Effect of soya-bean protein on meat iron solubility and absorption in rats.

1. Soya-bean proteins were used to replace 30 and 50% of the protein from 59Fe-labelled pigeon (Columba L.) and chicken meat, and the solubility of the meat 59Fe in vitro and its absorption in vivo in rats in the presence and absence of soya-bean proteins were measured. 2. Replacement of part of the chicken meat by soya-bean proteins reduced 59Fe solubility from chicken meat at all stages during simulated in vitro digestion. 3. 59Fe absorption from 59Fe-labelled chicken meat when given to both Fe-replete and Fe-deficient rats was reduced in the presence of soya-bean proteins but was unaffected by the presence of casein or bovine serum albumin. 59Fe-absorption from pigeon meat in the presence of soya-bean proteins was not reduced to the same extent as that from chicken meat. 4. There was no significant effect of soya-bean proteins on 59Fe-labelled haemoglobin Fe absorption in vivo in Fe-replete rats. 5. Absorption of 59Fe from the isolated haemoproteins from chicken meat was unaffected by soya-bean proteins but 59Fe absorption from the main non-haem-Fe fractions was strongly inhibited, particularly from haemosiderin.