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Title: Fractional calcium absorption is similar in premature infants fed human milk fortified with a human milk or bovine milk-based fortifier

Author
item ROGERS, STEFANIE - BAYLOR COLLEGE MED
item HICKS, PENNI - BAYLOR COLLEGE MED
item HAWTHORNE, KELI - BAYLOR COLLEGE MED
item Abrams, Steven

Submitted to: Pediatric Academic Society
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/2008
Publication Date: 5/5/2008
Citation: Rogers, S.P., Hicks, P.D., Hawthorne, K.M., Abrams, S.A. 2008. Fractional calcium absorption is similar in premature infants fed human milk fortified with a human milk or bovine milk-based fortifier [abstract]. Electronic-Pediatric Academic Societies. Abstract No. 5840.9. Available: http://www.abstracts2view.com/pas/view.php?nu=PAS08L1_339.

Interpretive Summary:

Technical Abstract: Preterm infants require fortification of human milk (HM) to provide adequate calcium for bone mineralization. A HM-based fortifier has recently been introduced. However, the bioavailability of the calcium in this product and the ability of a HM-based fortifier to meet preterm infants mineral needs are unknown. We sought to evaluate calcium metabolism in infants fed fortified HM. We hypothesized that fractional calcium (Ca) absorption (abs) would be equivalent in preterm infants fed a donor HM-based fortifier (DonF) compared with a bovine milk-based fortifier (BovF). Groups of HM-fed preterm infants < 32 wks gestation were sequentially studied using DonF or BovF. Ca abs was also compared to historical controls (HIST) fed a different bovine-based fortifier. Duration of study was 6 weeks, with Ca-abs assessed at week 2 using a stable isotope technique. All data expressed as mean +/- SD. The patients were similar in both groups, with DonF babies (n=10) measuring 1154 +/- 270 g and 29 +/- 1 weeks at birth, and the BovF group (n=8) measuring 1113 +/- 288 g (p=0.2) and 28 +/- 2 weeks (p=0.8) at birth. Fractional Ca was the same in both groups (Don F 44.2 +/- 17.3% vs. 50.5 +/- 19.8% in BovF, p=0.47), but the Ca intake was less in DonF (160 +/- 26 mg/kg/day vs. 223 +/- 14 mg/kg/day in BovF, p<0.001). However, the infants had less total Ca absorption in DonF (71 +/- 29 mg/kg/day vs. 113 +/- 46 mg/kg/day in BovF, p=0.03) and less total Ca retention in Don F (59 +/- 29 mg/kg/day vs. 101 +/- 47 mg/kg/day in BovF, p=0.03). Growth was similar in DonF fed infants with weight gain of 21.9 +/- 5.6 g/day, linear growth of 1.1 +/- 0.4 cm/wk, and head growth of 1.0 +/- 0.1 cm/wk and BovF fed infants weight gain of 24.8 +/- 3.3 g/day (p=0.2), linear growth of 1.1 +/- 0.4 cm/wk (p=0.9), and head growth of 1.0 +/- 0.1 cm/wk (p=0.7). There were no differences in markers of bone mineral status (Initial SOS U/S, decrease in SOS U/S over study period, Fat Free Mass as measured in body composition analyzer, and Avg Alkaline Phosphatase). HIST infants were BW 970 +/- 40 g, and 28 +/- 1 wk gestation at birth. Abs data was similar to BovF (Fract Ca Abs 52 +/- 13.3% (p=0.26); Ca Intake 178 +/- 11 mg/kg/day (p=0.05); Total Ca Abs 92 +/- 24 mg/kg/day (p=0.09)). Fractional Ca-abs was similar among fortifiers. Due to a lower Ca intake, total Ca-abs was lower in DonF than BovF. Estimated Ca retention did not reach in-utero accretion rates in DonF. No differences in growth or markers of bone health were noted. These data demonstrate good bioavailability of Ca from a HM-based fortifier but lower than in utero retention due to relatively lower mineral concentration. Physiological outcomes may not depend on achieving in utero retention, but long-term data would be needed to assess this.