Effects of Level and Saturation of Fat and Iron Level and Type in the Diet on Iron Absorption and Utilization by the Rat

Abstract

Two 2 × 2 × 2 factorial studies were done to examine the effects of dietary iron level (10 or 35 ppm), percent dietary fat (5 or 30%) and type of fat (safflower or coconut oil) on heme or nonheme iron absorption and other indices of iron status in rats (liver Fe, Hb, ΔHb). Rats were made moderately anemic (Hb 7.8 ± 0.7 g/dL) by feeding an iron-deficient diet and were then fed one of the 16 experimental diets. Test meals (100 µg Fe) labeled with 59Fe were fed after 5 d and 59Fe absorption determined by whole-body counting. Rats were killed after 5 wk and liver Fe, final Hb and ΔHb were determined. Nonheme iron was better absorbed than heme iron regardless of other dietary factors. Both heme iron absorption and nonheme iron absorption were higher when high (30%) rather than low (5%) dietary fat was fed. The type of fat had no effect. Rats fed both nonheme and heme iron had significantly higher Hb, ΔHb and liver iron when fed coconut oil, compared to safflower oil. Rats fed nonheme iron had higher liver Fe, but not Hb or ΔHb, when fed high rather than low dietary fat. Rats fed heme iron had higher Hb, ΔHb and liver Fe when fed high fat than low fat.