Absorption of iron from recombinant human lactoferrin in young US women.
BACKGROUND
Lactoferrin is a major protein component of human milk, and it binds iron with high affinity. Because the human small intestine has receptors for lactoferrin, a role for it in iron absorption has been suggested.


OBJECTIVE
The objective was to study the absorption of iron from extrinsically labeled purified recombinant human lactoferrin produced in rice and to compare it with the absorption of iron from ferrous sulfate.


METHODS
On 2 occasions 4 wk apart, healthy young women (n = 20) were fed a standardized meal supplemented in randomized order with 59Fe as lactoferrin or as ferrous sulfate. Ten subjects received lactoferrin that had been heat-treated, and 10 subjects received untreated lactoferrin. Iron absorption was measured in a whole-body counter after 14 and 28 d and also was measured by red blood cell incorporation after 28 d.


RESULTS
The difference in whole-body iron absorption between heat-treated (24.6 +/- 20.8%; n = 10) and untreated (16.2 +/- 4.4%; n = 10) lactoferrin was not significant. The difference in whole-body iron absorption between the groups given lactoferrin (20.4 +/- 15.3%; n = 20) or ferrous sulfate (18.8 +/- 13.2%; n = 20) also was not significant. Serum ferritin and iron absorption were inversely correlated in subjects when they received either lactoferrin or ferrous sulfate, which suggested that iron is absorbed from the 2 sources by a similar mechanism.


CONCLUSIONS
Iron is equally well absorbed from lactoferrin (whether heat-treated or untreated) and ferrous sulfate. Thus, iron provided by dietary lactoferrin is likely to be well utilized in human adults.
Department of Nutrition, University of California, Davis, CA 95616, USA. bllonnerdal@ucdavis.edu
Bo
B
Lönnerdal
Annika
A
Bryant
D000328:Adult; D001682:Biological Availability; D018592:Cross-Over Studies; D004912:Erythrocytes / Q000737:chemistry* / Q000378:metabolism; D005260:Female; D005293:Ferritins / Q000097:blood; D005296:Ferrous Compounds / Q000493:pharmacokinetics; D006454:Hemoglobins / Q000032:analysis; D006358:Hot Temperature; D006801:Humans; D007408:Intestinal Absorption; D007504:Iron Radioisotopes; D019266:Iron, Dietary / Q000493:pharmacokinetics*; D007781:Lactoferrin / Q000737:chemistry / Q000493:pharmacokinetics*; D008895:Milk, Human; D012275:Oryza / Q000737:chemistry; D011994:Recombinant Proteins / Q000493:pharmacokinetics
D005296:Ferrous Compounds; D006454:Hemoglobins; D007504:Iron Radioisotopes; D019266:Iron, Dietary; D011994:Recombinant Proteins; C020748:ferrous sulfate; D005293:Ferritins; D007781:Lactoferrin