

Objective To identify the effect of oral cod liver oil on serum 25-Hydroxyvitamin D [25 (OH)D] level in breast-fed infants during winter.Methods Healthy newborn infants were recruited at Children's Hospital Affiliated to Capital Institute of Pediatrics between December 2009 and February 2010 for the self-controlled study.Serum samples were obtained with 2 ml umbilical cord blood for each neonate.The neonates received vitamin D supplementation in the form of oral cod liver oil from 15 days to 4 months after birth.For each exclusively breastfed infant,2 ml fasting venous blood was collected at the end of postnatal 4 months to separate serum.Serum 25 (OH) D concentrations of the infants were determined with umbilical cord blood serum and venous blood serum.Results Altogether 43 exclusively breastfed infants were enrolled,including 26 boys and 17 girls.The mean serum 25 (OH)D concentration in umbilical cord blood was (20.9 ± 5.1) nmol/L (12.5-32.1 nmol/L).All the neonates were vitamin D deficient.The mean serum 25 (OH) D concentration in infants at 4 months was (106.3 ± 42.4) nmol/L (30.2-208.5 nmol/L).Among the infants,the serum 25 (OH) D level was ＜ 50 nmol/L in 4 infants (the rate of vitamin D deficiency being 9.3％),50-75 nmol/L in 7,75-150 nmol/L in 25,and ≥150 nmol/L in 7.A positive correlation was detected between serum 25(OH)D level and cod liver oil dose (r =0.530,P =0.001).The average percentage of the missed doses (missed doses/prescribed doses) was 36.1％,negatively correlated with serum 25 (OH)D level (r =-0.634,P =0.001).Conclusions Vitamin D deficiency is common among infants born during winter in northern China.Daily oral intake of cod liver oil in infants can significantly increase serum 25 (OH) D level; However,the prevention of vitamin D deficiency cannot be ensured if doses are missed.