White Beans Provide More Bioavailable Iron than Red Beans: Studies in Poultry (Gallus gallus) and an in vitro Digestion/Caco-2 Model

Department of Food Science, Cornell University, Ithaca, NY 14853, USA.
International Journal for Vitamin and Nutrition Research (Impact Factor: 0.85). 12/2010; 80(6):416-29. DOI: 10.1024/0300-9831/a000028
Source: PubMed


Iron-biofortification of crops is a strategy that alleviates iron deficiency. The common bean (Phaseolus vulgaris L.) is an attractive candidate for biofortification. However, beans are high in polyphenols that may inhibit iron absorption. In vitro studies have shown that iron bioavailability from white beans is higher than that from colored beans. In this study, our objective was to determine if white beans contain more bioavailable iron than red beans and to determine if the in vitro observations of bean-iron bioavailability would be evident in an in vivo feeding trial. We compared iron bioavailability between diets containing either white (Matterhorn) or red (Merlot) beans, which differ in polyphenol content. One-week-old chicks (Gallus gallus) were divided into four groups: 1. "WB": 40% white-bean diet; 2. "RB" :40% red-bean diet; 3. "WB+Fe": 40% white-bean diet; 4. "RB+Fe": 40% red-bean diet (51, 47, 179, and 175 ppm iron, respectively). Diets 1 and 2 had no supplemental iron; whereas 125 µg/g iron was added to diets 3 and 4. For 8 weeks, hemoglobin, feed consumption, and body weights were measured. Divalent metal transporter 1 (iron-uptake-transporter), duodenal-cytochrome-B (iron reductase), and ferroportin (iron-exporter) expressions were higher (p<0.05), villus-surface-area (tissue iron-deficiency adaptation) was greater in the "RB" group vs. other groups. Cecal microflora was similar between treatments. Hemoglobin, body-hemoglobin iron, and body weights were lower in the "RB" group vs. other groups (p<0.05). In vitro analysis showed lower ferritin formation (less bioavailable iron) in cells exposed to the "RB" diet. We conclude that the in vivo results support the in vitro observations; i. e., white beans contain more bioavailable iron than red beans.

Download full-text


Available from: Elad Tako, Jan 27, 2015
    • "The protocols used in the analysis of concentrations of ferritin and total protein of the Caco-2 cells subjected to the meal plan models were similar to those previously described[15]. Ferritin and total protein concentrations were determined on an aliquot of the harvested cell suspension with a one-stage sandwich immunoradiometric assay (FER-IRON II Ferritin assay, Ramco Laboratories) and a colorimetric assay (Bio-Rad DC Protein assay), respectively. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background. Iron deficiency is the most common nutrient deficiency worldwide. Large intakes of micronutrient-poor staple crops, coupled with low intakes of highly bioavailable dietary iron, are a major cause of this deficiency.Objective. To examine the concentration and relative bioavailability of iron in several models (n = 23) of traditional Bangladeshi meals (rice, lentils/dal, vegetable, and fish), as well as the effect of removal of the lentil seed coat on the nutritional quality of iron.Methods. The relative bioavailability of iron was assessed by the in vitro/Caco-2 cell culture method, iron concentration by an inductively coupled argon-plasma emission spectrometer (ICAP-ES), and phytic acid concentration by colorimetric assay. The recipes contained 75% to 85% rice, 0% to 15% dal (containing whole or dehulled lentils), 0% to 15% vegetable curry, and 0% to 8% fish.Results. While the iron concentrations of recipes containing dehulled dal were significantly lower than those of recipes containing whole dal (p = .005), seed coat removal doubled relative iron bioavailability and increased phytic acid concentration (p r = 0.48, p = .03), but not whole dal (r = – 0.047, p = .84).Conclusions. The total amount of iron absorbed from traditional Bangladeshi meals is dependent upon iron concentration, and dehulling lentils removes inhibitory factors increasing iron uptake but also increases the density of phytic acid in the lentil sample. Thus, along with breeding for high iron concentration and bioavailability (i.e., biofortification), seed coat removal plus measures to lower phytic acid concentrations may be an important strategy to improve the bioavailability of iron in lentils and other pulse crops.
    No preview · Article · Dec 2014 · Food and nutrition bulletin
  • Source
    • "The protocols used in the ferritin and total protein contents analyses of Caco-2 cells were similar to those previously described [8,29,9,28,30]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Currently, there is a lot of interest in improving gut health, and consequently increasing Fe absorption, by managing the colonic microbial population. This is traditionally done by the consumption of probiotics, live microbial food supplements. However, an alternative, and often very effective approach, is the consumption of food ingredients known as prebiotics. Fructans and arabinoxylans are naturally occurring non-digestible oligosaccharides in wheat that exhibit prebiotic properties and may enhance intestinal iron (Fe) absorption. The aim of this study was to assess the effect of prebiotics from wheat on Fe bioavailability in vitro (Caco-2 cells) and in vivo (broiler chickens, Gallus gallus). Methods In the current study, the effect of intra-amniotic administration of wheat samples extracts at 17 d of embryonic incubation on the Fe status and possible changes in the bacterial population in intestinal content of broiler hatchlings were investigated. A group of 144 eggs were injected with the specified solution (1 ml per egg) into the amniotic fluid. Immediately after hatch (21 d) and from each treatment group, 10 chicks were euthanized and their small intestine, liver and cecum were removed for relative mRNA abundance of intestinal Fe related transporters, relative liver ferritin amounts and bacterial analysis of cecal content, respectively. Results The in vivo results are in agreement with the in vitro observations, showing no differences in the hatchling Fe status between the treatment groups, as Fe bioavailability was not increased in vitro and no significant differences were measured in the intestinal expression of DMT1, Ferroportin and DcytB in vivo. However, there was significant variation in relative amounts of bifidobacteria and lactobacilli in the intestinal content between the treatments groups, with generally more bifidobacteria being produced with increased prebiotic content. Conclusions In this study we showed that prebiotics naturally found in wheat grains/bread products significantly increased intestinal beneficial bacterial population in Fe deficient broiler chickens. With this short-term feeding trial we were not able to show differences in the Fe-status of broilers. Nevertheless, the increase in relative amounts of bifidobacteria and lactobacilli in the presence of wheat prebiotics is an important finding as these bacterial populations may affect Fe bioavailability in long-term studies.
    Full-text · Article · Jun 2014 · Nutrition Journal
  • Source
    • "The avian ferritins corresponded to a weight of approximately 470 to 500 kDa [7-9,24-26,28]. No significant differences in liver Fe or liver ferritin concentrations were measured between the treatment groups (n = 6, P > 0.05). The mean values of ferritin protein and the amount of iron present in the ferritin of the liver samples of all animals are presented in Table  3. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Our objective was to determine if a biofortified variety of black bean can provide more bioavailable-iron (Fe) than a standard variety. Two lines of black beans (Phaseolus-vulgaris L.), a standard (DOR500; 59mug Fe/g) and biofortified (MIB465; 88mug Fe/g) were used. The DOR500 is a common commercial variety, and the MIB465 is a line developed for higher-Fe content. Given the high prevalence of Fe-deficiency anemia worldwide, it is important to determine if Fe-biofortified black beans can provide more absorbable-Fe. Black bean based diets were formulated to meet the nutrient requirements for the broiler (Gallus-gallus) except for Fe (dietary Fe-concentrations were 39.4+/-0.2 and 52.9+/-0.9 mg/kg diet, standard vs. biofortified, respectively). Birds (n=14) were fed the diets for 6-weeks. Hemoglobin-(Hb), liver-ferritin and Fe-related transporter/enzyme gene-expression were measured. Hemoglobin-maintenance-efficiency and total-body-Hb-Fe values were used to estimate Fe-bioavailability. Hemoglobin-maintenance-efficiency values were higher (P<0.05) in the group consuming the standard-Fe beans on days 14, 21 and 28; indicating a compensatory response to lower dietary-Fe. Final total-Hb-Fe body content was higher in the biofortified vs. the standard group (26.6+/-0.9 and 24.4+/-0.8 mg, respectively; P<0.05). There were no differences in liver-ferritin or in expression of DMT-1, Dcyt-B, and ferroportin. In-vitro Fe-bioavailability assessment indicated very low Fe-bioavailability from both diets and between the two bean varieties (P>0.05). Such extremely-low in-vitro Fe-bioavailability measurement is indicative of the presence of high levels of polyphenolic-compounds that may inhibit Fe-absorption. High levels of these compounds would be expected in the black bean seed-coats. The parameters of Fe-status measured in this study indicate that only a minor increase in absorbable-Fe was achieved with the higher-Fe beans. The results also raise the possibility that breeding for increased Fe-concentration elevated the levels of polyphenolic-compounds that can reduce bean Fe-bioavailability, although the higher levels of polyphenolics in the higher-Fe beans may simply be coincidental or an environmental effect. Regardless, Fe-biofortified beans remain a promising vehicle for increasing intakes of bioavailable-Fe in human populations that consume high levels of these beans as a dietary staple, and the bean polyphenol profile must be further evaluated and modified if possible in order to improve the nutritional quality of higher-Fe beans.
    Full-text · Article · Mar 2014 · Nutrition Journal
Show more