The Combined Application of the Caco-2 Cell Bioassay Coupled with In Vivo (Gallus gallus) Feeding Trial Represents an Effective Approach to Predicting Fe Bioavailability in Humans

Critical assessment of wheat biofortification for iron and zinc: a comprehensive review of conceptualization, trends, approaches, bioavailability, health impact, and policy framework

Addressing global hidden hunger, particularly in women of childbearing age and children under five, presents a significant challenge, with a focus on iron (Fe) and zinc (Zn) deficiency. Wheat, a staple crop in the developing world, is crucial for addressing this issue through biofortification efforts. While extensive research has explored various approaches to enhance Fe and Zn content in wheat, there remains a scarcity of comprehensive data on their bioavailability and impact on human and animal health. This systematic review examines the latest trends in wheat biofortification approaches, assesses bioavailability, evaluates the effects of biofortified wheat on health outcomes in humans and animals, and analyzes global policy frameworks. Additionally, a meta-analysis of per capita daily Fe and Zn intake from average wheat consumption was conducted. Notably, breeding-based approaches have led to the release of 40 biofortified wheat varieties for commercial cultivation in India, Pakistan, Bangladesh, Mexico, Bolivia, and Nepal, but this progress has overlooked Africa, a particularly vulnerable continent. Despite these advancements, there is a critical need for large-scale systematic investigations into the nutritional impact of biofortified wheat, indicating a crucial area for future research. This article can serve as a valuable resource for multidisciplinary researchers engaged in wheat biofortification, aiding in the refinement of ongoing and future strategies to achieve the Sustainable Development Goal of eradicating hunger and malnutrition by 2030.

Assessing the Interactions between Zinc and Vitamin A on Intestinal Functionality, Morphology, and the Microbiome In Vivo (Gallus gallus)

Dietary deficiencies in zinc (Zn) and vitamin A (VA) are among the leading micronutrient deficiencies globally and previous research has proposed a notable interaction between Zn and VA physiological status. This study aimed to assess the effects of zinc and vitamin A (isolated and combined) on intestinal functionality and morphology, and the gut microbiome (Gallus gallus). The study included nine treatment groups (n~11)-no-injection (NI); H₂O; 0.5% oil; normal zinc (40 mg/kg ZnSO₄) (ZN); low zinc (20 mg/kg) (ZL); normal retinoid (1500 IU/kg retinyl palmitate) (RN); low retinoid (100 IU/kg) (RL); normal zinc and retinoid (40 mg/kg; 1500 IU/kg) (ZNRN); low zinc and retinoid (ZLRL) (20 mg/kg; 100 IU/kg). Samples were injected into the amniotic fluid of the fertile broiler eggs. Tissue samples were collected upon hatch to target biomarkers. ZLRL reduced ZIP4 gene expression and upregulated ZnT1 gene expression (p < 0.05). Duodenal surface area increased the greatest in RL compared to RN (p < 0.01), and ZLRL compared to ZNRN (p < 0.05). All nutrient treatments yielded shorter crypt depths (p < 0.01). Compared to the oil control, ZLRL and ZNRN reduced (p < 0.05) the cecal abundance of Bifidobacterium and Clostridium genera (p < 0.05). These results suggest a potentially improved intestinal epithelium proceeding with Zn and VA intra-amniotic administration. Intestinal functionality and gut bacteria were modulated. Further research should characterize long-term responses and the microbiome profile.

Intestinal absorption of DHA microcapsules with different formulations based on ex vivo rat intestine and in vitro dialysis models

Intestinal permeability is a key factor affecting the bioavailability and physiological efficacy of docosahexaenoic acid (DHA) encapsulated in microcapsules. However, how the DHA microcapsules are transformed and the components absorbed across the small intestinal membrane has seldom been examined previously. In this study, an ex vivo absorption model based on the permeability of the rat small intestine was established to evaluate the intestinal absorption of DHA microcapsules with five formulations after gastrointestinal digestion in vitro. For pure glucose solutions, the apparent permeability coefficient (P_app) increased from 5.70 ± 0.60 × 10^-6 cm s^-1 at 5 mg mL^-1 to 20.25 ± 0.88 × 10^-6 cm s^-1 at 30 mg mL^-1 and decreased to 15.73 ± 0.91 × 10^-6 cm s^-1 at 100 mg mL^-1. The P_app values obtained using the ex vivo model are comparable to those reported in the human jejunum. For algal oil DHA microcapsules with whey protein as the wall material (A-WP-DHA) after in vitro digestion, the P_app of glucose released was 3.81 × 10^-6 cm s^-1 with an absorption ratio of 59.55% in the ex vivo model, significantly lower than that from the in vitro porcine casing model. The P_app and absorption ratio varied little among the in vitro dialysis models with different molecular weight cut-off values. A similar trend was observed for the absorption of amino acids. However, the absorption ratio (26.6%) was the highest in the ex vivo model for free fatty acids (FFAs) released from the microcapsules due to the rapid accumulation of compounds on the inner wall of the intestinal sac. In addition, the DHA microcapsules with algal oil as the DHA source (36.40%) exhibited a higher absorption ratio of FFAs than that from tuna oil (14.26%) in the ex vivo model. The wall material compositions seemed to have little effect on FFA absorption. The present study is practically meaningful for the future formulation of DHA microcapsules with enhanced absorption.

Alterations in Intestinal Brush Border Membrane Functionality and Bacterial Populations Following Intra-Amniotic Administration (Gallus gallus) of Nicotinamide Riboside and Its Derivatives

Nicotinamide riboside (NR) acts as a nicotinamide adenine dinucleotide (NAD+) precursor where NR supplementation has previously been shown to be beneficial. Thus, we synthesized and characterized nicotinamide riboside tributyrate chloride (NRTBCl, water-soluble) and nicotinamide riboside trioleate chloride (NRTOCl, oil-soluble) as two new ester derivatives of nicotinamide riboside chloride (NRCl). NRCl and its derivatives were assessed in vivo, via intra-amniotic administration (Gallus gallus), with the following treatment groups: (1) non-injected (control); and injection of (2) deionized H₂O (control); (3) NRCl (30 mg/mL dose); (4) NRTBCl (30 mg/mL dose); and (5) NRTOCl (30 mg/mL dose). Post-intervention, the effects on physiological markers associated with brush border membrane morphology, intestinal bacterial populations, and duodenal gene expression of key proteins were investigated. Although no significant changes were observed in average body weights, NRTBCl exposure increased average cecum weight. NR treatment significantly increased Clostridium and NRCl treatment resulted in increased populations of Bifidobacterium, Lactobacillus, and E. coli. Duodenal gene expression analysis revealed that NRCl, NRTBCl, and NRTOCl treatments upregulated the expression of ZnT1, MUC2, and IL6 compared to the controls, suggesting alterations in brush border membrane functionality. The administration of NRCl and its derivatives appears to trigger increased expression of brush border membrane digestive proteins, with added effects on the composition and function of cecal microbial populations. Additional research is now warranted to further elucidate the effects on inflammatory biomarkers and observe changes in the specific intestinal bacterial populations post introduction of NR and its derivatives.

Saffron (Crocus sativus L.) Flower Water Extract Disrupts the Cecal Microbiome, Brush Border Membrane Functionality, and Morphology In Vivo (Gallus gallus)

Saffron (Crocus sativus L.) is known as the most expensive spice. C. sativus dried red stigmas, called threads, are used for culinary, cosmetic, and medicinal purposes. The rest of the flower is often discarded, but is now being used in teas, as coloring agents, and fodder. Previous studies have attributed antioxidant, anti-inflammatory, hepatoprotective, neuroprotective, anti-depressant, and anticancer properties to C. sativus floral bio-residues. The aim of this study is to assess C. sativus flower water extract (CFWE) for its effects on hemoglobin, brush boarder membrane (BBM) functionality, morphology, intestinal gene expression, and cecal microbiome in vivo (Gallus gallus), a clinically validated model. For this, Gallus gallus eggs were divided into six treatment groups (non-injected, 18 Ω H₂O, 1% CFWE, 2% CFWE, 5% CFWE, and 10% CFWE) with n~10 for each group. On day 17 of incubation, 1 mL of the extracts/control were administered in the amnion of the eggs. The amniotic fluid along with the administered extracts are orally consumed by the developing embryo over the course of the next few days. On day 21, the hatchlings were euthanized, the blood, duodenum, and cecum were harvested for assessment. The results showed a significant dose-dependent decrease in hemoglobin concentration, villus surface area, goblet cell number, and diameter. Furthermore, we observed a significant increase in Paneth cell number and Mucin 2 (MUC2) gene expression proportional to the increase in CFWE concentration. Additionally, the cecum microbiome analysis revealed C. sativus flower water extract altered the bacterial populations. There was a significant dose-dependent reduction in Lactobacillus and Clostridium sp., suggesting an antibacterial effect of the extract on the gut in the given model. These results suggest that the dietary consumption of C. sativus flower may have negative effects on BBM functionality, morphology, mineral absorption, microbial populations, and iron status.

Redefining Bean Iron Biofortification: A Review of the Evidence for Moving to a High Fe Bioavailability Approach

Iron biofortification of the common bean (Phaseolus vulgaris) commenced in earnest ~18 years ago. Based on knowledge at the time, the biofortification approach for beans was simply to breed for increased Fe concentration based on 3 major assumptions: (1) The average bean Fe concentration is ~50 μg/g; (2) Higher Fe concentration results in more bioavailable Fe delivered for absorption; (3) Breeding for high Fe concentration is a trait that can be achieved through traditional breeding and is sustainable once a high Fe bean sample is released to farmers. Current research indicates that the assumptions of the high Fe breeding approach are not met in countries of East Africa, a major focus area of bean Fe biofortification. Thus, there is a need to redefine bean Fe biofortification. For assumption 1, recent research indicates that the average bean Fe concentration in East Africa is 71 μg/g, thus about 20 μg/g higher than the assumed value. For assumption 2, recent studies demonstrate that for beans higher Fe concentration does not always equate to more Fe absorption. Finally, for assumption 3, studies show a strong environment and genotype by environment effect on Fe concentration, thus making it difficult to develop and sustain high Fe concentrations. This paper provides an examination of the available evidence related to the above assumptions, and offers an alternative approach utilizing tools that focus on Fe bioavailability to redefine Fe biofortification of the common bean.

Investigation of Genotype by Environment Interactions for Seed Zinc and Iron Concentration and Iron Bioavailability in Common Bean

Iron and zinc malnutrition are global public health concerns afflicting mostly infants, children, and women in low- and middle-income countries with widespread consumption of plant-based diets. Common bean is a widely consumed staple crop around the world and is an excellent source of protein, fiber, and minerals including iron and zinc. The development of nutrient-dense common bean varieties that deliver more bioavailable iron and zinc with a high level of trait stability requires a measurement of the contributions from genotype, environment, and genotype by environment interactions. In this research, we investigated the magnitude of genotype by environment interaction for seed zinc and iron concentration and seed iron bioavailability (FeBIO) using a set of nine test genotypes and three farmers' local check varieties. The research germplasm was evaluated for two field seasons across nine on-farm locations in three agro-ecological zones in Uganda. Seed zinc concentration ranged from 18.0 to 42.0 μg g^-1 and was largely controlled by genotype, location, and the interaction between location and season [28.0, 26.2, and 14.7% of phenotypic variability explained (PVE), respectively]. Within a genotype, zinc concentration ranged on average 12 μg g^-1 across environments. Seed iron concentration varied from 40.7 to 96.7 μg g^-1 and was largely controlled by genotype, location, and the interaction between genotype, location, and season (25.7, 17.4, and 13.7% of PVE, respectively). Within a genotype, iron concentration ranged on average 28 μg g^-1 across environments. Seed FeBIO ranged from 8 to 116% of Merlin navy control and was largely controlled by genotype (68.3% of PVE). The red mottled genotypes (Rozi Koko and Chijar) accumulated the most seed zinc and iron concentration, while the yellow (Ervilha and Cebo Cela) and white (Blanco Fanesquero) genotypes had the highest seed FeBIO and performed better than the three farmers' local check genotypes (NABE-4, NABE-15, and Masindi yellow). The genotypes with superior and stable trait performance, especially the Manteca seed class which combine high iron and zinc concentrations with high FeBIO, would serve as valuable parental materials for crop improvement breeding programs aimed at enhancing the nutritional value of the common bean.

Effects of Iron and Zinc Biofortified Foods on Gut Microbiota In Vivo (Gallus gallus): A Systematic Review

Dietary iron and zinc deficiencies are a global health concern. Bacteria that colonize the gastrointestinal tract depend on minerals to maintain their activities; thus, recent evidence suggests that biofortified foods can modulate the host’s beneficial bacterial taxa. The current review analyzed the research data that linked between iron and zinc biofortified foods and gut microbiota modulation. The data analysis was based on the PRISMA guidelines and the data search was performed at PubMed, Web of Science, Science Direct, and Scopus databases for experimental studies published from January 2010 until December 2020. The five selected studies were conducted in an experimental in vivo model (Gallus gallus). The identified and discussed research showed positive effects of biofortified foods on the composition and function of the gut microbiota. Further, an increase in short chain fatty acids producing bacterial populations as Lactobacillus and Ruminococcus, and a decrease in potentially pathogenic bacteria as Streptococcus, Escherichia, and Enterobacter was identified due to the consumption of biofortified foods. In conclusion, biofortified foods may contribute to improved gut health without increasing the colonization of pathogenic bacteria. The dietary inclusion of approximately 50% of iron/zinc biofortified foods has a significant beneficial effect on the gut microbiota. Additional studies in humans and animal models are warranted to further establish the suggested effects on the intestinal microbiome. PROSPERO (CRD42020184221).

Iron- and Zinc-Fortified Lentil (Lens culinaris Medik.) Demonstrate Enhanced and Stable Iron Bioavailability After Storage

Lentil (Lens culinaris Medik.) is a quick-cooking, rapidly expanding protein-rich crop with high iron (Fe) and zinc (Zn), but low bioavailability due to the presence of phytate, similar to other grains. Lentils dual fortified with Fe and Zn can significantly improve the bioavailable Fe and Zn content. Three milled lentil product types (LPTs) were fortified with Fe using NaFeEDTA [ethylenediaminetetraacetic acid iron (III) sodium salt] (Fe fortified) or Zn from ZnSO₄·H₂O (Zn fortified), or both (dual fortified). Fe, Zn, phytic acid (PA) concentration, and relative Fe bioavailability (RFeB%) were assessed for samples from two fortified batches (initial and for 1 year stored). Fe, Zn, and RFeB% increased significantly in two batches of samples from the three LPTs, and decreased by 5–15% after 1 year of storage. PA concentration decreased from 8 to 15% after fortification of all samples from two batches of the three LPTs but showed different patterns of influence after storage. Dual-fortified lentil fortified with 24 mg Fe and 12 mg Zn 100 g⁻¹ lentil had the highest amount of Fe and Zn, and the lowest PA concentration, and RFeB% was increased from 91.3 to 519.5%. Significant (p ≤ 0.01) Pearson correlations were observed between Fe concentration vs. PA:Fe molar ratio (MR), Fe concentration vs. RFeB%, RFeB% vs. PA:Fe MR, and Zn concentration vs. PA:Zn MR in all samples from two batches of the three LPTs. In conclusion, dual-fortified lentil can contribute significant bioavailable Fe and Zn to populations at risk of Fe and Zn deficiency.

Iron Concentrations in Biofortified Beans and Nonbiofortified Marketplace Varieties in East Africa Are Similar

BACKGROUND

The predominant bean iron (Fe) biofortification approach is to breed for high Fe concentration and assumes the average Fe concentration is 50 μg/g. This approach also assumes that a 40 μg/g increase is sustainable and Fe bioavailability will not decrease to negate the increase in Fe.

OBJECTIVE

The overall objective was to determine if bean Fe biofortification via breeding for high Fe is producing beans with higher Fe concentration relative to nonbiofortified lines found in the East Africa marketplace.

METHODS

Seventy-six marketplace samples (East Africa Marketplace Collection; EAMC), and 154 genotypes known to be representative of the marketplace were collected from breeders in the Pan-Africa Bean Research Alliance (designated the East Africa Breeder Collection; EABC). Within the EAMC and EABC were 18 and 35 samples, respectively, that were released as biofortified lines. All samples were measured for Fe concentration. The Caco-2 cell bioassay assessed Fe bioavailability of the EAMC. Biofortified versus nonbiofortified samples were compared by the appropriate t-test or ANOVA.

RESULTS

The Fe concentration of the 58 nonbiofortified EAMC lines was (mean ± SD [range]) 71 ± 9 μg/g (52-93 μg/g) which did not differ significantly from the 18 biofortified EAMC varieties (71 ± 11 μg/g [55-94 μg/g]). The Fe concentration of the 119 nonbiofortified EABC varieties was 66 ± 7 μg/g (51-90 μg/g) which was significantly different (P < 0.0001) from the 35 EABC biofortified lines (73 ± 9 μg/g [60-91 μg/g]). However, the EABC biofortified lines were not different from the nonbiofortified EAMC samples. In the Caco-2 cell bioassay, biofortified EAMC varieties did not deliver more Fe compared with nonbiofortified EAMC varieties.

CONCLUSIONS

The assumptions of the high Fe bean biofortification approach are not met in the East African marketplace. Iron concentration and bioavailability measurement indicate the biofortified bean varieties are providing no additional dietary Fe.

Low Phytate Peas (Pisum sativum L.) Improve Iron Status, Gut Microbiome, and Brush Border Membrane Functionality In Vivo (Gallus gallus)

The inclusion of pulses in traditional wheat-based food products is increasing as the food industry and consumers are recognizing the nutritional benefits due to the high protein, antioxidant activity, and good source of dietary fiber of pulses. Iron deficiency is a significant global health challenge, affecting approximately 30% of the world's population. Dietary iron deficiency is the foremost cause of anemia, a condition that harms cognitive development and increases maternal and infant mortality. This study intended to demonstrate the potential efficacy of low-phytate biofortified pea varieties on dietary iron (Fe) bioavailability, as well as on intestinal microbiome, energetic status, and brush border membrane (BBM) functionality in vivo (Gallus gallus). We hypothesized that the low-phytate biofortified peas would significantly improve Fe bioavailability, BBM functionality, and the prevalence of beneficial bacterial populations. A six-week efficacy feeding (n = 12) was conducted to compare four low-phytate biofortified pea diets with control pea diet (CDC Bronco), as well as a no-pea diet. During the feeding trial, hemoglobin (Hb), body-Hb Fe, feed intake, and body weight were monitored. Upon the completion of the study, hepatic Fe and ferritin, pectoral glycogen, duodenal gene expression, and cecum bacterial population analyses were conducted. The results indicated that certain low-phytate pea varieties provided greater Fe bioavailability and moderately improved Fe status, while they also had significant effects on gut microbiota and duodenal brush border membrane functionality. Our findings provide further evidence that the low-phytate pea varieties appear to improve Fe physiological status and gut microbiota in vivo, and they highlight the likelihood that this strategy can further improve the efficacy and safety of the crop biofortification and mineral bioavailability approach.

Special bioactive compounds and functional foods may exhibit neuroprotective effects in patients with dementia (Review)

Dementia is a failure of cognitive ability characterized by severe neurodegeneration in select neural systems, and Alzheimer's disease (AD) is the most common type of neurodegenerative disease. Although numerous studies have provided insights into the pathogenesis of AD, the underlying signaling and molecular pathways mediating the progressive decline of cognitive function remain poorly understood. Recent progress in molecular biology has provided an improved understanding of the importance of molecular pathogenesis of AD, and has proposed an association between DNA repair mechanisms and AD. In particular, the fundamental roles of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and breast cancer gene 1 (BRCA1) tumor suppressors have been shown to regulate the pathogenesis of neurodegeneration. Consequently, onset of neurodegenerative diseases may be deferred with the use of dietary neuroprotective agents which alter the signaling mediated by the aforementioned tumor suppressors. In a healthy neuron, homeostasis of key intracellular molecules is of great importance, and preventing neuronal apoptosis is one of the primary goals of treatments designed for dementia-associated diseases. In the present review, progress into the understanding of dietary regulation for preventing or limiting development of dementia is discussed with a focus on the modulatory roles of PTEN and BRCA1 signaling.

Iron, Zinc and Phytic Acid Retention of Biofortified, Low Phytic Acid, and Conventional Bean Varieties When Preparing Common Household Recipes

Biofortification is an effective method to improve the nutritional content of crops and nutritional intake. Breeding for higher micronutrient mineral content in beans is correlated with an increase in phytic acid, a main inhibitor of mineral absorption in humans. Low phytic acid (lpa) beans have a 90% lower phytic acid content compared to conventional beans. This is the first study to investigate mineral and total phytic acid retention after preparing common household recipes from conventional, biofortified and lpa beans. Mineral retention was determined for two conventional, three biofortified and two lpa bean genotypes. Treatments included soaking, boiling (boiled beans) and refrying (bean paste). The average true retention of iron after boiling was 77.2-91.3%; for zinc 41.2-84.0%; and for phytic acid 49.9-85.9%. Soaking led to a significant decrease in zinc and total phytic acid after boiling and refrying, whereas for iron no significant differences were found. lpa beans did not exhibit a consistent pattern of difference in iron and phytic acid retention compared to the other groups of beans. However, lpa beans had a significantly lower retention of zinc compared to conventional and biofortified varieties (p < 0.05). More research is needed to understand the underlying factors responsible for the differences in retention between the groups of beans, especially the low retention of zinc. Combining the lpa and biofortification traits could further improve the nutritional benefits of biofortified beans, by decreasing the phytic acid:iron and zinc ratio in beans.

Nicotianamine-chelated iron positively affects iron status, intestinal morphology and microbial populations in vivo (Gallus gallus)

Wheat flour iron (Fe) fortification is mandatory in 75 countries worldwide yet many Fe fortificants, such as Fe-ethylenediaminetetraacetate (EDTA), result in unwanted sensory properties and/or gastrointestinal dysfunction and dysbiosis. Nicotianamine (NA) is a natural chelator of Fe, zinc (Zn) and other metals in higher plants and NA-chelated Fe is highly bioavailable in vitro. In graminaceous plants NA serves as the biosynthetic precursor to 2' -deoxymugineic acid (DMA), a related Fe chelator and enhancer of Fe bioavailability, and increased NA/DMA biosynthesis has proved an effective Fe biofortification strategy in several cereal crops. Here we utilized the chicken (Gallus gallus) model to investigate impacts of NA-chelated Fe on Fe status and gastrointestinal health when delivered to chickens through intraamniotic administration (short-term exposure) or over a period of six weeks as part of a biofortified wheat diet containing increased NA, Fe, Zn and DMA (long-term exposure). Striking similarities in host Fe status, intestinal functionality and gut microbiome were observed between the short-term and long-term treatments, suggesting that the effects were largely if not entirely due to consumption of NA-chelated Fe. These results provide strong support for wheat with increased NA-chelated Fe as an effective biofortification strategy and uncover novel impacts of NA-chelated Fe on gastrointestinal health and functionality.

Bioaccessibility and bioavailability of iron in biofortified germinated cowpea

BACKGROUND

Cowpea (Vigna unguiculata L. Walph) is predominantly consumed in the North and Northeast regions of Brazil, and its biofortification with iron seeks to reduce the high prevalence of iron deficiency anemia in these regions. It is commonly eaten cooked; however, in the germinated form, it can improve nutritional quality by reducing the antinutritional factors and consequently improving the bioavailability of elements. The present study aimed to determine the physico-chemical characteristics, bioaccessibility and bioavailability of iron in biofortified germinated cowpea.

RESULTS

There was no statistical difference between the germinated and cooked beans with regard to centesimal composition. Germinated beans had phytates and tannins similar to cooked beans. The phytate-iron molar ratio for all groups did not present a statistical difference (cooking 3.58 and 3.41; germinated 3.94 and 3.51), nor did the parameters evaluating in vivo iron bioavailability. Total phenolics was higher in the germinated group (cooking 0.56 and 0.64; Germinated 2.05 and 2.45 mg gallic acid kg^-1 ). In vitro bioaccessibility of iron of germinated beans presented higher values (P ≤ 0.05) compared to cooked beans. There was higher expression of divalent metal transporter-1 in biofortified and germinated beans.

CONCLUSION

The iron bioavailability from the biofortified and germinated beans was comparable to ferrous sulfate. Germination can be considered as an alternative and efficient method for consuming cowpea, presenting good iron bioaccessibility and bioavailability. © 2019 Society of Chemical Industry.

Metabolic engineering of bread wheat improves grain iron concentration and bioavailability

Bread wheat (Triticum aestivum L.) is cultivated on more land than any other crop and produces a fifth of the calories consumed by humans. Wheat endosperm is rich in starch yet contains low concentrations of dietary iron (Fe) and zinc (Zn). Biofortification is a micronutrient intervention aimed at increasing the density and bioavailability of essential vitamins and minerals in staple crops; Fe biofortification of wheat has proved challenging. In this study we employed constitutive expression (CE) of the rice (Oryza sativa L.) nicotianamine synthase 2 (OsNAS2) gene in bread wheat to up-regulate biosynthesis of two low molecular weight metal chelators - nicotianamine (NA) and 2'-deoxymugineic acid (DMA) - that play key roles in metal transport and nutrition. The CE-OsNAS2 plants accumulated higher concentrations of grain Fe, Zn, NA and DMA and synchrotron X-ray fluorescence microscopy (XFM) revealed enhanced localization of Fe and Zn in endosperm and crease tissues, respectively. Iron bioavailability was increased in white flour milled from field-grown CE-OsNAS2 grain and positively correlated with NA and DMA concentrations.

An In Vivo (Gallus gallus) Feeding Trial Demonstrating the Enhanced Iron Bioavailability Properties of the Fast Cooking Manteca Yellow Bean (Phaseolus vulgaris L.)

The common dry bean (Phaseolus vulgaris L.) is a globally produced pulse crop and an important source of micronutrients for millions of people across Latin America and Africa. Many of the preferred black and red seed types in these regions have seed coat polyphenols that inhibit the absorption of iron. Yellow beans are distinct from other market classes because they accumulate the antioxidant kaempferol 3-glucoside in their seed coats. Due to their fast cooking tendencies, yellow beans are often marketed at premium prices in the same geographical regions where dietary iron deficiency is a major health concern. Hence, this study compared the iron bioavailability of three faster cooking yellow beans with contrasting seed coat colors from Africa (Manteca, Amarillo, and Njano) to slower cooking white and red kidney commercial varieties. Iron status and iron bioavailability was assessed by the capacity of a bean based diet to generate and maintain total body hemoglobin iron (Hb-Fe) during a 6 week in vivo (Gallus gallus) feeding trial. Over the course of the experiment, animals fed yellow bean diets had significantly (p ≤ 0.05) higher Hb-Fe than animals fed the white or red kidney bean diet. This study shows that the Manteca yellow bean possess a rare combination of biochemical traits that result in faster cooking times and improved iron bioavailability. The Manteca yellow bean is worthy of germplasm enhancement to address iron deficiency in regions where beans are consumed as a dietary staple.

Investigation of Nicotianamine and 2' Deoxymugineic Acid as Enhancers of Iron Bioavailability in Caco-2 Cells

Nicotianamine (NA) is a low-molecular weight metal chelator in plants with high affinity for ferrous iron (Fe2+) and other divalent metal cations. In graminaceous plant species, NA serves as the biosynthetic precursor to 2' deoxymugineic acid (DMA), a root-secreted mugineic acid family phytosiderophore that chelates ferric iron (Fe3+) in the rhizosphere for subsequent uptake by the plant. Previous studies have flagged NA and/or DMA as enhancers of Fe bioavailability in cereal grain although the extent of this promotion has not been quantified. In this study, we utilized the Caco-2 cell system to compare NA and DMA to two known enhancers of Fe bioavailability-epicatechin (Epi) and ascorbic acid (AsA)-and found that both NA and DMA are stronger enhancers of Fe bioavailability than Epi, and NA is a stronger enhancer of Fe bioavailability than AsA. Furthermore, NA reversed Fe uptake inhibition by Myricetin (Myr) more than Epi, highlighting NA as an important target for biofortification strategies aimed at improving Fe bioavailability in staple plant foods.

The Germ Fraction Inhibits Iron Bioavailability of Maize: Identification of an Approach to Enhance Maize Nutritional Quality via Processing and Breeding

Improving the nutritional quality of Fe in maize (Zea mays) represents a biofortification strategy to alleviate iron deficiency anemia. Therefore, the present study measured iron content and bioavailability via an established bioassay to characterize Fe quality in parts of the maize kernel. Comparisons of six different varieties of maize demonstrated that the germ fraction is a strong inhibitory component of Fe bioavailability. The germ fraction can contain 27-54% of the total kernel Fe, which is poorly available. In the absence of the germ, Fe in the non-germ components can be highly bioavailable. More specifically, increasing Fe concentration in the non-germ fraction resulted in more bioavailable Fe. Comparison of wet-milled fractions of a commercial maize variety and degerminated corn meal products also demonstrated the inhibitory effect of the germ fraction on Fe bioavailability. When compared to beans (Phaseolus vulgaris) containing approximately five times the concentration of Fe, degerminated maize provided more absorbable Fe, indicating substantially higher fractional bioavailability. Overall, the results indicate that degerminated maize may be a better source of Fe than whole maize and some other crops. Increased non-germ Fe density with a weaker inhibitory effect of the germ fraction are desirable qualities to identify and breed for in maize.

Alterations in gut microflora populations and brush border functionality following intra-amniotic administration (Gallus gallus) of wheat bran prebiotic extracts

Wheat bran is the by-product of milling wheat flour which is one of the richest sources of dietary fiber, and cellulase that can be used for increasing the soluble dietary fiber.

Iron Biofortified Carioca Bean (Phaseolus vulgaris L.)-Based Brazilian Diet Delivers More Absorbable Iron and Affects the Gut Microbiota In Vivo (Gallus gallus)

Biofortification aims to improve the micronutrient concentration and bioavailability in staple food crops. Unlike other strategies utilized to alleviate Fe deficiency, studies of the gut microbiota in the context of Fe biofortification are scarce. In this study, we performed a 6-week feeding trial in Gallus gallus (n = 15), aimed to investigate the Fe status and the alterations in the gut microbiome following the administration of Fe-biofortified carioca bean based diet (BC) versus a Fe-standard carioca bean based diet (SC). The tested diets were designed based on the Brazilian food consumption survey. Two primary outcomes were observed: (1) a significant increase in total body Hb-Fe values in the group receiving the Fe-biofortified carioca bean based diet; and (2) changes in the gut microbiome composition and function were observed, specifically, significant changes in phylogenetic diversity between treatment groups, as there was increased abundance of bacteria linked to phenolic catabolism, and increased abundance of beneficial SCFA-producing bacteria in the BC group. The BC group also presented a higher intestinal villi height compared to the SC group. Our results demonstrate that the Fe-biofortified carioca bean variety was able to moderately improve Fe status and to positively affect the intestinal functionality and bacterial populations.

Reduction in nutritional quality and growing area suitability of common bean under climate change induced drought stress in Africa

Climate change impacts on food security will involve negative impacts on crop yields, and potentially on the nutritional quality of staple crops. Common bean is the most important grain legume staple crop for human diets and nutrition worldwide. We demonstrate by crop modeling that the majority of current common bean growing areas in southeastern Africa will become unsuitable for bean cultivation by the year 2050. We further demonstrate reductions in yields of available common bean varieties in a field trial that is a climate analogue site for future predicted drought conditions. Little is known regarding the impact of climate change induced abiotic stresses on the nutritional quality of common beans. Our analysis of nutritional and antinutritional compounds reveals that iron levels in common bean grains are reduced under future climate-scenario relevant drought stress conditions. In contrast, the levels of protein, zinc, lead and phytic acid increase in the beans under such drought stress conditions. This indicates that under climate-change induced drought scenarios, future bean servings by 2050 will likely have lower nutritional quality, posing challenges for ongoing climate-proofing of bean production for yields, nutritional quality, human health, and food security.

Reduction in nutritional quality and growing area suitability of common bean under climate change induced drought stress in Africa

Climate change impacts on food security will involve negative impacts on crop yields, and potentially on the nutritional quality of staple crops. Common bean is the most important grain legume staple crop for human diets and nutrition worldwide. We demonstrate by crop modeling that the majority of current common bean growing areas in southeastern Africa will become unsuitable for bean cultivation by the year 2050. We further demonstrate reductions in yields of available common bean varieties in a field trial that is a climate analogue site for future predicted drought conditions. Little is known regarding the impact of climate change induced abiotic stresses on the nutritional quality of common beans. Our analysis of nutritional and antinutritional compounds reveals that iron levels in common bean grains are reduced under future climate-scenario relevant drought stress conditions. In contrast, the levels of protein, zinc, lead and phytic acid increase in the beans under such drought stress conditions. This indicates that under climate-change induced drought scenarios, future bean servings by 2050 will likely have lower nutritional quality, posing challenges for ongoing climate-proofing of bean production for yields, nutritional quality, human health, and food security.

Relative Bioavailability of Iron in Bangladeshi Traditional Meals Prepared with Iron-Fortified Lentil Dal

Due to low Fe bioavailability and low consumption per meal, lentil must be fortified to contribute significant bioavailable Fe in the Bangladeshi diet. Moreover, since red lentil is dehulled prior to consumption, an opportunity exists at this point to fortify lentil with Fe. Thus, in the present study, lentil was Fe-fortified (using a fortificant Fe concentration of 2800 µg g⁻¹) and used in 30 traditional Bangladeshi meals with broad differences in concentrations of iron, phytic acid (PA), and relative Fe bioavailability (RFeB%). Fortification with NaFeEDTA increased the iron concentration in lentil from 60 to 439 µg g⁻¹ and resulted in a 79% increase in the amount of available Fe as estimated by Caco-2 cell ferritin formation. Phytic acid levels were reduced from 6.2 to 4.6 mg g⁻¹ when fortified lentil was added, thereby reducing the PA:Fe molar ratio from 8.8 to 0.9. This effect was presumably due to dephytinization of fortified lentil during the fortification process. A significant (p ≤ 0.01) Pearson correlation was observed between Fe concentration and RFeB% and between RFeB% and PA:Fe molar ratio in meals with fortified lentil, but not for the meal with unfortified lentil. In conclusion, fortified lentil can contribute significant bioavailable Fe to populations at risk of Fe deficiency.

Linoleic Acid:Dihomo-γ-Linolenic Acid Ratio Predicts the Efficacy of Zn-Biofortified Wheat in Chicken (Gallus gallus)

The amount of Zn absorbed from Zn-biofortified wheat material has been determined using an in vivo model of Zn absorption. The erythrocyte linoleic:dihomo -γ-linolenic acid (LA:DGLA) ratio was used as a biomarker of Zn status. Two groups of chickens (n = 15) were fed different diets: a high-Zn (46.5 μg Zn g^-1) and a low-Zn wheat-based diet (32.8 μg Zn g^-1). Dietary Zn intakes, body weight, serum Zn, and the erythrocyte fatty acid profile were measured, and tissues were taken for gene expression analysis. Serum Zn concentrations were greater in the high Zn group (p < 0.05). Duodenal mRNA expression of various Zn transporters demonstrated expression upregulation in the birds fed a low Zn diet (n = 15, p < 0.05). The LA:DGLA ratio was higher in the birds fed the low Zn diet (p < 0.05). The higher amount of Zn in the biofortified wheat resulted in a greater Zn uptake.

Characterizing the gut (Gallus gallus) microbiota following the consumption of an iron biofortified Rwandan cream seeded carioca (Phaseolus Vulgaris L.) bean-based diet

Biofortification is a plant breeding method that introduces increased concentrations of minerals in staple food crops (e.g., legumes, cereal grains), and has shown success in alleviating insufficient Fe intake in various human populations. Unlike other strategies utilized to alleviate Fe deficiency, studies of the gut microbiota in the context of Fe biofortification have not yet been reported, although the consumption of Fe biofortified staple food crops has increased significantly over time. Hence, in this study, we performed a 6-week feeding trial in Gallus gallus (n = 14), aimed to investigate the alterations in the gut microbiome following administration of an Fe biofortified bean-based diet (biofortified, BFe) versus a bean based diet with poorly-bioavailable Fe (standard, SFe). Cream seeded carioca bean based diets were designed in an identical fashion to those used in a recent human clinical trial of Fe biofortified beans in Rwanda. We hypothesized that the different dietary Fe contents in the beans based diets will alter the composition and function of the intestinal microbiome. The primary outcomes were changes in the gut microbiome composition and function analyzed by 16S rRNA gene sequencing. We observed no significant changes in phylogenetic diversity between groups. There were significant differences in the composition of the microbiota between groups, with the BFe group harboring fewer taxa participating in bacterial Fe uptake, increased abundance of bacteria involved in phenolic catabolism, and increased abundance of beneficial butyrate-producing bacteria. Additionally, depletion of key bacterial pathways responsible for bacterial viability and Fe uptake suggest that improvements in Fe bioavailability, in addition to increases in Fe-polyphenol and Fe-phytate complexes due to biofortification, led to decreased concentrations of cecal Fe available for bacterial utilization. Our findings demonstrate that Fe biofortification may improve Fe status without negatively altering the structure and function of the gut microbiota, as is observed with other nutritional methods of Fe supplementation. These results may be used to further improve the efficacy and safety of future biofortification efforts in eradicating global Fe deficiency.

Biomimetic Gastrointestinal Tract Functions for Metal Absorption Assessment in Edible Plants: Comparison to In Vivo Absorption

A biomimetic gastrointestinal tract, including in vitro digestion and biomimetic biomembrane extraction, has been proposed for absorption assessment of metals from edible plants. However, its validity is still unknown. Herein, two species of edible plants, Anoectochilus roxburghii and Radix astragali, were selected and digested in a bionic mouth, stomach, and intestine, and then trace metals (Cr, Mn, Fe, Ni, Cu, Zn, Se, Sr, As, and Pb) were transformed to their final metal species. To check model predictability, in vitro and in vivo metal absorption were imitated and tested by monolayer liposome extraction and rat stomach or single-pass duodenal intestine, respectively. A strong correlation was established between in vivo and in vitro metal absorption ratios, with 0.89 > R² > 0.66, and a significant relationship (p < 0.05) was exhibited for stomach, intestine, two plant species, and 10 metal species. Our biomimetic system could be used as low-cost alternatives to animal and clinical studies for multi-metal absorption.

Nutrient and Total Polyphenol Contents of Dark Green Leafy Vegetables, and Estimation of Their Iron Bioaccessibility Using the In Vitro Digestion/Caco-2 Cell Model

Dark green leafy vegetables (DGLVs) are considered as important sources of iron and vitamin A. However, iron concentration may not indicate bioaccessibility. The objectives of this study were to compare the nutrient content and iron bioaccessibility of five sweet potato cultivars, including three orange-fleshed types, with other commonly consumed DGLVs in Ghana: cocoyam, corchorus, baobab, kenaf and moringa, using the in vitro digestion/Caco-2 cell model. Moringa had the highest numbers of iron absorption enhancers on an “as-would-be-eaten” basis, β-carotene (14169 μg/100 g; p < 0.05) and ascorbic acid (46.30 mg/100 g; p < 0.001), and the best iron bioaccessibility (10.28 ng ferritin/mg protein). Baobab and an orange-fleshed sweet potato with purplish young leaves had a lower iron bioaccessibility (6.51 and 6.76 ng ferritin/mg protein, respectively) compared with that of moringa, although these three greens contained similar (p > 0.05) iron (averaging 4.18 mg/100 g) and β-carotene levels. The ascorbic acid concentration of 25.50 mg/100 g in the cooked baobab did not enhance the iron bioaccessibility. Baobab and the orange-fleshed sweet potato with purplish young leaves contained the highest levels of total polyphenols (1646.75 and 506.95 mg Gallic Acid Equivalents/100 g, respectively; p < 0.001). This suggests that iron bioaccessibility in greens cannot be inferred based on the mineral concentration. Based on the similarity of the iron bioaccessibility of the sweet potato leaves and cocoyam leaf (a widely-promoted “nutritious” DGLV in Ghana), the former greens have an added advantage of increasing the dietary intake of provitamin A.

Intra-Amniotic Administration (Gallus gallus) of Cicer arietinum and Lens culinaris Prebiotics Extracts and Duck Egg White Peptides Affects Calcium Status and Intestinal Functionality

Calcium (Ca) is one of the most abundant inorganic elements in the human body and has many important physiological roles. Prebiotics and bioactive peptides are two important substances used to promote calcium uptake. However, the difference in mechanisms of the calcium uptake from these two supplements is not clear. By using the Gallus gallus model and the intra-amniotic administration procedure, the aim of this study was to investigate whether Ca status, intestinal functionality, and health-promoting bacterial populations were affected by prebiotics extracted from chickpea and lentil, and duck egg white peptides (DPs). Eleven groups (non-injected; 18 MΩ H₂O; 4 mmol/L CaCl₂; 50 mg/mL chickpea + 4 mmol/L CaCl₂; 50 mg/mL lentil + 4 mmol/L CaCl₂; 40 mg/mL DPs + 4 mmol/L CaCl₂; 5 mg/mL Val-Ser-Glu-Glu (VSEE) + 4 mmol/L CaCl₂; 50 mg/mL chickpea; 50 mg/mL lentil; 40 mg/mL DPs; 5 mg/mL VSEE) were utilized. Upon hatch, blood, cecum, small intestine, liver and bone were collected for assessment of serum bone alkaline phosphate level (BALP), the relative abundance of intestinal microflora, expression of Ca-related genes, brush border membrane (BBM) functional genes, and liver and bone mineral levels, respectively. The BALP level increased in the presence of lentil, DPs and VSEE (p < 0.05). The relative abundance of probiotics increased significantly (p < 0.05) by VSEE + Ca and chickpea. The expression of CalbindinD9k (Ca transporter) increased (p < 0.05) in Ca, chickpea + Ca and lentil + Ca groups. In addition, the brush border membrane functionality genes expressions increased (p < 0.05) by the chickpea or lentil extracts. Prebiotics and DPs beneficially affected the intestinal microflora and duodenal villus surface area. This research expands the understanding of the prebiotics’ properties of chickpea and lentil extracts, and peptides’ effects on calcium metabolism and gut health.

Iron Bioavailability Studies of the First Generation of Iron-Biofortified Beans Released in Rwanda

This paper represents a series of in vitro iron (Fe) bioavailability experiments, Fe content analysis and polyphenolic profile of the first generation of Fe biofortified beans (Phaseolus vulgaris) selected for human trials in Rwanda and released to farmers of that region. The objective of the present study was to demonstrate how the Caco-2 cell bioassay for Fe bioavailability can be utilized to assess the nutritional quality of Fe in such varieties and how they may interact with diets and meal plans of experimental studies. Furthermore, experiments were also conducted to directly compare this in vitro approach with specific human absorption studies of these Fe biofortified beans. The results show that other foods consumed with beans, such as rice, can negatively affect Fe bioavailability whereas potato may enhance the Fe absorption when consumed with beans. The results also suggest that the extrinsic labelling approach to measuring human Fe absorption can be flawed and thus provide misleading information. Overall, the results provide evidence that the Caco-2 cell bioassay represents an effective approach to evaluate the nutritional quality of Fe-biofortified beans, both separate from and within a targeted diet or meal plan.

Advantages and limitations of in vitro and in vivo methods of iron and zinc bioavailability evaluation in the assessment of biofortification program effectiveness

Biofortification aims to improve the micronutrient concentration of staple food crops through the best practices of breeding and modern biotechnology. However, increased zinc and iron concentrations in food crops may not always translate into proportional increases in absorbed zinc (Zn) and iron (Fe). Therefore, assessing iron and zinc bioavailability in biofortified crops is imperative to evaluate the efficacy of breeding programs. This review aimed to investigate the advantages and limitations of in vitro and in vivo methods of iron and zinc bioavailability evaluation in the assessment of biofortification program effectiveness. In vitro, animal and isotopic human studies have shown high iron and zinc bioavailability in biofortified staple food crops. Human studies provide direct knowledge regarding the effectiveness of biofortification, however, human studies are time consuming and are more expensive than in vitro and animal studies. Moreover, in vitro studies may be a useful preliminary screening method to identify promising plant cultivars, however, these studies cannot provide data that are directly applicable to humans. None of these methods provides complete information regarding mineral bioavailability, thus, a combination of these methods should be the most appropriate strategy to investigate the effectiveness of zinc and iron biofortification programs.

Characterization of Polyphenol Effects on Inhibition and Promotion of Iron Uptake by Caco-2 Cells

Polyphenolic compounds present in the seed coat of common bean (Phaseolus vulgaris L.) are known to act collectively as inhibitors of iron bioavailability. Recent research identified specific polyphenols as being potent Fe uptake inhibitors. That research also identified other polyphenols as being promoters of Fe uptake. The present study extends that work using a Caco-2 cell model to characterize the effects of 43 additional polyphenols on Fe uptake. In addition, this study indicates that the inhibitory compounds have a more potent effect that outweighs the ability of promoting compounds to increase Fe uptake. For example, a ratio of 100:0 epicatechin (a promoter)/myricetin (an inhibitor) produced 78.5 ± 6.7 ng ferritin/mg protein, 90:10 yielded 27.4 ± 3.0, 50:50 yielded 3.42 ± 0.54, and 0:100 yielded 2.26 ± 0.25 ng ferritin/mg protein. A simulation of the relative concentrations of eight major polyphenols (four inhibitors, four promoters) present in a sample of black bean seed coats demonstrated that most of the inhibitory compounds would need to be removed to reduce the negative effect on Fe uptake. In vivo studies are now warranted to confirm the above in vitro effects. Such work would be significant as other bean color classes exist that are likely to have polyphenolic profiles that are more favorable to Fe bioavailability.