Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/20/2006
Publication Date: 4/16/2007
Citation: Beisiegel, J.M., Hunt, J.R., Glahn, R.P., Welch, R.M., Menkir, A., Maziya-Dixon, B.B. 2007. Iron bioavailability from maize and beans: a comparison of human and Caco-2 cell measurements [abstract]. Program Abstracts, Consequences and Control of Micronutrient Deficiencies: Science, Policy, and Programs - Defining the Issues. April 16-18, 2007. Istanbul, Turkey. p. 103.
Technical Abstract: Background: An in vitro digestion/Caco-2 cell model may predict iron bioavailability to humans, but direct comparisons are lacking. Aims: To confirm previous in vitro iron bioavailability differences between two maize varieties and between white vs. colored beans, directly comparing human and Caco-2 cell results. Methods: Two randomized, 2 x 2 factorial, 29-d experiments compared women’s iron absorption (n=26) from two maize varieties (ACR vs. TZB) or great northern vs. pinto beans (n = 13). Each food was served with and without orange juice to provide ascorbic acid. Nonheme iron bioavailability was determined from 2-wk whole body and erythrocyte retention of extrinsically added radioiron tracers, and compared with Caco-2 cell results from identical meals. Results: In contrast to results with previous harvests, in vitro results predicted no difference in iron availability between the maize varieties. Maize varieties did not affect percent iron absorption, but women tended (p = 0.06) to absorb 4-7 µg more iron/meal from ACR compared to TZB, because of a slightly higher corn iron content (0.8 vs 0.7 mg/meal, respectively, p <0.0001). Contrary to in vitro predictions, iron absorption did not differ between bean varieties. As predicted in vitro for all but the pinto beans, Ascorbic acid increased iron absorption from all foods by at least 3 times (p<0.0001). Conclusion: Caco-2 cell results correctly predicted ascorbic acid enhancement of iron bioavailability to humans from maize and great northern beans, but incorrectly predicted color-associated differences between bean varieties and their interaction with AA.