IRON-ABSORPTION FROM THE WHOLE DIET - COMPARISON OF THE EFFECT OF 2 DIFFERENT DISTRIBUTIONS OF DAILY CALCIUM INTAKE

The possibility of reducing calcium inhibition of iron absorption by d ecreasing calcium intake in lunch and dinner meals, which provided the most dietary iron, was examined in 21 healthy female volunteers. Duri ng a 10-d period, nonheme iron in all meals was extrinsically labeled with radioisotopic iron to a uniform specific activity. Iron absorptio n from two identical 10-d periods was compared when meals were labeled with two different iron radioisotopes and when the same amount of cal cium (937 mg) was distributed in two ways, in either mainly breakfast and late evening meals or more evenly in all meals. About 30-50% more iron was absorbed when no milk or cheese was served with lunch or dinn er. The difference was statistically significant. Median iron requirem ents (1.61 mg/d) calculated from body weight and menstrual iron losses agreed with the mean value of median iron absorption in the two 10-d periods (1.54 mg/d), which supports the validity of the present method . A reasonable separation of calcium and iron intakes would improve ir on nutrition.