Calculating dietary iron bioavailability: refinement and computerization.

Previous laboratory studies have shown that dietary iron during digestion forms two pools: heme and nonheme. Even though human beings absorb heme iron at a higher rate than nonheme iron, the major portion of food iron is nonheme (all grain and vegetable iron plus approximately 60 percent of the iron in meat, fish, and poultry). The absorption rate of nonheme iron can be increased markedly by concomitant consumption of ascorbic acid and/or meat/fish/poultry. These concepts have been incorporated into a model for estimating the quantity of bioavailable iron, the first trace mineral to be thus considered. This model has now been revised for easier and more refined application.