THE ROLE OF VITAMIN-A ON THE INHIBITORS OF NONHEME IRON-ABSORPTION - PRELIMINARY-RESULTS

The interaction of vitamin vitamin A and inhibitors of iron absorption from a basal breakfast containing bread from either 100 g of precooke d maize flour or 100 g of wheat flour + 50 g of cheese + 10 g of marga rine was studied. These breads were labeled with either Fe-55 or Fe-59 . This basal breakfast was given alone on the first day of the study, and a beverage containing coffee or tea at different concentrations wa s administered with this breakfast on the following days. In the first three experiments performed, the bread was made from commercially ava ilable flours, fortified with iron as ferrous fumarate and vitamins. I t can be noticed that whereas the iron absorption from the breakfast c ontaining wheat bread was significantly reduced when given with differ ent concentrations of coffee bevel ages, the bioavailability of iron f rom the breakfast containing precooked maize bread remained the same i n spite of being administered with increasing concentrations of coffee beverages. The only ingredient present in precooked maize bread and n ot in wheat bread was vitamin A. In the other experiments, il on and v itamin A were added to the non-fortified precooked maize pour in our l aboratory. In presence of vitamin A, nonheme iron absorption from the basal breakfast containing either coffee or tea was not statistically different from the breakfast without coffee, meaning that vitamin A ca n overcome the inhibition of coffee and tea on iron absorption and als o prevents the inhibitory effect of phytates. The high performance liq uid chromatography and spectrophotometric studies seem to indicate tha t during the digestive process, iron and vitamin A form a new prouct o r complex, that keeps iron soluble even at pH6. All these data suggest that vitamin A binds ii on liberated during digestive process and act s as a quelating agent, keeping ir-on soluble in the intestinal lumen and pl eventing the inhibition of polyphenols and phytates on nonheme iron absorption. (C) Elsevier Science Inc. 1997.