Does Human Lactoferrin in the Milk of Transgenic Mice Deliver Iron to Suckling Neonates?
Lactoferrin is an iron-binding glycoprotein abundantly present in human milk, and has been postulated both to increase and to decrease intestinal iron absorption. To examine this problem, the interaction of milk iron with pup hemoglobin was studied in controls and in transgenic mice overexpressing human lactoferrin in their milk (2 lines expressing 12 mg/mL and 4 mg/mL, respectively). At day 14 of gestation, pregnant mice were switched from a diet of commercial chow containing iron at 300mg/kg to diets containing 5, 15, or 50 mg iron/kg; controls continued on chow. Nontransgenic pups were cross-fostered to transgenic dams to ensure that any results found in the pups were the effect of milk components. The hemoglobin level in the blood of 10-day-old suckling neonates was measured and calculated as total hemoglobin per pup. The total hemoglobin levels were lower in the pups receiving milk high in human lactoferrin, but the difference reached significance (P < 0.02) only at the highest level of dietary iron. Our findings do not support the hypothesis that lactoferrin functions as an intestinal iron scavenger, at least at high doses.
KeywordsHuman Milk Iron Status Intestinal Brush Border Human Lactoferrin Bovine Lactoferrin
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- Casey CE, Smith A, Zhang P. Macrominerals in human and animal milks. In: Jensen RE, editor. Handbook of Milk Composition. San Diego: Academic Press; 1995. pp 87–98.Google Scholar
- Davidson LA, Lonnerdal B. Lactoferrin and secretory IgA in the feces of exclusively breast-fed infants. Am J Clin Nutr 1987;41:852–861.Google Scholar
- Davidson LA, Lonnerdal B. Fe-saturation and proteolysis of human lactoferrin: effect on brush-border receptor-mediated uptake of Fe and Mn. Am J Physiol 1989;257:G390–G394.Google Scholar
- Ellison RT. The effects of lactoferrin on gram-negative bacteria. Adv Exp Med Biol 1994;357:71–90. Fransson GB, Lonnerdal B. Iron in human milk J Pediatr 1980;96:380–384.Google Scholar
- Iyer S, Lonnerdal B. Lactoferrin, lactoferrin receptors and iron metabolism. Eur J Clin Nutr 1993; 47:232–241.Google Scholar
- Lonnerdal B. Iron in breast milk. In: Stekel A, editor. Iron Nutrition in Infancy and Childhood. Volume 4, Nestlé Nutrition Workshop Series. New York: Raven Press; 1984. pp. 95–118.Google Scholar
- Neville MC, Chatfield K, Hanson L, Lewis A, Monks J, Nuijens J, 011ivier-Bousquet M, Schanbacher F, Sawicki V, Zhang P. Lactoferrin secretion into mouse milk. Development of secretory activity, the localization of lactoferrin in the secretory pathway, and interactions of lactoferrin with milk iron. Adv Exp Med Biol 1998;443:141–153.PubMedGoogle Scholar
- Slimes MA, Vuori E, Kuitunen P. Breast milk iron: a declining concentration during the course of lactation. Acta Paediatr Scand 1979;68:29–31.Google Scholar