BONE-MINERAL CONTENT IS NOT REDUCED DESPITE LOW VITAMIN-D STATUS IN BREAST MILK-FED INFANTS VERSUS COWS MILK-BASED FORMULA-FED INFANTS

The effect of low or borderline vitamin D status on bone mineralizatio n of exclusively breast milk-fed infants has not been studied. The low vitamin D status of Korean breast milk-fed infants may theoretically have adverse effects on bone mineralization. Assuming that bone minera l content (BMC) relates in part to vitamin D status, we hypothesized t hat serum 25-hydroxyvitamin D (25-OHD) concentration and BMC would be low, and serum osteocalcin concentration high, reflecting active bone turnover, in breast milk- versus formula-fed infants born in the winte r. Eighteen breast milk- and 17 formula-fed infants were recruited at ages 2 to 5 months. The BMC of the lumbar(1-4) spine region was measur ed by using dual energy x-ray absorptiometry. The BMC and serum osteoc alcin levels were similar for both groups. The serum 25-OHD level was significantly lower in breast milk- than formula-fed infants; 44% of t he breast milk group versus 6% of the formula group had serum 25-OHD l evels less than 28 nmol/L (11 ng/ml), the lower limit of normal. The B MC did not correlate with the serum 25-OHD level. Thus BMC and serum o steocalcin levels in 2- to 5-month-old infants were not different by t ype of feeding, despite low vitamin D status in breast milk-fed infant s. We speculate that adequate mineral absorption occurs during this pe riod from a predominantly (vitamin D independent) passive transport me chanism.