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United States Department of Agriculture

Agricultural Research Service

Research Project: ABSORPTION AND METABOLISM OF ESSENTIAL MINERAL NUTRIENTS IN CHILDREN Title: Alpha-lactalbumin and casein-glycomacropeptide do not affect iron absorption from formula in healthy term infants

Authors
item Szymlek-Gay, Ewa -
item Lonnerdal, Bo -
item Abrams, Steven -
item Kvistgaard, Anne -
item Domellof, Magnus -
item Hernell, Olle -

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 2, 2012
Publication Date: July 1, 2012
Citation: Szymlek-Gay, E.A., Lonnerdal, B., Abrams, S.A., Kvistgaard, A.S., Domellof, M., Hernell, O. 2012. Alpha-lactalbumin and casein-glycomacropeptide do not affect iron absorption from formula in healthy term infants. Journal of Nutrition. 142(7):1226-1231.

Interpretive Summary: The iron contained in infant formulas is not absorbed very well. It was thought that some proteins found more in human milk than in infant formulas might increase the amount of iron that was absorbed from the formulas if added to them. So, we tested adding two proteins, called alpha-lactalbumin and casein-glycomacropeptide to a formula. When tested using stable isotopes we did not find any affect of adding these to the formulas.

Technical Abstract: Iron absorption from infant formula is relatively low. Alpha-lactalbumin and casein-glycomacropeptide have been suggested to enhance mineral absorption. We therefore assessed the effect of alpha-lactalbumin and casein-glycomacropeptide on iron absorption from infant formula in healthy term infants. Thirty-one infants were randomly assigned to receive 1 of 3 formulas (4 mg iron/L, 13.1 g protein/L) from 4-8 wk to 6 mo of age: commercially available whey-predominant standard infant formula (standard formula), alpha-lactalbumin-enriched infant formula (alpha-LAC), or alpha-lactalbumin-enriched/casein-glycomacropeptide-reduced infant formula (alpha-LAC/RGMP). Nine breast-fed infants served as a reference. At 5.5 mo of age, (58)Fe was administered to all infants in a meal. Blood samples were collected 14 d later for iron absorption and iron status indices. Iron deficiency was defined as depleted iron stores, iron-deficient erythropoiesis, or iron deficiency anemia. Iron absorption (mean +/- SD) was 10.3 +/- 7.0% from standard formula, 8.6 +/- 3.8% from alpha-LAC, 9.2 +/- 6.5% from alpha-LAC/RGMP, and 12.9 +/- 6.5% from breast milk, with no difference between the formula groups (P = 0.79) or all groups (P = 0.44). In the formula-fed infants only, iron absorption was negatively correlated with serum ferritin (r = -0.49; P = 0.005) and was higher (P = 0.023) in iron-deficient infants (16.4 +/- 12.4%) compared with those with adequate iron status (8.6 +/- 4.4%). Our findings indicate that alpha-lactalbumin and casein-glycomacropeptide do not affect iron absorption from infant formula in infants. Low serum ferritin concentrations are correlated with increased iron absorption from infant formula.

Last Modified: 10/23/2014
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