Iron fortification of infant milk formula: the effect on iron status and immune function.
We conducted a randomized double-blind trial of a cow's milk infant formula with increased iron fortification in order to confirm its safety and to measure its effects on iron status and immune function. A group of full-term, well nourished and healthy infants was followed from the age of 3 months to 1 year. A control group of 74 infants was given a commercially available infant formula containing 8.3 mg Fe/100g. The test group of 75 infants received a similar formula with 40 mg Fe/100 g. The formula with the extra iron proved to be safe and, when compared with the control group, the children in the test group had significantly improved iron status as reflected by the proportion of children classed as normal (25 of 61 cf. 44 of 65; p less than 0.003), and by the mean values of the haemoglobin concentration (11.5 cf. 11.9 g/dl; p = 0.04), red cell distribution width (15.5% cf. 14.4%; p = 0.0005), red cell zinc protoporphyrin (3.4 cf. 4.0 micrograms/g Hb; p = 0.04) and ferritin (29 cf. 17.3 micrograms/l; p = 0.004). The extra iron fortification depressed zinc concentration in plasma (90.6 cf. 83.5 micrograms/l; p = 0.05). There was no significant difference between the two groups for laboratory measures of immune function or for incidence of infection. No adverse effects such as infection could be attributed to the increased iron. We conclude that iron fortification of cow's milk infant formula may be safely increased to 40 mg/100 g (i.e. by a factor of 4.8 over the common concentration of 8.3 mg/100 g), but that this has less than the expected effect on iron status. Further studies are required to define (a) the long-term role of facilitators of iron absorption such as ascorbic acid, (b) the interaction of iron with absorption of divalent trace elements such as zinc, and (c) the effect of iron status on immune function and susceptibility to infection.
Power
H M
HM
Department of Paediatrics and Child Health, University of Cape Town, South Africa.
Heese
H D
HD
Beatty
D W
DW
Hughes
J
J
Dempster
W S
WS
D000747:Anemia, Hypochromic / Q000517:prevention & control; D004311:Double-Blind Method; D004909:Erythrocyte Indices; D005293:Ferritins / Q000097:blood; D005527:Food, Fortified; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007109:Immunity / Q000187:drug effects; D007223:Infant; D007225:Infant Food; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D011524:Protoporphyrins / Q000097:blood
D006454:Hemoglobins; D011524:Protoporphyrins; D005293:Ferritins; D007501:Iron