Duration of the inhibitory effect of calcium on non-haem iron absorption in man.

We investigated the duration of the inhibitory effect of calcium from milk and cheese (340 mg) in a breakfast meal on non-haem iron absorption from a hamburger meal eaten 2 or 4 h after the breakfast. The effect of calcium on iron absorption was studied in 21 human subjects by using paired observations and a dual-radioisotope method (55Fe and 59Fe). No duration effect of calcium on iron absorption was observed in this study.

Bioavailability in man of iron in human milk and cow's milk in relation to their calcium contents.

Iron absorption from human milk and cow's milk was compared in the same subjects using two radio-iron tracers and extrinsic labeling of the iron. Previously observed higher iron absorption from human milk was confirmed as 19.5 +/- 17.

Calcium and iron absorption: mechanism of action and nutritional importance.

We investigated the inhibitory effect of calcium on iron absorption in 57 human subjects. Three studies suggested that the effect is not located in the gastrointestinal tract. The presence of phytate in a meal and formation of calcium-iron-phytate complexes is not a prerequisite for the inhibition.

Iron absorption from bread in humans: inhibiting effects of cereal fiber, phytate and inositol phosphates with different numbers of phosphate groups.

Iron absorption was measured from five kinds of bread made from various types of flour and fermented in different ways in order to obtain a wide variation in the content of fiber, phytate (inositol hexaphosphate) and its degradation products, inorganic phosphate and inositol phosphates with fewer numbers of phosphate groups (inositol pentaphosphate through monophosphate). Each experiment had 9-10 subjects and, in each subject, iron absorption was measured from control rolls made from low extraction wheat flour and one kind of test roll using two different radioiron tracers: 55Fe and 59Fe. The inhibition of iron absorption was closely related to the content of phytate-phosphorous as determined using the AOAC method, and to the sum of the tri- through hexaphosphate groups as determined using the HPLC method.

Iron requirements in menstruating women.

Total-absorbed-iron requirements in adult and teen-age menstruating women were calculated from previously published data on menstrual blood losses; hemoglobin distribution in healthy, nonanemic women; basal iron losses; and growth requirements in teen-agers. Because present calculations included the effect of the variation of all indices, the new requirements for iron were increased to 2.84 mg/d in adult women and 3.

Competitive inhibition of iron absorption by manganese and zinc in humans.

Zinc and manganese may interfere with iron absorption because of similar physicochemical properties and shared absorptive pathways. The effects of zinc and manganese on iron absorption were studied in human subjects by using paired observations and a dual-radioisotope method (55Fe and 49Fe). Manganese inhibited iron absorption both in solutions and in a hamburger meal.

Dose-dependent inhibitory effect of phenolic compounds in foods on nonheme-iron absorption in men.

Nonheme-iron absorption from a typical Southeast Asian meal was studied to examine the effect of a common vegetable, Yod Kratin, which contains a considerable amount of iron-binding phenolic groups. Yod Kratin (leaves of the lead tree) is a very popular vegetable in Thailand. It is consumed at least once a week year round, sometimes every day, together with the main meal.

Calcium: effect of different amounts on nonheme- and heme-iron absorption in humans.

We investigated the effect of calcium on iron absorption in 126 human subjects. Addition of calcium chloride to wheat rolls significantly reduced iron absorption. Doses between 40 and 600 mg Ca were studied.

Rice and iron absorption in man.

Several studies suggest that iron absorption is low from rice-based meals. Comparisons of the effect of rice starch and wheat starch on iron absorption showed that rice had no effect on absorption. Observed differences in effects on iron absorption between different batches of rice starch could be explained by differences in the phytate content.