VITAMIN-A AND BETA-CAROTENE CAN IMPROVE NONHEME IRON-ABSORPTION FROM RICE, WHEAT AND CORN BY HUMANS

After the rapid decrease in the prevalence of iron deficiency and iron -deficiency anemia in the Venezuelan population when a national progra m for fortification of flours with iron and vitamins was instituted, w e studied micronutrient interactions in Venezuelan diets. One hundred human adults were fed three cereal-based diets, labelled with either F e-59 or Fe-55 in six studies. Each diet contained different concentrat ions of vitamin A (from 0.37 to 2.78 mu mol/100 g cereal) or beta-caro tene (from 0.58 to 2.06 mu mol/100 g cereal). The presence of vitamin A increased iron absorption up to twofold for rice, 0.8-fold for wheat and 1.4-fold for corn, beta-carotene increased absorption more than t hreefold for rice and 1.8-fold for wheat and corn, suggesting that bot h compounds prevented the inhibitory effect of phytates on iron absorp tion. Increasing the doses of vitamin A or beta-carotene did not furth er significantly increase iron absorption. We measured the iron remain ing in solution performing in vitro studies in which the pH of solutio ns was adjusted from 2 to 6 in the presence of vitamin A or beta-carot ene. All of the iron from ferrous fumarate was soluble after changing the pH of the solution containing 3.4 mu mol of beta-carotene to 6.0. Vitamin A was less effective. However, 78 +/- 18% of iron was soluble in the presence of 3.3 mu mol of vitamin A, whereas with no vitamin ad dition, only 26 +/- 13% of iron was soluble (<0.05). Vitamin A and bet a-carotene may form a complex with iron, keeping it soluble in the int estinal lumen and preventing the inhibitory effect of phytates and pol yphenols on iron absorption.