Evaluation of iron bioavailability in infant weaning foods fortified with haem concentrate

Nutritional iron deficiency in infants over 4 months of age is one of the most common deficiency disorders. Dietary iron is comprised of non-haem and haem iron, the latter being absorbed by a separate pathway and more efficiently than non-haem iron. Fortification of infant weaning foods is one of the strategies adopted for preventing iron deficiency and the aim of this project was to examine the potential use of haem iron concentrate as a fortificant.

Sixteen non-anaemic 6-month old infants were recruited and allocated to two groups of 8. Each infant consumed 2 meals/day of a commercial weaning food (100 g) for 7 consecutive days containing 40 mg ascorbic acid and 2.5 mg haem iron/100 g (Group 1) or the same quantity of iron as ferrous sulphate plus 40 mg ascorbic acid (Group 2). Bioavailability was assessed by chemical balance using carmine to mark the beginning and end of the faecal collection. The effect of haem iron concentrate (as a candidate for the factor in meat that enhances iron absorption) was examined by measuring its effect on 57Fe-labelled non-haem iron absorption.

There was no difference in iron balance between the two groups. Mean iron retention was 3.5 (SD 2.1) mg/day in Group 1 (haem iron) and 3.0 (SD 2.4) mg/day in Group 2 (ferrous sulphate). Haem concentrate did not enhance the absorption of 57Fe-labelled non-haem iron, Group 1: 1710 (SD 11.1)%, Group 2: 28.4 (SD 17.7)%.

Haem iron concentrate appears to be a highly bioavailable form of iron when added to infant weaning foods. This protein is not, however, responsible for the enhancing effect of animal protein on non-haem iron absorption.