Phytic acid-to-iron molar ratio rather than polyphenol concentration determines iron bioavailability in whole-cowpea meal among young women

Vitamin C-Rich Guava Consumed with Mungbean Dal Reduces Anemia and Increases Hemoglobin but not Iron Stores: A Randomized Controlled Trial of Food-to-Food Fortification in Indian Children

BACKGROUND

Adding vitamin C-rich fruit to staples containing iron could be an effective strategy to improve iron bioavailability and thereby reduce iron-deficiency anemia in children.

OBJECTIVES

We aimed to assess the effect of consuming a mungbean-based meal with or without guava fruit on body iron stores, hemoglobin concentration, and anemia of children as part of a school feeding program.

METHODS

We conducted a 7-mo randomized, controlled trial with 6- to 10-y-old school children (n = 200; 46% anemic, 71% iron-deficient) from a rural community in Haryana, North India. Children were assigned to 2 treatment groups to daily receive either a meal of mungbean dal only (3.0 mg iron; vitamin C:iron molar ratio ∼0.5:1), or mungbean dal with fresh guava (3.2 mg iron; ∼170 mg vitamin C; molar ratio ∼18:1). Meals were served every school day under supervision. The primary outcome was body iron stores, whereas concentrations of hemoglobin and other iron indicators were secondary outcomes.

RESULTS

Daily consumption of mungbean dal along with guava did not result in an overall improvement of body iron stores [mean treatment effect: 0.65 mg/kg body weight; 95% confidence interval (CI): -0.34, 1.63; P = 0.197]. However, compared with children who consumed mungbean dal only, children in the guava group showed a larger increase in hemoglobin concentration (3.7 g/L; 95% CI: 1.6, 5.6; P = 0.001), and a larger drop in the prevalence of anemia (-51%; 95% CIs: -74, -10; P = 0.022) and iron-deficiency anemia (-56%, 95% CI: -83, 13; P = 0.087). These effects were more pronounced in children who were iron deficient at study start.

CONCLUSIONS

Addition of guava to a mungbean-based meal containing a moderate amount of iron increased hemoglobin and reduced anemia but did not provide enough additional absorbed iron to also increase body iron stores. Food-to-food fortification by inclusion of vitamin C-rich fruits in iron-containing school meals may help alleviate the burden of anemia in children.

TRIAL REGISTRATION NUMBER

This trial was registered at https://clinicaltrials.gov/ct2/show/NCT01191463.

Enhancing micronutrient absorption through simultaneous fortification and phytic acid degradation

Phytic acid (PA), an endogenous antinutrient in cereals and legumes, hinders mineral absorption by forming less bioavailable, stable PA-mineral complexes. For individual micronutrients, the PA-to-mineral molar ratio below the critical level ensures better bioavailability and is achieved by adding minerals or removing PA from cereals and pulses. Although several PA reduction and fortification strategies are available, the inability to completely eradicate or degrade PA using available techniques always subdues fortification's impact by hindering fortified micronutrient absorption. The bioavailability of micronutrients could be increased through simultaneous PA degradation and fortification. Following primary PA reduction of the raw material, the fortification step should also incorporate additional essential control stages to further PA inactivation, improving micronutrient absorption. In this review, the chemistry of PA interaction with metal ions, associated controlling parameters, and its impact on PA reduction during fortification is also evaluated, and further suggestions were made for the fortification's success.

Revisiting phytate-element interactions: implications for iron, zinc and calcium bioavailability, with emphasis on legumes

Myo-Inositol hexakisphosphate or phytic acid concentration is a prominent factor known to impede divalent element bioavailability in vegetal foods including legumes. Both in vivo and in vitro studies have suggested that phytic acid and other plant-based constituents may synergistically form insoluble complexes affecting bioavailability of essential elements. This review provides an overview of existing investigations on the role of phytic acid in the binding, solubility and bioavailability of iron, zinc and calcium with a focus on legumes. Given the presence of various interference factors within legume matrices, current findings suggest that the commonly adapted approach of using phytic acid-element molar ratios as a bioavailability predictor may only be valid in limited circumstances. In particular, differences between protein properties and molar concentrations of other interacting ions are likely responsible for the observed poor correlations. The role of phytate degradation in element bioavailability has been previously examined, and in this review we re-emphasize its importance as a tool to enhance mineral bioavailability of mineral fortified legume crops. Food processing strategies to achieve phytate reduction were identified as promising tools to increase mineral bioavailability and included germination and fermentation, particularly when other bioavailability promoters (e.g. NaCl) are simultaneously added.

Salivary cystatin SN is a factor predicting iron bioavailability after phytic acid rich meals in female participants

Phytic acid is an inhibitor of iron bioavailability, but it has been suggested that individuals may adapt to phytic acid over time, and that the salivary protein, cystatin SN, may be involved. This study evaluated the relationship between human cystatin SN levels and iron bioavailability after a phytic acid rich meal. Three groups of ten women consumed meals with: (1) 500 mg phytate sprinkles, (2) 500 mg phytate capsules, or (3) no phytic acid. Iron bioavailability was measured by the mealtime percentage of maximum iron recovery; cystatin SN was measured pre-and post-meal by enzyme-linked immunosorbent assay. Pre-to-post meal cystatin SN was positively correlated with improved iron bioavailability in group 1. Pre-to-post meal cystatin SN was correlated with improved iron absorption in groups 1 and 2. Cystatin SN recovery after phytic acid rich meals may be a physiological factor predicting iron bioavailability.

Food Pattern Modeling as an Alternative Assessment Method to Multiday Dietary Recalls for Iron-Related Nutrients: A Proof-of-Concept Study

There are barriers to in-depth memory-based dietary assessment techniques in community-based research. Food pattern modeling may be an alternative method to traditional assessment techniques. The objective of this study was to pilot a comparison of food pattern modeling to 24 h diet recalls for predicting hematological outcomes of iron status. Data from 3-24 h dietary recalls in 27 women were analyzed by two methods: mean dietary intake estimates or food pattern modeling. Food pattern modeling was used to determine the total inventory of foods consumed with iron, phytate, or ascorbic acid or iron-phytate ratios. Each variable was analyzed for its relationship to hemoglobin, ferritin, and acute iron absorption from a meal challenge study by creating receiver operating characteristic (ROC) curves. There were no differences in ROC curves or diagnostic accuracies between food pattern modeling or mean dietary intake estimates for iron, vitamin C, phytate, or phytate-iron ratios for estimating hemoglobin or ferritin values (p > 0.05). Food pattern modeling was inferior to mean dietary estimates for acute iron absorption, suggesting that more detailed methods may be necessary for studies with sensitive or acute dietary measurement outcomes. Food pattern modeling for total iron, vitamin C, phytate, and phytate-iron ratios may be comparable to detailed memory-based recalls for larger studies assessing the impact of foods on iron status.

Clinically Relevant Herb-Micronutrient Interactions: When Botanicals, Minerals, and Vitamins Collide

The ability of certain foods to impair or augment the absorption of various vitamins and minerals has been recognized for many years. However, the contribution of botanical dietary supplements (BDSs) to altered micronutrient disposition has received little attention. Almost half of the US population uses some type of dietary supplement on a regular basis, with vitamin and mineral supplements constituting the majority of these products. BDS usage has also risen considerably over the last 2 decades, and a number of clinically relevant herb-drug interactions have been identified during this time. BDSs are formulated as concentrated plant extracts containing a plethora of unique phytochemicals not commonly found in the normal diet. Many of these uncommon phytochemicals can modulate various xenobiotic enzymes and transporters present in both the intestine and liver. Therefore, it is likely that the mechanisms underlying many herb-drug interactions can also affect micronutrient absorption, distribution, metabolism, and excretion. To date, very few prospective studies have attempted to characterize the prevalence and clinical relevance of herb-micronutrient interactions. Current research indicates that certain BDSs can reduce iron, folate, and ascorbate absorption, and others contribute to heavy metal intoxication. Researchers in the field of nutrition may not appreciate many of the idiosyncrasies of BDSs regarding product quality and dosage form performance. Failure to account for these eccentricities can adversely affect the outcome and interpretation of any prospective herb-micronutrient interaction study. This review highlights several clinically relevant herb-micronutrient interactions and describes several common pitfalls that often beset clinical research with BDSs.

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.

Soya, maize, and sorghum-based ready-to-use therapeutic food with amino acid is as efficacious as the standard milk and peanut paste-based formulation for the treatment of severe acute malnutrition in children: a noninferiority individually randomized controlled efficacy clinical trial in Malawi

Background: Development of more cost-effective ready-to-use therapeutic food (RUTF) is a global public health priority. To date, previous lower-cost recipes have been less effective than the standard peanut and milk (PM)-based RUTF, particularly in children aged <24 mo.Objective: We aimed to compare the efficacy of the PM-RUTF to a milk-free soya, maize, and sorghum (FSMS)-RUTF enriched with crystalline amino acids without cow milk powder and a milk, soya, maize, and sorghum (MSMS)-RUTF containing 9.3% skim cow milk powder.Design: This nonblinded, 3-arm, parallel-group, simple randomized controlled trial enrolled Malawian children with severe acute malnutrition.Results: In intention-to-treat analyses, FSMS-RUTF showed noninferiority for recovery rates in children aged 24-59 mo (Δ: -1.9%; 95% CI: -9.5%, 5.6%) and 6-23 mo (Δ: -0.2%; 95% CI: -7.5%, 7.1%) compared with PM-RUTF. MSMS-RUTF also showed noninferiority for recovery rates in children aged 24-59 mo (Δ: 0.0%; 95% CI: -7.3%, 7.4%) and 6-23 mo (Δ: 0.6%; 95% CI: -4.3%, 5.5%). Noninferiority in recovery rates was also observed in per-protocol analyses. For length of stay in the program (time to cure), both FSMS-RUTF in children aged 24-59 mo (Δ: 2.8 d; 95% CI: -0.8, 6.5 d) and 6-23 mo (Δ: 3.4 d; 95% CI: -1.2, 8.0 d) and MSMS-RUTF in children aged 24-59 mo (Δ: 0.2 d; 95% CI: -3.1, 3.6 d) and 6-23 mo (Δ: 1.2 d; 95% CI: -3.4, 5.8 d) were not inferior to PM-RUTF. FSMS-RUTF was also significantly better than PM-RUTF at increasing hemoglobin and body iron stores in anemic children, with mean hemoglobin increases of 2.1 (95% CI: 1.6, 2.6) and 1.3 (95% CI: 0.9, 1.8) and mean body iron store increases of 2.0 (95% CI: 0.8, 3.3) and 0.1 (95% CI: -1.1, 1.3) for FSMS-RUTF and PM-RUTF, respectively.Conclusions: FSMS-RUTF without milk is efficacious in the treatment of severe acute malnutrition in children aged 6-23 and 24-59 mo. It is also better at correcting iron deficiency anemia than PM-RUTF. This trial was registered at www.pactr.org as PACTR201505001101224.

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.

Agronomic Approach of Zinc Biofortification Can Increase Zinc Bioavailability in Wheat Flour and thereby Reduce Zinc Deficiency in Humans

Zinc (Zn) deficiency is a common disorder of humans in developing countries. The effect of Zn biofortification (via application of six rates of Zn fertilizer to soil) on Zn bioavailability in wheat grain and flour and its impacts on human health was evaluated. Zn bioavailability was estimated with a trivariate model that included Zn homeostasis in the human intestine. As the rate of Zn fertilization increased, the Zn concentration increased in all flour fractions, but the percentages of Zn in standard flour (25%) and bran (75%) relative to total grain Zn were constant. Phytic acid (PA) concentrations in grain and flours were unaffected by Zn biofortification. Zn bioavailability and the health impact, as indicated by disability-adjusted life years (DALYs) saved, increased with the Zn application rate and were greater in standard and refined flour than in whole grain and coarse flour. The biofortified standard and refined flour obtained with application of 50 kg/ha ZnSO₄·7H₂O met the health requirement (3 mg of Zn obtained from 300 g of wheat flour) and reduced DALYs by >20%. Although Zn biofortification increased Zn bioavailability in standard and refined flour, it did not reduce the bioavailability of iron, manganese, or copper in wheat flour.

The Impact of Tannin Consumption on Iron Bioavailability and Status: A Narrative Review

Iron deficiency remains a global health issue, and antinutritional factors, such as tannins, are often cited as contributors to the high prevalence of deficiency. Despite this, tannin-rich diets may have potential beneficial cardiovascular and cancer-fighting properties because of the antioxidant activity of tannins. Furthermore, epidemiologic studies and long-term trials involving participants who consumed diets rich in antinutritional factors, particularly tannins, conflict with single-meal bioavailability studies. The purpose of this narrative review is to determine the effect of tannins on iron bioavailability and status and establish whether adaptation to tannins reduces the antinutritional effects of tannins over time. We also aimed to compare tannins used in iron studies. Common themes related to iron bioavailability and iron status with tannin consumption were collected and collated for summary and synthesis based on models and subjects used. Overall, there was dissonance between iron bioavailability and status in studies. Single-meal studies with hydrolyzable and oligomeric catechin and epicatechin tannins (tea and tannic acid) generally support reductions in bioavailability related to tannin consumption but not consumption of condensed tannin, which are more commonly found in food. Long-term animal model, epidemiologic, and multimeal studies generally do not support changes in iron status related to tannin intake. Studies suggest that long-term tannin consumption may impact iron status in a different manner than single-meal studies or bioavailability iron models predict. Furthermore, iron bioavailability studies that use condensed tannins, which are more commonly consumed, may better predict mealtime iron bioavailability. More research is needed to develop representative antinutritional iron studies and investigate mechanisms underlying the adaptation to tannins and other antinutritional factors that occur over time.

Cowpea (Vigna unguiculata L. Walp), a renewed multipurpose crop for a more sustainable agri-food system: nutritional advantages and constraints

The growing awareness of the relevance of food composition for human health has increased the interest of the inclusion of high proportions of fruits and vegetables in diets. To reach the objective of more balanced diets, an increased consumption of legumes, which constitutes a sustainable source of essential nutrients, particularly low-cost protein, is of special relevance. However, the consumption of legumes also entails some constraints that need to be addressed to avoid a deleterious impact on consumers' wellbeing and health. The value of legumes as a source of nutrients depends on a plethora of factors, including genetic characteristics, agro-climatic conditions, and postharvest management that modulate the dietary effect of edible seeds and vegetative material. Thus, more comprehensive information regarding composition, especially their nutritional and anti-nutritional compounds, digestibility, and alternative processing procedures is essential. These were the challenges to write this review, which focusses on the nutritional and anti-nutritional composition of Vigna unguiculata L. Walp, an emerging crop all over the world intended to provide a rational support for the development of valuable foods and feeds of increased commercial value. © 2016 Society of Chemical Industry.

Non-Heme Iron Absorption and Utilization from Typical Whole Chinese Diets in Young Chinese Urban Men Measured by a Double-Labeled Stable Isotope Technique

BACKGROUND

This study was to observe the non-heme iron absorption and biological utilization from typical whole Chinese diets in young Chinese healthy urban men, and to observe if the iron absorption and utilization could be affected by the staple food patterns of Southern and Northern China.

MATERIALS AND METHODS

Twenty-two young urban men aged 18-24 years were recruited and randomly assigned to two groups in which the staple food was rice and steamed buns, respectively. Each subject received 3 meals containing approximately 3.25 mg stable 57FeSO4 (the ratio of 57Fe content in breakfast, lunch and dinner was 1:2:2) daily for 2 consecutive days. In addition, approximately 2.4 mg 58FeSO4 was administered intravenously to each subject at 30-60 min after dinner each day. Blood samples were collected from each subject to measure the enrichment of the 57Fe and 58Fe. Fourteen days after the experimental diet, non-heme iron absorption was assessed by measuring 57Fe incorporation into red blood cells, and absorbed iron utilization was determined according to the red blood cell incorporation of intravenously infused 58Fe SO4.

RESULTS

Non-heme iron intake values overall, and in the rice and steamed buns groups were 12.8 ±2.1, 11.3±1.3 and 14.3±1.5 mg, respectively; the mean 57Fe absorption rates were 11±7%, 13±7%, and 8±4%, respectively; and the mean infused 58Fe utilization rates were 85±8%, 84±6%, and 85±10%, respectively. There was no significantly difference in the iron intakes, and 57Fe absorption and infused 58Fe utilization rates between rice and steamed buns groups (all P>0.05).

CONCLUSION

We present the non-heme iron absorption and utilization rates from typical whole Chinese diets among young Chinese healthy urban men, which was not affected by the representative staple food patterns of Southern and Northern China. This study will provide a basis for the setting of Chinese iron DRIs.

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 and Provitamin A from Sweet Potato- and Cereal-Based Complementary Foods

Iron and vitamin A deficiencies in childhood are public health problems in the developing world. Introduction of cereal-based complementary foods, that are often poor sources of both vitamin A and bioavailable iron, increases the risk of deficiency in young children. Alternative foods with higher levels of vitamin A and bioavailable iron could help alleviate these micronutrient deficiencies. The objective of this study was to compare iron bioavailability of β-carotene-rich sweet potato-based complementary foods (orange-flesh based sweet potato (OFSP) ComFa and cream-flesh sweet potato based (CFSP) ComFa with a household cereal-based complementary food (Weanimix) and a commercial cereal (Cerelac^®), using the in vitro digestion/Caco-2 cell model. Iron bioavailability relative to total iron, concentrations of iron-uptake inhibitors (fibre, phytates, and polyphenols), and enhancers (ascorbic acid, ß-carotene and fructose) was also evaluated. All foods contained similar amounts of iron, but bioavailability varied: Cerelac^® had the highest, followed by OFSP ComFa and Weanimix, which had equivalent bioavailable iron; CFSP ComFa had the lowest bioavailability. The high iron bioavailability from Cerelac^® was associated with the highest levels of ascorbic acid, and the lowest levels of inhibitors; polyphenols appeared to limit sweet potato-based food iron bioavailability. Taken together, the results do not support that CFSP- and OFSP ComFa are better sources of bioavailable iron compared with non-commercial/household cereal-based weaning foods; however, they may be a good source of provitamin A in the form of β-carotene.

Orange-fleshed sweet potato-based infant food is a better source of dietary vitamin A than a maize-legume blend as complementary food

BACKGROUND

White maize, which is widely used for complementary feeding and is seldom fortified at the household level, may be associated with the high prevalence of vitamin A deficiency among infants in low-income countries.

OBJECTIVE

The nutrient composition of complementary foods based on orange-fleshed sweet potato (OFSP) and cream-fleshed sweet potato (CFSP), maize-soybean-groundnut (Weanimix), and a proprietary wheat-based infant cereal (Nestlé Cerelac) were assessed using the Codex Standard (CODEX STAN 074-1981, Rev. 1-2006) specification as a reference. Additionally, the costs of OFSP complementary food, CFSP complementary food, and Weanimix production at the household level were estimated. Phytate and polyphenols, which limit the bioavailability of micronutrients, were assessed.

METHODS

Energy, macronutrients, and micronutrients listed as essential composition in the Codex Standard were determined and expressed as energy or nutrient density.

RESULTS

All the formulations met the stipulated energy and nutrient densities as specified in the Codex Standard. The beta-carotene content of OFSP complementary food exceeded the vitamin A specification (60 to 180 microg retinol activity equivalents/100 kcal). All the formulations except Weanimix contained measurable amounts of ascorbic acid (> or = 32.0 mg/100 g). The level of phytate in Weanimix was highest, about twice that of OFSP complementary food. The sweet potato-based foods contained about twice as much total polyphenols as the cereal-based products. The estimated production cost of OFSP complementary food was slightly higher (1.5 times) than that of Weanimix.

CONCLUSIONS

OFSP complementary food is a good source of beta-carotene and would therefore contribute to the vitamin A requirements of infants. Both OFSP complementary food and Weanimix may inhibit iron absorption because of their high levels of polyphenols and phytate, respectively, compared with those of Nestlé Cerelac.

Dietary approaches to assessing iron-related nutrition

PURPOSE OF REVIEW

Both dietary and nondietary factors contribute to iron deficiency, the most common nutritional deficiency worldwide. Identifying dietary factors associated with iron deficiency is challenging due to the number of components in food affecting iron absorption. This review describes recent advances in dietary approaches to assessing iron-related nutrition.

RECENT FINDINGS

Most research investigating the relationship between dietary intake and iron deficiency has focussed on individual foods and nutrients, despite several components in foods influencing iron absorption. More recently, studies have considered the overall diet and combinations of foods eaten, through the analysis of dietary patterns and practices. This includes the development and validation of dietary assessment tools to assess iron-related dietary patterns.

SUMMARY

Dietary pattern analysis which considers the whole diet and combinations of foods eaten may enhance our understanding of how diet impacts on iron deficiency. The analysis of dietary patterns offers an alternative and complementary approach to the traditional focus on individual foods and nutrients when investigating dietary factors associated with iron deficiency.

Seed coat removal improves iron bioavailability in cooked lentils: studies using an in vitro digestion/Caco-2 cell culture model

In this study we examined the range of Fe concentration and relative Fe bioavailability of 24 varieties of cooked lentils, as well as the impact of seed coat removal on Fe nutritional as well as antinutrient properties. Relative Fe bioavailability was assessed by the in vitro/Caco-2 cell culture method. While the Fe concentration of the whole lentil was moderately high (72.8 ± 10.8 μg/g, n = 24), the relative Fe bioavailability was moderate (2.4 ± 1.0 ng of ferritin/mg of protein). Although removing the seed coat reduced the Fe concentration by an average of 16.4 ± 9.4 μg/g, the bioavailability was significantly improved (+5.3 ± 2.2 ng of ferritin/mg of protein; p < 0.001), and the phytic acid concentration was reduced by 7% (p = 0.04). Like most legume seeds, the lentil seed coat contains a range of polyphenols known to inhibit Fe bioavailability. Thus, along with breeding for high Fe concentration and bioavailability (i.e., biofortification), seed coat removal appears to be a practical way to improve Fe bioavailability of the lentil.

Cowpeas in Northern Ghana and the factors that predict caregivers' intention to give them to schoolchildren

BACKGROUND

Cowpeas are important staple legumes among the rural poor in northern Ghana. Our objectives were to assess the iron and zinc content of cowpea landraces and identify factors that predict the intention of mothers/caregivers to give cowpeas to their schoolchildren.

METHODS AND FINDINGS

We performed biochemical analysis on 14 landraces of cowpeas and assessed the opinion of 120 caregiver-child pairs on constructs based on the combined model of the Theory of Planned Behaviour and Health Belief Model. We used correlations and multiple regressions to measure simple associations between constructs and identify predictive constructs. Cowpea landraces contained iron and zinc in the range of 4.9-8.2 mg/100 g d.w and 2.7-4.1 mg/100 g d.w respectively. The landraces also contained high amounts of phytate (477-1110 mg/100 g d.w) and polyphenol (327-1055 mg/100 g d.w). Intention of mothers was strongly associated (rs = 0.72, P<0.001) with and predicted (β = 0.63, P<0.001) behaviour. The constructs, barriers (β = -0.42, P = 0.001) and attitudes towards behaviour (β = 0.25, P<0.028), significantly predicted intention albeit the predictive ability of the model was weak.

CONCLUSIONS

We conclude that some cowpea landraces from northern Ghana have appreciable amounts of iron and zinc but probably with poor bioavailability. Attitudes towards giving cowpeas and perception of barriers are important predictors of caregivers' intention to give cowpeas to their schoolchildren. Finally our results suggest that increasing knowledge on nutritional benefits of cowpeas may increase health values caregivers hold for their children in support of giving cowpeas to schoolchildren.