Bioavailability to rats of iron in six varieties of wheat grain intrinsically labeled with radioiron.

Bioavailability to anemic rats of iron in six varieties of wheat grain was assessed by a whole-body radioassay procedure. Intrinsically labeled kernels were harvested from plants grown in 59Fe-labeled nutrient solutions. The varieties used were selected from 18 varieties of field-grown wheat grain that were analyzed for iron, protein and phytate content. Concentrations of iron, phytate and protein in grain of field-grown varieties ranged from 34 to 55 ppm, 0.7 to 1.2% dry wt and 11.3 to 15.4% dry wt, respectively. In grain from varieties grown in nutrient solutions, iron, phytate and protein concentrations ranged from 35 to 50 ppm, 1 to 1.2% dry wt, and 13.8 to 16.8% dry wt, respectively. Depending on the variety of intrinsically labeled grain fed in test meals to anemic rats (hemoglobin averaged 5.8 g/dL), absorption of 59Fe ranged from about 62 to 74% of the dose; differences among varieties were not significant (P greater than 0.05). Rats fed 59Fe-labeled FeCl3 absorbed about 71% of the dose, which was similar to the average amount (69% of dose) absorbed by rats fed wheat. We concluded that selection of wheat varieties for increased yield or protein content has not adversely affected the bioavailability of iron in the grain.