Iron bioavailability from maize and beans: a comparison of human measurements with Caco-2 cell and algorithm predictions

Abstract

Background: An in vitro digestion and Caco-2 cell model may predict iron bioavailability to humans; however, direct comparisons are lacking. Objective: The objective was to test the differences in iron bioavailability between 2 maize varieties and 2 bean varieties (white beans and colored beans) by comparing human, Caco-2, and algorithm results. Design: Two randomized, 2 ҂ 2 factorial experiments compared women's iron absorption from 2 maize varieties (ACR and TZB; n ҃ 26) and 2 bean varieties (great northern and pinto; n ҃ 13), each fed with and without ascorbic acid (AA) from orange juice. Nonheme iron bioavailability was determined from 2-wk retention of extrinsic radioiron tracers and was compared with Caco-2 cell and algorithm results from identical meals. Results: Without AA supplementation, women absorbed only about 2% of the iron from the maize or bean meals. The results were unaffected by the variety of either maize or beans. Adding AA (15-20 molar ratios of AA:iron) roughly tripled the iron absorption (P 0.0001) from all test meals. Although the Caco-2 model predicted a slightly improved bioavailability of iron from ACR maize than from TZB maize (P 0.05), it accurately predicted relative iron absorption from the maize meals. However, the Caco-2 model inaccurately predicted both a considerable difference between bean varieties (P 0.0001) and a strong interaction between bean varieties and enhancement by AA (P 0.0001). The algorithm method was more qualitatively than quantitatively useful and requires further development to accurately predict the influence of polyphenols on iron absorption. Conclusions: Caco-2 predictions confirmed human iron absorption results for maize meals but not for bean meals, and algorithm predictions were only qualitatively predictive. 2007;86:388 -96. Am J Clin Nutr

Increase of soybean nutritional quality with nonstandard foliar fertilizers

“…This could indicate that factors which are responsible for a decrease of the phytate content in soybean grain could also increase the Fe content to a high degree (explained variance of 2.185), while β-carotene and Mg were positively related, but to a lesser extent (explained variance of 0.884), and were influenced by other factors. Moreover, studies with maize and beans did not support a lower Fe availability from grains with a slightly higher phytate content (Beiseigel et al, 2007), while significance was given to factors that improve Fe availability, such as ascorbic acid, as well as β-carotene, which was included in the present study. Table 6.…”

Comparison betweenin vitroandin vivomethods to screen iron bioavailability

“…Many studies provide support for the validity of using cell ferritin as an index of bioavailability and this model was qualitatively and quantitatively validated under different conditions (Au & Reddy, 2000;Glahn, Lai, Hsu, Thompson, & Van Campen, 1998;Glahn, Rassier, Goldman, Lee, & Cha, 2000;Glahn, Wien, Van Campen, & Miller, 1996;Glahn, Wortley, South, & Miller, 2002;Hunt & Roughhead, 1999;Roughhead & Hunt, 2000). However, the in vitro digestion/Caco-2 model requires experienced technicians and good quality cell-culture facilities to obtain reproducible results (Argyri, Birba, Miller, Komaitis, & Kapsokefalou, 2009) and according to Beisegel et al (2007) the in vitro digestion/Caco-2 model has limitations in the predictions of iron bioavailability in certain food matrices like beans.…”

Characterization of Caco-2 and HT29-MTX cocultures in an in vitro digestion/cell culture model used to predict iron bioavailability☆

“…Results from quantitative studies comparing in vivo human to in vitro Caco-2 iron uptake results for semisynthetic meals have shown that human and Caco-2 data generally agree [9][10][11]. Yun et al [10] determined that the Caco-2 model can be used to estimate human iron bioavailability from complex meals if the results can be compared as absorption ratios, which are the iron absorption at a given level of promoter or inhibitor divided by the iron absorption without the promoter or inhibitor present.…”