Vitamin A and β-Carotene Can Improve Nonheme Iron Absorption from Rice, Wheat and Corn by Humans

Abstract

After the rapid decrease in the prevalence of iron deficiency and iron-deficiency anemia in the Venezuelan population when a national program for fortification of flours with iron and vitamins was instituted, we studied micronutrient interactions in Venezuelan diets. One hundred human adults were fed three cereal-based diets, labelled with either 59Fe or 55Fe in six studies. Each diet contained different concentrations of vitamin A (from 0.37 to 2.78 micromol/100 g cereal) or beta-carotene (from 0.58 to 2.06 micromol/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 threefold for rice and 1.8-fold for wheat and corn, suggesting that both compounds prevented the inhibitory effect of phytates on iron absorption. Increasing the doses of vitamin A or beta-carotene did not further significantly increase iron absorption. We measured the iron remaining in solution performing in vitro studies in which the pH of solutions was adjusted from 2 to 6 in the presence of vitamin A or beta-carotene. All of the iron from ferrous fumarate was soluble after changing the pH of the solution containing 3.4 micromol of beta-carotene to 6.0. Vitamin A was less effective. However, 78 +/- 18% of iron was soluble in the presence of 3.3 micromol of vitamin A, whereas with no vitamin addition, only 26 +/- 13% of iron was soluble (<0.05). Vitamin A and beta-carotene may form a complex with iron, keeping it soluble in the intestinal lumen and preventing the inhibitory effect of phytates and polyphenols on iron absorption.

Associations of iron status with dietary and other factors in 6-year-old children

“…Variety meat is recognized to be an especially good source of iron, and the present findings appear to confirm that. However, as frequently reported (Duggan et al, 1991;Thane et al, 2000;Gunnarsson et al, 2004) iron intake is not related with iron status in the present study, but the proportion of haeme-iron is relatively high in variety meat as in other meat products; also it often contains quite large amounts of retinol, which was recently reported to enhance iron absorption, although results are mixed (Garcia-Casal et al, 1998;Walczyk et al, 2003). In the present study, retinol intake did not correlate with the iron status indices.…”

Nutritionally Enhanced Staple Food Crops

“…Green leafy vegetables and orange/yellow colored fruits are rich source of carotenoids, and a beneficial effect of vitamin A and b-carotene on enhanced nonheme irons absorption has been reported (Garcıa-Casal et al 1998;Layrisse et al 2000). The presence of vitamin A increases iron absorption up to 3 times for rice, 2.4 times for wheat, and 1.8 times for maize, while b-carotene increases iron absorption almost 3 times, showing that both compounds prevent the inhibitory effect of phytates on iron absorption (Layrisse et al 2000).…”

The anemia of vitamin A deficiency: epidemiology and pathogenesis

“…A recent study suggests that gut integrity in infants, as measured by a urinary lactulose : mannitol excretion test, is influenced by vitamin A supplementation (Thurnham et al, 2000), and these findings suggest another mechanism by which vitamin A status could affect the absorption of nutrients involved in erythropoiesis. In studies using cereal-based diets with labelled 59 Fe or 55 Fe, both vitamin A and beta-carotene enhanced the absorption of nonheme iron in human adults (García-Casal et al, 1998).…”