Absorption of dietary iron and ferrous ascorbate by infants - abstract

ABSTRACT

There is no substantial evidence in adults that only a small proportion of the iron, chemically measured, in various foodstuffs is available for absorption. Hussain et al showed that only about 4.5 per cent of the iron present in wheat is absorbed by a normal adult whereas 12 per cent of the iron in ingested blood is absorbed. Even in the presence of iron deficiency the absorption of iron from carbohydrate foods is only marginally improved. In adults the iron absorbed from cooked soybean meal has been found to be better than that from any other vegetable source, and as the iron content of this food stuff is relatively high, it could be a useful source of iron for the infant. Absorption tests were carried out in 'normal' infants and treated malnourished infants, 9 months to 15 months old, using a whole body radioactivity counter and feeding corn or soybean meal which had radioactive iron (Fe59) incorporated into the plants during cultivation. The meals were arranged to contain 0.5 mg of iron and radioactivity remaining in the body at 7 days was used to calculate the percentage of iron absorbed. Test were repeated in the fasting subjects using ferrous sulphate and ascorbic acid mixture (ferrous ascorbate) at a dose level of 0.5 mg of iron per test. Only small amounts of radioactivity were administered, in the order of 0.1 æCi and the efficiency of the counter was such that at the 5 per cent absorption level, this could be measured with an accuracy of plus or minus 2.5 per cent of this figure. Cornmeal was given to 15 infants and an average absorption of 3 per cent of the iron was recorded compared to 24 per cent for ferrous ascorbate. In the first study in 10 infants given soybean meal, the mean absorption was 2.8 per cent but in this group the soybean meal was simply boiled and given as a porridge. In a further 9 infants the soybean porridge was baked at 300 degree F as a cake and then broken up and administered mixed with water. In this series the average absorption was 8 per cent which is more in keeping with the reported results in adults. In a further 6 infants the mean absorption of labelled haemoglobin iron was 14.4 per cent. During the course of the study it was noted that a pyrexia at the time of the absorption test was associated with a very low absorption of iron both from food and from ferrous ascorbate. Absorption measured in the same infant before or after the pyrexia was at expected levels for the iron status. Absorption was related to the haemoglobin P.C.V. and serum iron and tranferrin levels in all these infants. Iron absorption was usually but not always higher in those infants who were judged to be iron deficient(AU)