Effect of phytate reduction of sorghum, through genetic modification, on iron and zinc availability as assessed by an in vitro dialysability bioaccessibility assay, Caco-2 cell uptake assay, and suckling rat pup absorption model

Proximate composition and anti-nutritional factors in Mucuna pruriens (velvet bean) seed flour as affected by several processing methods

Mucuna pruriens seed being an underutilized legume with antinutrients was processed to reduce antinutrients and improve nutritional quality. The seeds were cleaned, washed and subjected to single treatments of soaking (24 h, 48 h, 72 h), cooking (20 min, 40 min, 60 min, 80 min), roasting (10 min, 15 min, 20 min), germination (24 h, 48 h, 72 h) and fermentation (24 h, 48 h, 72 h). Combined treatments: soaking (72 h) + cooking (60 min); germination (48 h) + roasting (15 min); germination (48 h) + cooking (60 min); fermentation (72 h) + roasting (15 min) were also separately carried out. Proximate composition and antinutrients were evaluated. Crude protein ranged from 25.34 to 29.50%, ash 3.02-3.82% and crude fibre 0.70-4.69. Crude protein was increased by single and double treatments while ash content was increased by only single treatments. All the treatments reduced the crude fibre. For single and double treatments, phenol, L-3,4-dihydroxyphenylalanine and trypsin inhibitor were in the range of 0.69-3.49%, 0.01-6.83% and 0.00-12.58 TIU/mg protein respectively. This research indicated that the use of up to 72 h soaking, 80 min cooking, 20 min roasting, 72 h germination or 72 h fermentation (Rhizopus oligosporus) is not adequate to reduce phenol and L-3,4-dihydroxyphenylalanine in Mucuna pruriens seed flour to below the recommended safe limits of 0.003% and 0.1% respectively. The double treatment of 72 h fermentation +15 m roasting was the only treatment that reduced L-3,4-dihydroxyphenylalanine to safe limit of 0.01%.

Zinc Fortification: Current Trends and Strategies

Zinc, through its structural and cofactor roles, affects a broad range of critical physiological functions, including growth, metabolism, immune and neurological functions. Zinc deficiency is widespread among populations around the world, and it may, therefore, underlie much of the global burden of malnutrition. Current zinc fortification strategies include biofortification and fortification with zinc salts with a primary focus on staple foods, such as wheat or rice and their products. However, zinc fortification presents unique challenges. Due to the influences of phytate and protein on zinc absorption, successful zinc fortification strategies should consider the impact on zinc bioavailability in the whole diet. When zinc is absorbed with food, shifts in plasma zinc concentrations are minor. However, co-absorbing zinc with food may preferentially direct zinc to cellular compartments where zinc-dependent metabolic processes primarily occur. Although the current lack of sensitive biomarkers of zinc nutritional status reduces the capacity to assess the impact of fortifying foods with zinc, new approaches for assessing zinc utilization are increasing. In this article, we review the tools available for assessing bioavailable zinc, approaches for evaluating the zinc nutritional status of populations consuming zinc fortified foods, and recent trends in fortification strategies to increase zinc absorption.

Comparative study of physicochemical, nutritional, phytochemical, and sensory properties of bread with plantain and soy flours partly replacing wheat flour

Plantain flour (PLF) and soy flour (SF) were used to substitute wheat flour (10% and 20% w/w) in composite bread. Physicochemical, phytochemical, and sensory properties were investigated. Partial substitution by PLF significantly increased (p < .05) starch, amylose, ascorbic acid, and potassium content in bread samples. In contrast, a significant improvement (p < .05) in protein, fat, amylopectin, and calcium content was observed with SF substitution. Composite bread with PLF and SF together lowered the hydrolysis index (HI) and glycemic index (GI) as compared with whole wheat flour. The molar phytate to minerals (iron, zinc, and calcium) ratio in all composite loaves was lower than reported critical values, except for phytate to iron. Significant differences (p < .05) were found in color, specific volume, and texture characteristics of loaves made from partial substitution with PLF and SF. Sensory evaluation revealed that bread with 10% PLF exhibited better scores for appearance and willingness to pay than the control. In contrast, SF negatively affected (p < .05) the appearance, texture, color, overall acceptance, and willingness to pay. The trade‐off analysis indicated that PLF can be utilized to produce bread that meets consumers' demands, while incorporating SF as an alternative high‐nutrient density bread will be beneficial to health.

Sorghum polyphenols: plant stress, human health benefits, and industrial applications

MAIN CONCLUSION

Various phenolic compounds of sorghum are effective in the management of abiotic stress (salt, nutrients) and biotic stress (caused by birds, fungi and aphids). The health and industrial application of phenolics is mainly contributed by inherent antioxidant and nutraceutical potential. In a natural environment, plant growth is affected by various biotic and abiotic stresses. In every ecosystem, the presence of a wide range of harmful biological agents (bacteria, fungi, nematodes, mites, and insects) and undesirable environmental factors (drought, salinity, heat, excessive or low rainfall, etc.) may cause a heavy loss in crop productivity. Being sessile during evolution, plants have evolved multiple defense mechanisms against various types of microbial pathogens and environmental stresses. A plant's natural defense system produces some compounds named secondary metabolites, which include phenolics, terpenes, and nitrogen. The phenolic profile of grain sorghum, the least utilized staple crop, is unique, more diverse, and more abundant than in any other common cereal grain. It mainly contains phenolic acids, 3-deoxyanthocyanidins and condensed tannins. Sorghum polyphenols play a major role in plant defense against biotic and abiotic stresses and have many additional health benefits along with various industrial applications. The objective of this review is to discuss the phenolic compounds derived from grain sorghum and describe their role in plant defense, human health, and industrial applications.

Comparison of bioaccessibility and relative bioavailability of arsenic in rice bran: The in vitro with PBET/SHIME and in vivo with mice model

Rice bran, a super food or health food supplement, contains high arsenic (As) levels. However, the evaluation of relative bioavailability (RBA) or bioaccessibility (BA) is limited in the rice bran. In this study, the As-RBA in rice bran was determined based on mice model and compared to As-BA using in vitro methods. The As-BA from rice bran-amended feed in the gastric, small intestinal, and colon phases were 33.1-56.4%, 50.5-75.6%, and 35.5-71.4%, respectively. The As-BA was adversely associated with bioaccessible Ca and Fe concentrations in the gastrointestinal phases. Similarly, the As-RBA was significant negative relative with Ca, Fe, and Zn concentrations. The As-RBA values were 37.9-65.5%, 41.5-75.6% and 38.7-71.5% based on liver, kidneys, and combined endpoint (liver plus kidneys), respectively. The in vitro-in vivo correlations (IVIVCs) in the gastric (R² = 0.392) and colon (R² = 0.362) phases were weak. While the IVIVC (R² = 0.544) in the small intestinal phase was stronger than those of the gastric and colon phases. In addition, there was no significant difference in As speciation between colonic residual solids and faeces (p > 0.05). This work provides a better view of human health risk evaluation on rice bran As consumption in humans.

Potential of food-to-food fortification with cowpea leaves and orange-fleshed sweet potato, in combination with conventional fortification, to improve the cellular uptake of iron and zinc from ready-to-eat maize porridges

An emerging tool in the fight against the high prevalence of micronutrient deficiencies in sub-Saharan Africa is the production of nutritionally enhanced staple food products, through food-to-food fortification with micronutrient-dense fruits and vegetables. This study investigated food-to-food fortification with cowpea leaves (CL) and orange-fleshed sweet potato (OFSP) in combination with conventional micronutrient fortification and fermentation on the mineral and antinutrient contents and Caco-2 cellular uptake of iron and zinc from ready-to-eat maize porridges. The amount of iron and zinc taken up from maize porridges (0.05 and 0.06 mg/100 g, db, respectively) was increased more after fortification with CL, compared to OFSP (0.32 and 0.23 mg/100 g, db versus. 0.11 and 0.04 mg/100 g, db, respectively). Despite the moderate cellular uptakes of iron and zinc from the CL fortified porridges (2.71% and 3.10%, respectively) compared to the OFSP fortified porridges (6.51% and 5.22%, respectively), the CL fortified porridges had much higher high iron and zinc contents (12.2-14.1 and 7.6-8.9 mg/100 g, db versus. 2.1-3.7 and 1.5-2.7 mg/100 g, db, respectively). This highlights the importance of increasing both the mineral content and bioavailability when fortifying a product. Even when a food product contains substantial antinutrients such as CL, if the mineral content and contents of bioavailability enhancers are high enough, the amounts of bioavailable iron and zinc can still be improved.

Fermentability and nutritional characteristics of sorghum Mahewu supplemented with Bambara groundnut

Processing functionality in terms of fermentability and nutritional characteristics of Mahewu (a sorghum-based nonalcoholic beverage product) supplemented with different proportions of Bambara groundnut (BGN) (80:20 and 70:30, respectively) was investigated to develop a sorghum-based beverage product with improved nutritional quality. Sorghum-BGN Mahewu blends showed a rapid reduction in pH and significantly (P < 0.05) lower final pH (4.3) after 24 hr compared to the control (pH 5.1) (100% Sorghum Mahewu). With total titratable acidity (TTA), sorghum-BGN Mahewu blends had significantly higher final TTA (0.7%) than control (0.4%). Sorghum-BGN Mahewu blends had higher protein and crude fiber contents (up to 7.7% and 7.9%, respectively) than control (6.1% and 5.7%, respectively). In general, sorghum Mahewu supplemented with BGN did not show substantial increase in mineral and individual amino acid contents after fermentation compared to the control, possibly due to increase in tannin content with BGN supplementation. Fermentation significantly (P < 0.05) reduced phytate content by more than 90% in sorghum Mahewu supplemented with BGN when compared to the control (28% reduction). Importantly, BGN supplementation improved the level of some essential amino acids such as threonine, methionine, phenylalanine, isoleucine, leucine, histidine, and lysine. Therefore, supplementation with BGN can potentially improve the nutritional quality of sorghum Mahewu but modification in processing procedure is required to effectively improve the nutritional quality of sorghum-BGN blends. PRACTICAL APPLICATION: This research work has direct application in addressing problem of malnutrition, as well as improving utilization of indigenous food crops in commercial food processing. This is one of the practical approach to address food insecurity that is prevalent in most African countries.

In Vitro Bioaccessibility of Carotenoids and Chlorophylls in a Diverse Collection of Spinach Accessions and Commercial Cultivars

Spinach, a nutrient-dense, green-leafy vegetable, is a rich source of carotenoid and chlorophyll bioactives. While the content of bioactives is known to vary with the genotype, variation in bioaccessibility is unknown. Bioaccessibility was explored in 71 greenhouse-grown spinach genotypes in fall and spring 2018/2019. Spinach was phenotyped for its greenness, leaf texture, leaf shape, and SPAD chlorophyll content. Postharvest, spinach was washed, blanched, and homogenized prior to assessment of bioactive bioaccessibility using a novel high-throughput in vitro digestion model followed by high-performance liquid chromatography with a photodiode array detector analysis. There was a significant variation in the bioaccessible content for all bioactives (p < 0.05), except for chlorophyll b (p = 0.063) in spring-grown spinach. The correlation coefficients of bioaccessible contents between seasons reveal that lutein (r = 0.52) and β-carotene (r = 0.55) were correlated to a greater extent than chlorophyll a (r = 0.38) and chlorophyll b (r = 0.19). The results suggest that carotenoid and chlorophyll bioaccessible contents may vary based on spinach genotypes and may be stable across seasons.

A Guide to Human Zinc Absorption: General Overview and Recent Advances of In Vitro Intestinal Models

Zinc absorption in the small intestine is one of the main mechanisms regulating the systemic homeostasis of this essential trace element. This review summarizes the key aspects of human zinc homeostasis and distribution. In particular, current knowledge on human intestinal zinc absorption and the influence of diet-derived factors on bioaccessibility and bioavailability as well as intrinsic luminal and basolateral factors with an impact on zinc uptake are discussed. Their investigation is increasingly performed using in vitro cellular intestinal models, which are continually being refined and keep gaining importance for studying zinc uptake and transport via the human intestinal epithelium. The vast majority of these models is based on the human intestinal cell line Caco-2 in combination with other relevant components of the intestinal epithelium, such as mucin-secreting goblet cells and in vitro digestion models, and applying improved compositions of apical and basolateral media to mimic the in vivo situation as closely as possible. Particular emphasis is placed on summarizing previous applications as well as key results of these models, comparing their results to data obtained in humans, and discussing their advantages and limitations.

Salivary Cystatin SN Binds to Phytic Acid In Vitro and Is a Predictor of Nonheme Iron Bioavailability with Phytic Acid Supplementation in a Proof of Concept Pilot Study

BACKGROUND

Acute phytic acid intake has been found to decrease iron bioavailability; however, repeated phytic acid consumption leads to iron absorption adaptation. Salivary proline-rich proteins (PRPs) have been shown to inhibit iron chelation to tannins and may mediate similar iron absorption adaptation with phytic acid intake.

OBJECTIVES

The objectives of this study were to determine whether salivary proteins bind to phytic acid in vitro, and to explore a proof of concept in a pilot study that examined the impact of 4-wk, daily phytic acid supplementation on individuals' iron status, bioavailability, and salivary PRP concentrations.

METHODS

High-performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization-time of flight were used to characterize in vitro salivary protein-phytic acid interactions. Nonanemic women (n = 7) consumed 350 mg phytic acid supplements 3 times daily for 4 wk, and meal challenges were employed to determine iron bioavailability, iron status, and salivary protein concentrations before and after supplementation periods. Enzyme-linked immunosorbent assay (ELISA) analysis of purified protein fractions and participant saliva identified proteins bound to phytic acid.

RESULTS

In vitro salivary protein-phytic acid interaction identified cystatin SN, a non-proline rich salivary protein, as the specific bound protein to phytic acid. Iron bioavailability (P = 0.32), hemoglobin (P = 0.72), and serum ferritin (P = 0.08) concentrations were not reduced from week 0 to week 4 after phytic acid supplementation. Basic PRPs and cystatin SN concentrations were positively correlated with iron bioavailability at week 4.

CONCLUSIONS

Overall, results suggest that phytic acid binds to the non-PRP cystatin SN and that salivary protein production may improve iron bioavailability with phytic acid consumption.

Exploring the nutritional and phytochemical potential of sorghum in food processing for food security

Purpose

Sorghum is quite comparable to wheat, rich source of nutrients with various health benefits, and therefore considered as a grain of future. The purpose of this paper is to review the bioactive active compounds, health benefits and processing of the sorghum. Sorghum is utilized for animal feeding rather than the human food usage. Therefore, this paper focuses on the emerging new health foods with benefits of the sorghum.

Design/methodology/approach

Major well-known bibliometric information sources searched were the Web of Science, Google Scholar, Scopus and PubMed. Several keywords like nutritional value of sorghum, bioactive compounds present in sorghum, health benefits of sorghum and processing of sorghum were chosen to obtain a large range of papers to be analyzed. A final inventory of 91 scientific sources was made after sorting and classifying them according to different criteria based on topic, academic field country of origin and year of publication.

Findings

From the literature reviewed, sorghum processing through various methods, including milling, malting, fermentation and blanching, bioactive compounds, as well as health benefits of sorghum were found and discussed.

Originality/value

Through this paper, possible processing methods and health benefits of sorghum are discussed after detailed studies of literature from journal articles.

Barriers impairing mineral bioaccessibility and bioavailability in plant-based foods and the perspectives for food processing

Plant-based foods gain more importance since they play a key role in sustainable, low-meat and healthy diets. In developing countries, these food products, especially legumes and cereals, are important staple foods. Nevertheless, the question arises on how efficient they are to deliver minerals and if it is useful to encourage their consumption to reduce the prevalence of mineral deficiencies? This review paper focuses on the discrepancy between the mineral content and the amount of minerals that can be released and absorbed from plant-based foods during human digestion which can be attributed to several inherent factors such as the presence of mineral antinutrients (phytic acid, polyphenols and dietary fiber) and physical barriers (surrounding macronutrients and cell wall). Further, this review paper summarizes the effects of different processing techniques (milling, soaking, dehulling, fermentation, germination and thermal processing) on mineral bioaccessibility and bioavailability of plant-based foods. The positive impact of these techniques mostly relies on the fact that antinutrients levels are reduced due to removal of fractions rich in antinutrients and/or due to their leaching into the processing liquid. Although processing can have a positive effect, it also can induce leaching out of minerals and a reduced mineral bioaccessibility and bioavailability.

Nutritionally Enhanced Sorghum for the Arid and Semiarid Tropical Areas of Africa

To help alleviate malnutrition in Africa, nutritionally enhanced sorghum was developed through genetic transformation to increase pro-vitamin A (β-carotene) accumulation and stability, to improve iron and zinc bioavailability, and to improve protein digestibility. Through many years of efforts, significant achievements have been made for these goals. We generated nutritionally enhanced sorghum lines with enhanced and stabilized pro-vitamin A that provide 20-90% of the Estimated Average Requirement (EAR) for children under age 3, lines with a 90% reduction in phytate that increase iron and zinc bioavailability and provide 40-80% of the EAR for iron and zinc, and lines that show no reduction in protein digestibility after cooking compared with normal levels. Once these nutritionally enhanced sorghum lines have undergone biosafety examination and have been deregulated, they will be ready for incorporation into sorghum varieties that will benefit Africa and other areas that rely upon sorghum as a staple food.

Gut Microbiota and Iron: The Crucial Actors in Health and Disease

Iron (Fe) is a highly ample metal on planet earth (~35% of the Earth’s mass) and is particularly essential for most life forms, including from bacteria to mammals. Nonetheless, iron deficiency is highly prevalent in developing countries, and oral administration of this metal is so far the most effective treatment for human beings. Notably, the excessive amount of unabsorbed iron leave unappreciated side effects at the highly interactive host–microbe interface of the human gastrointestinal tract. Recent advances in elucidating the molecular basis of interactions between iron and gut microbiota shed new light(s) on the health and pathogenesis of intestinal inflammatory diseases. We here aim to present the dynamic modulation of intestinal microbiota by iron availability, and conversely, the influence on dietary iron absorption in the gut. The central part of this review is intended to summarize our current understanding about the effects of luminal iron on host–microbe interactions in the context of human health and disease.

Intersection of Iron and Copper Metabolism in the Mammalian Intestine and Liver

Iron and copper have similar physiochemical properties; thus, physiologically relevant interactions seem likely. Indeed, points of intersection between these two essential trace minerals have been recognized for many decades, but mechanistic details have been lacking. Investigations in recent years have revealed that copper may positively influence iron homeostasis, and also that iron may antagonize copper metabolism. For example, when body iron stores are low, copper is apparently redistributed to tissues important for regulating iron balance, including enterocytes of upper small bowel, the liver, and blood. Copper in enterocytes may positively influence iron transport, and hepatic copper may enhance biosynthesis of a circulating ferroxidase, ceruloplasmin, which potentiates iron release from stores. Moreover, many intestinal genes related to iron absorption are transactivated by a hypoxia-inducible transcription factor, hypoxia-inducible factor-2α (HIF2α), during iron deficiency. Interestingly, copper influences the DNA-binding activity of the HIF factors, thus further exemplifying how copper may modulate intestinal iron homeostasis. Copper may also alter the activity of the iron-regulatory hormone hepcidin. Furthermore, copper depletion has been noted in iron-loading disorders, such as hereditary hemochromatosis. Copper depletion may also be caused by high-dose iron supplementation, raising concerns particularly in pregnancy when iron supplementation is widely recommended. This review will cover the basic physiology of intestinal iron and copper absorption as well as the metabolism of these minerals in the liver. Also considered in detail will be current experimental work in this field, with a focus on molecular aspects of intestinal and hepatic iron-copper interplay and how this relates to various disease states. © 2018 American Physiological Society. Compr Physiol 8:1433-1461, 2018.

Estimation of the bioaccessibility and bioavailability of Fe, Mn, Cu, and Zn in Chinese vegetables using the in vitro digestion/Caco-2 cell model: the influence of gut microbiota

The influence of the human gut microbiota on the bioaccessibility and bioavailability of trace elements in vegetables has barely been studied. An in vitro digestion model combining the physiologically based extraction test (PBET) and the Simulator of Human Intestinal Microbial Ecosystem (SHIME) was applied. Results showed that the gut microbiota increased the bioaccessibility of iron (Fe) in ten test vegetables by 1.3-1.8 times, but reduced the bioaccessibility of manganese (Mn), copper (Cu), and zinc (Zn) in vegetables in the colon phase by 3.7% to 89.6%, 24.8% to 100.0%, and 59.9% to 100.0%, respectively. Using the Caco-2 cell model to simulate the human absorption process, the bioavailable contents and the bioavailability of the trace elements were further determined. Swamp cabbage was the best source of Fe and Cu; spinach and lettuce provided the highest amounts of bioavailable Mn and Zn, respectively. Referring to the daily reference intakes of trace elements, the obtained data provide a scientific basis for both reasonable ingestion of vegetables in diets and diversification of diets.

Higher iron bioavailability of a human-like collagen iron complex

Iron deficiency remains a public health problem around the world due to low iron intake and/or bioavailability. FeSO₄, ferrous succinate, and ferrous glycinate chelate are rich in iron but have poor bioavailability. To solve the problem of iron deficiency, following previous research studies, a thiolated human-like collagen-ironcomplex supplement with a high iron content was prepared in an anaerobic workstation. In addition, cell viability tests were evaluated after conducting an MTT assay, and a quantitative analysis of the thiolated human-like collagen-iron digesta samples was performed using the SDS-PAGE method coupled with gel filtration chromatography. The iron bioavailability was assessed using Caco-2 cell monolayers and iron-deficiency anemia mice models. The results showed that (1) one mole of thiolated human-like collagen-iron possessed approximately 35.34 moles of iron; (2) thiolated human-like collagen-iron did not exhibit cytotoxity and (3) thiolated human-like collagen- iron digesta samples had higher bioavailability than other iron supplements, including FeSO₄, ferrous succinate, ferrous glycine chelate and thiolated human-like collagen-Fe iron. Finally, the iron bioavailability was significantly enhanced by vitamin C. These results indicated that thiolated human-like collagen-iron is a promising iron supplement for use in the future.

Sorghum (Sorghum bicolor L.): Nutrients, bioactive compounds, and potential impact on human health

Sorghum is the fifth most produced cereal in the world and is a source of nutrients and bioactive compounds for the human diet. We summarize the recent findings concerning the nutrients and bioactive compounds of sorghum and its potential impact on human health, analyzing the limitations and positive points of the studies and proposing directions for future research. Sorghum is basically composed of starch, which is more slowly digested than that of other cereals, has low digestibility proteins and unsaturated lipids, and is a source of some minerals and vitamins. Furthermore, most sorghum varieties are rich in phenolic compounds, especially 3-deoxyanthocyanidins and tannins. The results obtained in vitro and in animals have shown that phenolics compounds and fat soluble compounds (polycosanols) isolated from sorghum benefit the gut microbiota and parameters related to obesity, oxidative stress, inflammation, diabetes, dyslipidemia, cancer, and hypertension. The effects of whole sorghum and its fractions on human health need to be evaluated. In conclusion, sorghum is a source of nutrients and bioactive compounds, especially 3-deoxyanthocyanidins, tannins, and polycosanols, which beneficially modulate, in vitro and in animals, parameters related to noncommunicable diseases. Studies should be conducted to evaluate the effects of different processing on protein and starch digestibility of sorghum as well as on the profile and bioavailability of its bioactive compounds, especially 3-deoxyanthocyanidins and tannins. Furthermore, the benefits resulting from the interaction of bioactive compounds in sorghum and human microbiota should be studied.

Evaluation of iron and zinc bioavailability of beans targeted for biofortification using in vitro and in vivo models and their effect on the nutritional status of preschool children

BACKGROUND

Biofortified beans have been produced with higher nutrient concentrations. The objective was to evaluate the in vitro and in vivo iron and zinc bioavailability of common beans Pontal (PO), targeted for biofortification, compared with conventional Perola (PE) and their effects on the iron and zinc nutritional status of preschool children.

RESULTS

In Caco-2 cells, PO and PE beans did not show differences in ferritin (PO, 13.1 ± 1.4; PE, 13.6 ± 1.4 ng mg(-1) protein) or zinc uptake (PO, 15.9 ± 1.5; PE, 15.5 ± 3.5 µmol mg(-1) protein). In the rat, PO and PE beans presented high iron bioavailability (PO, 109.6 ± 29.5; PE, 110.7 ± 13.9%). In preschool children, no changes were observed in iron and zinc nutritional status comparing before and after PO consumption (ferritin, 41.2 ± 23.2 and 28.9 ± 40.4 µg L(-1) ; hemoglobin, 13.7 ± 2.2 and 13.1 ± 3.2 g dL(-1) ; plasma zinc, 119.2 ± 24.5 and 133.9 ± 57.7 µg dL(-1) ; erythrocyte zinc, 53.5 ± 13.8 and 59.4 ± 17.1 µg g(-1) hemoglobin).

CONCLUSION

Iron and zinc bioavailability in PO and PE beans was not statistically different using either cell culture, animal or human models. Efforts should focus on increasing mineral bioavailability of beans targeted for biofortification.

Replacing electrolytic iron in a fortification-mix with NaFeEDTA increases both iron and zinc availabilities in traditional African maize porridges

While replacing electrolytic iron with NaFeEDTA in multi-micronutrient fortification-mixes is a popular option, there is no information about the effect on the iron and zinc availabilities in African staple foods. This study evaluated the effects of adding a multi-micronutrient fortification-mix, with no iron, electrolytic iron or NaFeEDTA on the availabilities of iron and zinc from thick and fermented special-grade maize porridges using a Caco-2 cell model. Replacing electrolytic iron with NaFeEDTA significantly (p ⩽ 0.05) increased iron and, importantly zinc, availabilities in both the thick (2.16% vs. 1.45% and 2.51% vs. 2.29%, respectively) and fermented (3.35% vs. 2.66% and 3.04% vs. 2.61%, respectively) porridges. Some of the NaFeEDTA complexes perhaps partially dissociated because of pH changes during simulated digestion, binding with zinc and increasing its availability. NaFeEDTA in a multi-micronutrient fortification-mix, added to less refined, high phytate maize meal, would be more effective than electrolytic iron in addressing both iron and zinc deficiencies in low socio-economic populations of sub-Saharan Africa.

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.

Use of an in vitro digestion method to estimate human bioaccessibility of Cd in vegetables grown in smelter-impacted soils: the influence of cooking

Metal contamination of urban soils and homegrown vegetables has caused major concern. Some studies showed that cadmium (Cd) was among the most significant hazards in kitchen garden soils and prolonged exposure to this metal could cause deleterious health effects in humans. In general, most risk assessment procedures are based on total concentrations of metals in vegetables. The present study assesses human bioaccessibility of Cd in vegetables cultivated in smelter-impacted kitchen garden soils. Seven vegetables (radish, lettuce, French bean, carrot, leek, tomato, and potato) were considered. Using the UBM protocol (unified BARGE bioaccessibility method), the bioaccessibility of Cd was measured in raw/cooked vegetables. A considerable amount of Cd was mobilized from raw vegetables during the digestion process (on average 85% in the gastric phase and 69% in the gastrointestinal phase), which could be attributed to a high uptake of Cd during the growth of the vegetables. Most Cd is accumulated in the vacuoles of plant cells, except what is absorbed by the cell wall, allowing Cd to be released from plant tissues under moderate conditions. Cooking by the steaming process generally increased the bioaccessibility of Cd in French bean, carrot, and leek. For potato, few or no significant differences of Cd bioaccessibility were observed after the steaming process, while the frying process strongly decreased bioaccessibility in both phases. The estimation of metal bioaccessibility in vegetables is helpful for human health risk assessment.

Potential contribution of African green leafy vegetables and maize porridge composite meals to iron and zinc nutrition

OBJECTIVES

The aim of this study was to determine the mineral nutritive value of different traditional African green leafy vegetable (GLV) dishes and their composite meals with fortified and unfortified maize porridge.

METHODS

The mineral (iron, zinc, and calcium) and antinutrient (phytate, total phenolics, and tannins) contents and in vitro bioaccessibility of iron and zinc were analyzed. The iron and zinc contents and bioaccessibilities were used to calculate contribution these dishes and meals could make toward the recommended daily requirements and absolute requirements of vulnerable populations.

RESULTS

It was found that the GLV dishes contained average amounts of zinc (2.8-3.2 mg/100 g, dry base [db]), but were high in both iron (12.5-23.4 mg/100 g, db) and antinutrients (phytate 1420-2089 mg/100 g, db; condensed tannins 105-203 mg/100 g, db). The iron bioaccessibility and amount of bioaccessible iron ranged between 6.7% and 45.2% and 0.9 and 5.11 mg/100 g, db, respectively. The zinc bioaccessibility and amount of bioaccessible zinc ranged between 6.4% and 12.7% and 0.63 and 1.63 mg/100 g, db, respectively.

CONCLUSION

Importantly, although compositing the GLV dishes with fortified maize porridges decreases the iron and zinc contents, because of the low antinutrient content of the maize meal, the amount of bioaccessible iron and zinc in the meal increases.

Phosphate and zinc transport and signalling in plants: toward a better understanding of their homeostasis interaction

Inorganic phosphate (Pi) and zinc (Zn) are two essential nutrients for plant growth. In soils, these two minerals are either present in low amounts or are poorly available to plants. Consequently, worldwide agriculture has become dependent on external sources of Pi and Zn fertilizers to increase crop yields. However, this strategy is neither economically nor ecologically sustainable in the long term, particularly for Pi, which is a non-renewable resource. To date, research has emphasized the analysis of mineral nutrition considering each nutrient individually, and showed that Pi and Zn homeostasis is highly regulated in a complex process. Interestingly, numerous observations point to an unexpected interconnection between the homeostasis of the two nutrients. Nevertheless, despite their fundamental importance, the molecular bases and biological significance of these interactions remain largely unknown. Such interconnections can account for shortcomings of current agronomic models that typically focus on improving the assimilation of individual elements. Here, current knowledge on the regulation of the transport and signalling of Pi and Zn individually is reviewed, and then insights are provided on the recent progress made towards a better understanding of the Zn-Pi homeostasis interaction in plants.

Combating Mineral Malnutrition through Iron and Zinc Biofortification of Cereals

 Iron and zinc are 2 important nutrients in the human diet. Their deficiencies in humans lead to a variety of health-related problems. Iron and zinc biofortification of cereals is considered a cost-effective solution to overcome the malnutrition of these minerals. Biofortification aims at either increasing accumulation of these minerals in edible parts, endosperm, or to increase their bioavailability. Iron and zinc fertilization management positively influence their accumulation in cereal grains. Regarding genetic strategies, quantitative genetic studies show the existence of ample variation for iron and zinc accumulation as well as inhibitors or promoters of their bioavailability in cereal grains. However, the genes underlying this variation have rarely been identified and never used in breeding programs. Genetically modified cereals developed by modulation of genes involved in iron and zinc homeostasis, or genes influencing bioavailability, have shown promising results. However, iron and zinc concentration were quantified in the whole grains during most of the studies, whereas a significant proportion of them is lost during milling. This makes it difficult to realistically assess the effectiveness of the different strategies. Moreover, modifications in the accumulation of toxic elements, like cadmium and arsenic, that are of concern for food safety are rarely determined. Trials in living organisms with iron- and zinc-biofortified cereals also remain to be undertaken. This review focuses on the common challenges and their possible solutions related to agronomic as well as genetic iron and zinc biofortification of cereals.