Meat enhances nonheme iron absorption in pigs

Abstract

Human subjects absorb heme iron (Fe) more efficiently than nonheme Fe under most conditions. Meat enhances nonheme Fe absorption from most diets. It is not known whether these effects also occur in the pig, a promising model for human Fe absorption studies. The objective of this study was to compare Fe bioavailability from diets containing nonheme Fe (NHI), nonheme Fe with meat (NHI/M) and heme Fe (HI) in the weanling pig. Iron bioavailability was measured by hemoglobin (Hb) repletion assay. Diets were formulated to contain 150 mg Fe/kg diet. Nonheme Fe was supplied as ferric citrate and heme Fe as dried animal red blood cells. Pigs were made anemic by reducing the standard Fe injection at birth to 30 mg and feeding a low Fe transition diet post-weaning until age 41 days. At 41 days of age, pigs were assigned to 3 groups of 8 animals such that mean Hb concentration and body weight of each group were nearly equal. Groups were randomly assigned to 1 of 3 repletion diets. After 7 days feeding, Hb repletion efficiency (HRE) was 21.8% in pigs fed the NHI/M diet compared to 11.2% and 9.1% in pigs fed the NHI or HI diets, respectively. The results presented here demonstrate that, in Fe-deficient weanling pigs, meat increases nonheme Fe bioavailability from corn-based diets while heme Fe, supplied by dried animal red blood cells, is no more bioavailable than Fe from ferric citrate. The results of this study provide further evidence of the validity of the pig model for studying food Fe bioavailability.