Iron and zinc bioavailability in rats fed intrinsically labeled bean and bean-rice infant weaning food products

Biological Application of a Fluorescent Zinc Sensing Probe for the Analysis of Zinc Bioavailability Using Caco-2 Cells as an In-Vitro Cellular Model

Zinc is essential for growth and development of all living organisms, especially human being. Deficiency of micronutrients like zinc and iron has been linked to the manifestation of hidden hunger. Therefore, it is imperative that development of some rapid screening method for bioavailable zinc in various crops and food commodities would be an essential addition in battle against zinc deficiency related hidden hunger. One such method could be the usage of fluorescence based zinc ion sensing probe which would be robust and convenient for estimating bioavailable zinc. To address this issue, NBD-TPEA, a highly sensitive zinc ion sensing probe, have been used in this study towards the development of a novel fluorescence based approach for the analysis of zinc bioavailability in Caco-2 cells as an in-vitro cellular model. The use of this probe showed dose dependent sensitivity towards increasing concentrations of zinc ion uptake by Caco-2 cells. It also showed specificity for zinc ion uptake as compared to other metal ions in-vitro. These observations correlated extremely well with zinc uptake analysis by cell imaging and conventional analytical technique like, ICP-MS. The developed assay was then tested in mushroom and some selected biofortified derivatives of wheat for determining the levels of their bioavailable zinc using Caco-2 cells. The data as obtained with these food samples in our developed bioassay correlated well with the other sophisticated analytical techniques thus validating our cell based assay. Hence, the developed assay could serve as a simple but sensitive tool for determining bioavailable zinc in various food samples.

A Survey of Plant Iron Content-A Semi-Systematic Review

Iron is an essential mineral nutrient for all living organisms, involved in a plurality of biological processes. Its deficit is the cause of the most common form of anemia in the world: iron deficiency anemia (IDA). This paper reviews iron content in various parts of 1228 plant species and its absorption from herbal products, based on data collected from the literature in a semi-systematic manner. Five hundred genera randomly selected from the Angiosperms group, 215 genera from the Pteridophytes groups and all 95 Gymnosperm genera as listed in the Plant List version 1.1 were used as keywords together with the word "iron" in computerized searches. Iron data about additional genera returned by those searches were extracted and included in the analysis. In total, iron content values for a number of 1228 species, 5 subspecies, and 5 varieties were collected. Descriptive and inferential statistics were used to compare iron contents in various plant parts (whole plant, roots, stems, shoots, leaves, aerial parts, flowers, fruits, seeds, wood, bark, other parts) and exploratory analyses by taxonomic groups and life-forms were carried out. The absorption and potential relevance of herbal iron for iron supplementation are discussed.

Iron bioavailability of common beans (Phaseolus vulgaris L.) intrinsically labeled with (59)Fe

A radiobioassay was performed in rats with or without iron depletion to evaluate the iron bioavailability of diets enriched with common beans and with "multimixture", a nutritional supplement based on parts of foods that are not usually eaten. The full-body (59)Fe level was determined after 5h, the absorbed (59)Fe level was determined after 48 h, and the amount of (59)Fe retained was determined after 7 days. Iron bioavailability was assessed by the full-body radioactivity of the animals, determined using a solid scintillation detector. The iron bioavailability of common beans was higher in the iron-depleted animals (55.7%) than in the non-depleted animals (25.12%) because of the higher absorption rate in the iron-depleted animals. The multimixture did not influence dietary iron bioavailability. In addition, the iron bioavailability of common beans was similar to that observed in the standard source of iron for Wistar rats. Hence, common beans may be considered an adequate dietary iron source because of its high bioavailability.

Protein quality evaluation twenty years after the introduction of the protein digestibility corrected amino acid score method

In 1989 the Joint FAO/WHO Expert Consultation on Protein Quality Evaluation recommended the use of the Protein Digestibility Corrected Amino Acid Score (PDCAAS) method for evaluating protein quality. In calculating PDCAAS, the limiting amino acid score (i.e., ratio of first limiting amino acid in a gram of target food to that in a reference protein or requirement) is multiplied by protein digestibility. The PDCAAS method has now been in use for 20 years. Research emerging during this time has provided useful data on various aspects of protein quality evaluation that has made a review of the current methods used in assessing protein quality necessary. This paper provides an overview of the use of the PDCAAS method as compared to other methods and addresses some of the key challenges that remain in regards to protein quality evaluation. Furthermore, specific factors influencing protein quality including the effects of processing conditions and preparation methods are presented. Protein quality evaluation methods and recommended protein intakes currently used in different countries vis-à-vis the WHO/FAO/UNU standards are further provided. As foods are frequently consumed in complement with other foods, the significance of the PDCAAS of single protein sources may not be evident, thus, protein quality of some key food groups and challenges surrounding the calculation of the amino acid score for dietary protein mixtures are further discussed. As results from new research emerge, recommendations may need to be updated or revised to maintain relevance of methods used in calculating protein quality.

Bioavailability of iron in the regional basic diet (RBD) with dietary supplement in Brazil

The consumption of the regional basic diet (RBD) determines a state of malnutrition found in the low-income population of Northeastern Brazil. A dietary supplement known as multimixture has been used as an alternative source of iron in food for the prevention and/or treatment of anemia and for the recovery from malnutrition. The purpose of the present work was to evaluate the bioavailability of iron in the RBD supplemented with multimixture in iron-depleted and non-depleted Wistar rats. To produce iron depletion in the animals, pretest depletion diets without iron and the pretest control diet based on the AIN-93 diet were used for 8 weeks. This phase was followed by the test diets: control, AIN-93 extrinsically labeled with (59)FeCl(3); RBD, containing carioca beans intrinsically labeled with (59)Fe; and RBDMM, RBD plus multimixture, supplied in a single meal. Hemoglobin concentration, weight gain, and dietary intake were determined in the pretest phase. Iron bioavailability was determined by the determination of total-body radiation in the animals for 7 days, using a solid scintillation detector. The hemoglobin concentration, weight gain, and dietary intake were greater in the non-depleted animals than in the iron-depleted ones. The iron bioavailability of the diets did not differ significantly. It was concluded that the multimixture did not affect the bioavailability of Fe contained in the beans of the RBD.

Iron and zinc bioavailabilities to pigs from red and white beans (Phaseolus vulgaris L.) are similar

Common beans contain relatively high concentrations of iron (Fe) and zinc (Zn) but are also high in polyphenols and phytates, factors that may inhibit Fe and Zn absorption. In vitro (Caco-2 cells) and in vivo (pigs) models were used to compare Fe and Zn bioavailabilities between red and white beans, which differ in polyphenol content. Bean/maize diets containing 37% of either white or red cooked beans were formulated. Fe uptake by Caco-2 cells was 14-fold higher from the white bean diet compared to the red bean diet. The diets were fed to anemic piglets (n = 10) for 35 days. On experiment days 7 and 21, pigs were given meals containing beans intrinsically labeled with stable isotopes of Fe and Zn ((58)Fe, (70)Zn), followed by intravenous (iv) injections of (54)Fe and (67)Zn, to assess Fe and Zn absorption. Isotope ratios determined by inductively coupled plasma mass spectrometry in whole blood and plasma samples were used to calculate iron and zinc absorption, respectively. On day 35, animals were killed and duodenal sections were collected for DMT1 gene expression analysis. Fe absorption was 14 and 16% from the first labeled meal and 9 and 10.5% from the second labeled meal for the white and red beans, respectively (P > 0.05). Zn absorption was 28 and 23% from the first meal (P > 0.05) and 31 and 29% from the second meal (P > 0.05) for the white and red beans, respectively. DMT1 gene expression did not differ between treatments. It was concluded that bean color does not affect Fe or Zn bioavailability in vivo and that beans are a good source of bioavailable Fe and Zn.

Iron bioavailability to piglets from red and white common beans (Phaseolus vulgaris)

Polyphenols in foods may chelate dietary Fe and lower its bioavailability. Concentrations of phenols are higher in red beans than in white beans. The aim of this study was to compare iron bioavailabilities from red and white beans in a piglet hemoglobin repletion model. Fe deficient cross bred piglets (Hampshire x Landrace x Yorkshire) were used. Nutritionally balanced diets (except for Fe) were formulated to contain 50% precooked, dehydrated beans (either small red or Great Northern white). At age 5 weeks, the piglets were assigned to two groups and fed diets containing either red or white beans for 4 weeks. Weight and hemoglobin (Hb) concentrations were monitored weekly. Feed intakes were measured daily. Hemoglobin repletion efficiency (HRE) was calculated as the gain in total body hemoglobin Fe (Hb-Fe) divided by Fe intake. Hb concentrations, Hb-Fe gains, and HRE were not different between the groups at any time point ( p > 0.05). HRE values in the red bean group were 50% in the first week and 30% over the entire 4 week period. In the white bean group, they were 56 and 26%, respectively. Proline-rich protein mRNA concentrations in parotid glands were higher in the red bean group compared to the white bean group. These results show that iron bioavailabilities from red and white beans are similar and suggest that pigs adapt to the inhibitory effects of polyphenols on iron absorption by increasing the secretion of protective proline-rich proteins in the saliva.

Influence of germination and fermentation on bioaccessibility of zinc and iron from food grains

OBJECTIVE AND DESIGN

Food grains such as green gram, chickpea and finger millet are often subjected to traditional processing involving germination and fermentation. This study was designed to assess the effect of germination of these grains on the bioaccessibility of zinc and iron. The effect of fermentation of a cereal-pulse combination as encountered in the preparation of breakfast dishes - idli, dosa and dhokla - on the same was also evaluated. Bioaccessibility measurement was made employing an in vitro simulated digestion method.

RESULT

Zinc bioaccessibility was significantly decreased by germination (48 h) of finger millet (38%) and green gram (44%), while iron bioaccessibility was increased by 62% (green gram), 39% (chickpea) and 20% (finger millet), concomitant with a reduction in tannin content. A fermented batter of rice+black gram - 2:1 (idli) and 3:1 (dosa) - had higher bioaccessibility values for zinc (71 and 50%, respectively), while iron bioaccessibility values were increased in these cases of fermentation to an even greater extent, namely 277 and 127%, respectively. Zinc and iron bioaccessibility was not improved by fermentation of the combination of chickpea, green gram, black gram and rice (1:1:0.5:0.5; dhokla). A fermentation of cereal-legume combinations of idli and dosa batter significantly reduced both phytate and tannin, while in the case of dhokla batter there was a continued significant presence of phytate associated with additional legumes - chickpea and green gram.

CONCLUSION

Germination of food grains improved the bioaccessibility of iron but not that of zinc. Fermentation of a batter of cereal-pulse combination in the preparation of idli and dosa enhanced the bioaccessibility of both zinc and iron, but not that of the combination used for the preparation of dhokla.