Chemical and Toxicological Evaluation of Extracts of Fermented Red Acalypha (A Calypha Wilkes/A Na) : A Suggested Tea Adjunct

This study aimed to develop and assess the feasibility of a home-based method to reduce the phytate content of maize and improve zinc bioavailability from maizebased complementary diets in rural Malawi. A method of extracting phytate through the soaking of pounded maize was developed, and found to reduce phytate content to 49% of unrefined maize. An educational program was used to teach the processing method to mothers of children receiving complementary foods in rural Malawian communities. Samples of maize flour prepared by this process by participants were collected and analysed for phytate and zinc content. Of these, 70% of samples were found to be adequately prepared; mean phytate content of these samples was 48% of unprocessed, unrefined maize flour controls. Most participants found the cooked product to have an acceptable taste (99%) and texture (68%), and felt the processing method took little or no extra time (86%) and was culturally acceptable (96%). The phytate and zinc content of the processed maize flour samples analysed from community prepared samples was substituted into the dietary analysis of complementary foods for 9- to 11-month-old children (n = 31). The bioavailability of zinc from the complementary diet would predict an increase from low (24%) to moderate (33%) levels.     

Dietary diversification/modification strategies to enhance micronutrient content and bioavailability of diets in developing countries

Both cereal staples and household diets can be manipulated to enhance the content of micronutrients and/or alter the levels of absorption modifiers to improve micronutrient bioavailability. Strategies described range from plant breeding, use of fertilizers and genetic engineering to changes in food preparation and processing methods at the household level involving soaking, fermentation and germination. The impact of five household strategies designed to enhance the content and bioavailability of iron, zinc and calcium in a representative daily menu for rural Malawian preschool children has been calculated using food composition data. In the five strategies, relishes based on small dried fish replaced plant-based relishes, maize-based porridges prepared with maize flour soaked to reduce its hexa (IP-6)- and penta (IP-5)-inositol phosphate content replaced conventional porridges; and a pumpkin-leaf relish replaced sweet potato to increase the retinol content of the daily menu. Comparison of the calculated energy, nutrient, and phytate content, and [phytate]:[zinc] molar ratios of the five modified menus compared with the unmodified menu emphasizes that to ensure that the estimated requirements for iron and zinc are met, the optimal strategy includes dried fish relish twice daily together with porridges prepared using soaked (or fermented) maize flour to reduce their hexa- and penta-inositol phosphate content. Implementation of these household strategies has the potential to increase the bioavailability of iron and zinc in rural Malawian diets from low to high.     

Phytate, zinc, and calcium contents of 30 East African foods and their calculated phytate:Zn, Ca:phytate, and [Ca][phytate]/[Zn] molar ratios

Representative samples of 30 staple Malawian foods, raw and prepared “as eaten,” were analyzed for phytate using an anion-exchange method, and for calcium and zinc by flame atomic absorption spectrophotometry. Phytic acid contents expressed on a fresh weight (FW) basis ranged from 211–1089 mg/100 g for cereals and 166–1297 mg/100 g for legumes, to 4–97 mg/100 g for leaves, 10–59 mg/100 g for roots, and 11–25 mg/100 g for fruits. In general, leaves had the highest calcium content (81–514 mg/100 g FW), followed by kidney beans (90 mg/100 g FW), and dry pigeon peas (112 mg/100 g FW). The calcium content of other foods analyzed was relatively low. The zinc content of wild blight, cassava leaves, and okra leaves was comparable to that for the less refined cereals and legumes (i.e., > 1.0 mg/100 g FW), but higher than that of highly refined cereals, pumpkin leaves, chinese cabbage, and other foods analysed (i.e., < 1.0 mg/100 g FW). Cooking had no effect on the phytate content of cereals, but milling and fermentation reduced both the phytate and zinc contents of maize flour. The phytate:Zn molar ratios calculated for all cereals and most legumes analyzed were greater than 20:1. Corresponding Ca:phytate molar ratios were low. Fruits, except for mangoes, vegetables, and roots, had low phytate: Zn molar ratios, but their Ca:phytate and [Ca][phytate]/[Zn] molar ratios were high. Mangoes had high phytate:Zn, Ca:phytate, and [Ca][phytate]/[Zn] molar ratios. These analytical results suggest that the bioavailability of zinc in the Malawian diet is probably low, due to the high phytic acid content of the staple foods.     

Content of zinc, iron, calcium and their absorption inhibitors in foods commonly consumed in Ethiopia

The zinc, iron, calcium, phosphorus, phytate, tannin and moisture content of 36 foods consumed in rural Ethiopia were analysed. The foods analysed included those based on cereals, starchy tubers and roots, and legumes and vegetables as well as some fruits. Although many foods were relatively rich in zinc and iron, many also contained high levels of phytic acid and tannins, which impair bioavailability of zinc and iron. The phytate:zinc molar ratios were >20 for non-fermented cereal foods, >15 for legumes, and <12 for fermented cereals, starchy tubers and roots. Ratios >15 are associated with low bioavailability of zinc. Given the high iron content and the relatively favourable phytate:iron molar ratio, tef enjera was the best source of bioavailable iron of all foods analysed. Foods prepared from tef, enset and kale are rich sources of calcium. The consumption of diets based on cereals and legumes but poor in animal products can lead to deficiencies of zinc and iron. However, since fermentation can decrease the phytate content by a factor of 3–4, traditional household practices such as fermentation need to be encouraged to address the problem of zinc deficiency, which is particularly prevalent in Ethiopia.     

Zinc absorption from low-phytate hybrids of maize and their wild-type isohybrids

BACKGROUND: Identification of allelic variants in a single gene that determine the phytate content of maize kernels and the subsequent breeding of low-phytate maize have facilitated studies designed to determine quantitatively the effects of maize phytate on the bioavailability of minerals in maize. OBJECTIVE: The objective was to determine the relation between the fractional absorption of zinc (FAZ) and the phytate content and phytate:zinc molar ratios of maize tortillas prepared from hybrids with different phytate contents. DESIGN: Six healthy adults were fed, as the only food for 2 d, maize tortillas prepared from 1 of 2 low-phytate mutants: lpa1-1 (lpa1-1-LP) or Nutridense Low Phytate (ND-LP), which have phytate reductions of approximately 60% and approximately 80%, respectively, compared with their respective wild-type isohybrids. Four additional subjects were fed tortillas prepared from the corresponding wild-type isohybrids (lpa1-1-WT and ND-WT) according to the same study design. Meals were extrinsically labeled with zinc stable isotopes, and FAZ was determined with a dual-isotope-tracer ratio technique. Overall FAZ values were examined in relation to dietary phytate and phytate:zinc molar ratios by using a mixed nonlinear regression model. RESULTS: The mean (+/-SD) FAZ values from tortillas prepared from ND-LP, lpa1-1-LP, lpa1-1-WT, and ND-WT were 0.38 +/- 0.07, 0.28 +/- 0.04, 0.15 +/- 0.07, and 0.13 +/- 0.05, respectively. A negative relation (P < 0.001) was found between FAZ and both dietary phytate and the phytate:zinc molar ratio. The effect of dietary zinc (8-14 mg Zn/d) under these experimental conditions was not significant. CONCLUSIONS: FAZ from maize tortillas is positively related to the extent of phytate reduction achieved with low-phytate hybrids.     

Determination of phytate, iron, zinc, calcium contents and their molar ratios in commonly consumed raw and prepared food in malaysia

The inhibitory effect of phytate on the bioavailability of iron, zinc and calcium was determined by measuring their molar ratios. A total of 29 food samples consisting of 12 rice and rice products, 5 wheat and wheat products, 5 grains and cereal based products and 7 different popular varieties of cooked rice and rice products were selected. The phytate content was analysed using anion-exchange chromatography whereas mineral contents were analysed using atomic absorption spectrophotometry(AAS). One-way ANOVA test was used to statistically analyse the mean difference between the phytate and mineral contents between the food group samples. In general, results show that cooked products have lower content of phytate and minerals as compared to raw products. This could be due to the influence of the cooking method on phytate and mineral content in the food. Based on one-way ANOVA test, there were no significant difference in phytate and zinc content between four food groups (p >0.05). Significant differences were found only in iron and calcium content (p <0.05). Of the 29 food samples, 25 food samples had a phytate/iron molar ratio > 1, 5 food samples had a phytate/zinc molar ratio > 15 and 23 food samples had a phytate/calcium molar ratio of 0.24. These results show that although many of the food samples analysed had high mineral content, the high phytate content may impair the bioavailability of the mineral in the body.     

Phytic acid and inositol phosphates in raw flours and infant cereals: The effect of processing

Inositol phosphate modification in infant cereals was examined during industrial processing which included roasting and alpha-amylase treatment. A considerable (p<0.05) decrease in phytate content was observed after both treatments in all the samples analysed. However, the industrial processing observed was not sufficient to cause degradation of the phytate to achieve phytate mineral ratios optimal for mineral absorption in infant cereals. All samples analysed had a phytate/iron molar ratio >1.3, and of the 6 samples, 5 had a phytate/zinc molar ratio >14. The bioavailability of minerals is particularly important during weaning when minerals stores in infants are naturally low. Further studies are needed to evaluate the efficacy and effectiveness of phytase treatment to increase mineral bioavailability in infant foods.     

The supply of bioavailable iron and zinc may be affected by phytate in Beninese children

Food composition data are important for estimating energy and nutrient intakes. The objectives of this study were, first, to evaluate the proximate and inorganic composition of foods eaten in northern Benin and second, to estimate the potentially inhibiting effect of phytate on iron and zinc bioavailability. Chemical analyses were performed in 23 samples of most frequently consumed foodstuffs collected from retailers in local markets. Proximate composition was analysed by routine methods. Inorganic constituents and phytate were analysed using ICP-AES and HPLC. Protein contents were in agreement with those in FAO food composition database. Fat and fibre were in general higher whereas carbohydrate and energy were lower. Differences were mainly due to analytical or calculation methods. The most important sources of iron and zinc in children's diets were maize, sorghum and millet. In these cereals, iron and zinc ranged from 2.6 to 8.4 and 2.2 to 3.4 mg/100 g, respectively. Phytate ranged from 104 to 503 mg/100 g. Phytate/iron and phytate/zinc molar ratios ranged from 1 to 11 and 3 to 22, respectively. They suggest poor iron and zinc bioavailability. Reducing phytate and polyphenol contents in order to improve iron and zinc bioavailability from the most frequently consumed cereal food needs to be studied.     

Availability to rats of zinc in green and mature soybeans

A slope ratio assay was conducted with young albino rats to investigate the effect of maturity of soybean seeds on the bioavailability of their intrinsic zinc. Seeds (Williams) were harvested when well-developed but green (25% dry matter) and when mature (86% dry matter). The blanched seeds were wet-milled, freeze-dried and incorporated into 20% egg white protein diets at the expense of egg white to provide 20% protein diets containing equal calories and calcium but varying in zinc and phytate content. Zinc in the mature bean flour diets was 58% as available for weight gain and 57% as available for tibia zinc accumulation as was zinc in the green bean flour diets. The difference between zinc availabilities can be ascribed to the higher phytate content of the mature beans.     

Bioavailable zinc intake of Korean adults in relation to the phytate content of Korean foods

This study was conducted to create a phytate database for food items and to evaluate the bioavailability of zinc in Korean adults. Eighty-seven food items were analysed. Phytate content was determined by ion exchange method and zinc bioavailability was assessed through a dietary survey of 841 adults. Measured phytate values in various groups were as follows: 191.7–973.3 mg in cereals, 508.5–1371.8 mg in legumes, 0.4–319.9 mg in vegetables, and 1–50 mg in fruits. Mean zinc intakes of Korean adults (9.5 mg for male and 7.5 mg for female subjects) were less than the Korean recommended dietary allowance. Cereals (68.6%) and legumes (19.3%) supplied the most dietary phytate. Mean phytate:zinc ratios were 9.5 for males and 10.5 for females. High zinc bioavailability (phytate:zinc molar ratio below 5) occurred in 9.6% of subjects, whereas 13.2% had low bioavailability (molar ratio over 15). Below-normative zinc intake levels occurred in 54.3% of subjects (61.8% for male and 49.5% for female). Further studies should be directed towards increasing zinc intake and enhancing bioavailability to improve zinc status in Korea.     

Dimensions of Sandawe diet

Rural African children consuming plant‐based diets low in animal products are at risk for sub‐optimal zinc nutriture. Consequently, we investigated indigenous dietary strategies for inproving the zinc nutriture of rural southern Malawian and Ghanaian children.

Seasonal dietary intakes, and the portion sizes of foods consumed by 4–6 year old Malawian and Ghanaian girls (n = 112) were determined from 3‐day weighed food records. The optimal combination of food items for enhancing zinc bioavailability was determined by comparing the zinc content, and the phytate‐to‐zinc molar ratio (PZ) of isocaloric meals and snacks consumed by these girls. The energy content and portion sizes of the recommended meals and snacks were based on actual average intakes.

Results showed that in Malawi the amount of available zinc could be enhanced by using refined corn flour nsima or a non‐traditional fermented corn dough nsima with relishes prepared from small fish, and snacks with moderate to low PZ. In Ghana, fermented corn dough banku, or cocoyam, for root‐based meals, together with a soup/stew of small fish, and zinc‐dense snacks were recommended.     

Complementary feeding practices and dietary intakes from complementary foods amongst weanlings in rural Malawi

OBJECTIVE: The objectives of this study were to estimate the quantity and nutritive quality of the complementary diet in rural Malawi, and to identify feeding practices, nutrients and dietary modifiers of iron and zinc bioavailability that may limit the quality of the diet. DESIGN: This cross-sectional study design included an anthropometric survey, a feeding practices questionnaire, and an interactive, 24 h recall dietary data survey. SETTING: Four rural villages in Balaka district, southern Malawi. SUBJECTS: Mothers resident in the study communities with breastfed children aged up to 24 months were eligible. RESULTS: Stunting was prevalent among these weanlings. Maize was the predominant food source, with limited contribution of animal foods. Deficits in dietary energy and several nutrients were found when compared to estimated needs. When expressed per kg body weight, energy intakes appeared adequate. The bioavailability of zinc was low due to a high phytate:zinc molar ratio. Iron bioavailability was also low due to low intake of absorption enhancers such as meat/fish/poultry protein and ascorbic acid. Dietary quality was poorest for 6 to 8-month-old infants. CONCLUSIONS: Iron, zinc and calcium were the most limiting nutrients to the quality of the diet, partly exacerbated by the poor bioavailability of iron and zinc. Increased total intake and bioavailability of iron and zinc would improve the complementary diets. SPONSORSHIP: This study was funded by the Thrasher Research Fund, Salt Lake City, Utah, USA.     

Improving the bioavailability of nutrients in plant foods at the household level

Plant foods are the major staples of diets in developing countries, in which the consumption of animal-source foods is often low because of economic and/or religious concerns. However, such plant-based diets are often associated with micronutrient deficits, exacerbated in part by poor micronutrient bioavailability. Diet-related factors in plant foods that affect bioavailability include: the chemical form of the nutrient in food and/or nature of the food matrix; interactions between nutrients and other organic components (e.g. phytate, polyphenols, dietary fibre, oxalic acid, protein, fat, ascorbic acid); pretreatment of food as a result of processing and/or preparation practices. Consequently, household strategies that reduce the content or counteract the inhibiting effects of these factors on micronutrient bioavailability are urgently needed in developing-country settings. Examples of such strategies include: germination, microbial fermentation or soaking to reduce the phytate and polyphenol content of unrefined cereal porridges used for young child feeding; addition of ascorbic acid-containing fruits to enhance non-haem-Fe absorption; heating to destroy heat-labile anti-nutritional factors (e.g. goitrogens, thiaminases) or disrupt carotenoid-protein complexes. Such strategies have been employed in both experimental isotope-absorption and community-based studies. Increases in Fe, Zn and Ca absorption have been reported in adults fed dephytinized cereals compared with cereals containing their native phytate. In community-based studies in rural Malawi improvements in dietary quality and arm-muscle area and reductions in the incidence of anaemia and common infections in young children have been observed.     

Consumption pattern, biochemical composition and nutritional value of fermented pearl millet gruels in Burkina Faso

Ben-kida and ben-saalga are popular pearl-millet-based fermented gruels in Burkina Faso. A survey of 318 households in Ouagadougou (Burkina Faso) showed that they are often used as complementary food for young children. Pearl millet and gruels, sampled in 48 production units, were analysed for proximate composition, factors reducing nutrient bioavailability (phytate, insoluble fibres and iron-binding phenolic compounds), alpha-galactosides, sugars, total lactic acid and d-lactic acid, zinc and iron contents. The effects of processing of pearl millet into fermented gruel are discussed. Both positive effects (e.g. a decrease in factors reducing nutrient bioavailability or alpha-galactosides) and undesirable effects (e.g. considerable lipid, protein, iron and zinc losses) were observed. Lactic acid was produced during processing and d(-)-lactate was detected in all samples. The gruels had very low energy density, even after addition of sugar, and low lipid, protein and mineral contents, well below recommendations for complementary foods.     

Consumption pattern,biochemical composition and nutritional value of fermented pearl millet gruels in Burkina Faso

Ben-kida and ben-saalga are popular pearl-millet-based fermented gruels in Burkina Faso. A survey of 318 households in Ouagadougou (Burkina Faso) showed that they are often used as complementary food for young children. Pearl millet and gruels, sampled in 48 production units, were analysed for proximate composition, factors reducing nutrient bioavailability (phytate, insoluble fibres and iron-binding phenolic compounds), α-galactosides, sugars, total lactic acid and d-lactic acid, zinc and iron contents. The effects of processing of pearl millet into fermented gruel are discussed. Both positive effects (e.g. a decrease in factors reducing nutrient bioavailability or α-galactosides) and undesirable effects (e.g. considerable lipid, protein, iron and zinc losses) were observed. Lactic acid was produced during processing and d(?)-lactate was detected in all samples. The gruels had very low energy density, even after addition of sugar, and low lipid, protein and mineral contents, well below recommendations for complementary foods.     

Fermentation of soybean flour with Aspergillus usamii improves availabilities of zinc and iron in rats

Soybean flour was fermented with Aspergillus usamii to improve the availabilities of dietary zinc and iron through the degradation of phytate. Three kinds of experimental diets that differed in protein sources were prepared: one consisting of 40% fermented soybean flour (RS diet), one consisting of 40% fermented soybean flour (FS diet), and one consisting of 20% regular soybean flour and 20% fermented soybean flour (RF diet). Zinc solubilities in the upper and the lower segments of the small intestine were higher in rats fed the FS diet than in rats fed the RS diet. The FS group showed higher solubility of iron in the lower small intestine than the RS group did. Zinc concentrations in the femur and plasma and iron concentrations in the liver and plasma were higher in the FS group than in the RS group. These results suggested that the fermentation of soybean flour improved the availabilities of dietary zinc and iron, which may be induced by increasing the solubilities of these minerals in the small intestine through the reduction of phytate content. Femoral and plasma zinc concentrations in the RF group were higher than in the RS group, but lower than in the FS group. No difference was noted in liver and plasma iron concentrations between the RF group and the FS group. Although phytase activity in FS degrades phytate in the RF diet, higher activity may be needed to degrade phytate completely.     

Maize Porridge Enriched with a Micronutrient Powder Containing Low-Dose Iron as NaFeEDTA but Not Amaranth Grain Flour Reduces Anemia and Iron Deficiency in Kenyan Preschool Children

Few studies have evaluated the impact of fortification with iron-rich foods such as amaranth grain and multi-micronutrient powder (MNP) containing low doses of highly bioavailable iron to control iron deficiency anemia (IDA) in children. We assessed the efficacy of maize porridge enriched with amaranth grain or MNP to reduce IDA in Kenyan preschool children. In a 16-wk intervention trial, children (n = 279; 12-59 mo) were randomly assigned to: unrefined maize porridge (control; 4.1 mg of iron/meal; phytate:iron molar ratio 5:1); unrefined maize (30%) and amaranth grain (70%) porridge (amaranth group; 23 mg of iron/meal; phytate:iron molar ratio 3:1); or unrefined maize porridge with MNP (MNP group; 6.6 mg iron/meal; phytate:iron molar ratio 2.6:1; 2.5 mg iron as NaFeEDTA). Primary outcomes were anemia and iron status with treatment effects estimated relative to control. At baseline, 38% were anemic and 30% iron deficient. Consumption of MNP reduced the prevalence of anemia [-46% (95% CI: -67, -12)], iron deficiency [-70% (95% CI: -89, -16)], and IDA [-75% (95% CI: -92, -20)]. The soluble transferrin receptor [-10% (95% CI: -16, -4)] concentration was lower, whereas the hemoglobin (Hb) [2.7 g/L (95% CI: 0.4, 5.1)] and plasma ferritin [40% (95% CI: 10, 95)] concentrations increased in the MNP group. There was no significant change in Hb or iron status in the amaranth group. Consumption of maize porridge fortified with low-dose, highly bioavailable iron MNP can reduce the prevalence of IDA in preschool children. In contrast, fortification with amaranth grain did not improve iron status despite a large increase in iron intake, likely due to high ratio of phytic acid:iron in the meal.     

Phytate intake and molar ratios of phytate to zinc, iron and calcium in the diets of people in China

OBJECTIVE: To assess the phytate intake and molar ratios of phytate to calcium, iron and zinc in the diets of people in China. DESIGN: 2002 China Nationwide Nutrition and Health Survey is a cross-sectional nationwide representative survey on nutrition and health. The information on dietary intakes was collected using consecutive 3 days 24 h recall by trained interviewers. SUBJECTS: The data of 68 962 residents aged 2-101 years old from 132 counties were analyzed. RESULTS: The median daily dietary intake of phytate, calcium, iron and zinc were 1186, 338.1, 21.2 and 10.6 mg, respectively. Urban residents consumed less phytate (781 vs 1342 mg/day), more calcium (374.5 vs 324.1 mg/day) and comparable amounts of iron (21.1 vs 21.2 mg/day) and zinc (10.6 vs 10.6 mg/day) than their rural counterparts. A wide variation in phytate intake among residents from six areas was found, ranging from 648 to 1433 mg/day. The median molar ratios of phytate to calcium, iron, zinc and phytate x calcium/zinc were 0.22, 4.88, 11.1 and 89.0, respectively, with a large variation between urban and rural areas. The phytate:zinc molar ratios ranged from 6.2 to 14.2, whereas the phytate x calcium/zinc molar ratios were from 63.7 to 107.2. The proportion of subjects with ratios above the critical values of phytate to iron, phytate to calcium, phytate to zinc and phytate x calcium/zinc were 95.4, 43.7, 23.1 and 8.7%, respectively. All the phytate/mineral ratios of rural residents were higher than that of their urban counterparts. CONCLUSIONS: The dietary phytate intake of people in China was higher than those in Western developed countries and lower than those in developing countries. Phytate may impair the bioavailability of iron, calcium and zinc in the diets of people in China.     

Phytate,zinc, iron and calcium content of selected raw and prepared foods consumed in rural Sidama,Southern Ethiopia,and implications for bioavailability

Representative staple foods from Sidama, Southern Ethiopia, were analyzed for phytate using HPLC, and for Zn, Fe and Ca by flame atomic absorption spectrophotometry (AAS). Enset starchy foods had the lowest phytic acid content, followed by fermented injera prepared from tef. Oleaginous seeds (niger and sesame) had the highest phytate content (∼1600 mg/100 g). The iron content of raw tef and tef injera, unlike barley flour or corn bread, varied markedly, attributed to contaminant iron from soil. The foods prepared from enset and tef were also rich sources of calcium. Most of the fermented foods prepared from enset and tef had low Phy:Zn and Phy:Fe molar ratios, whereas corn bread (unleavened), kidney beans, sesame, and niger seeds had higher molar ratios. Absorption of intrinsic Zn, Fe, and Ca as well as any exchangeable contaminant iron is unlikely to be compromised by phytate in the fermented foods prepared from enset and tef, unless consumed together with high phytate foods such as corn bread, legumes, and oil seeds.     

Contribution to the improvement of a porridge made with fermented maize: effect of selected foods and lemon on energy density, pH, viscosity and nutritional quality

The objective of the present study was to use lemon and selected foods to improve the nutritional characteristics, quality and the nutrient content of a traditional complementary porridge made of lactic acid fermented yellow maize. Boiled egg yolk, roasted peanut paste, dry crayfish flour, roasted soybean flour and lemon juice were used as food additions. Amounts of food added were calculated on the basis of World Health Organization estimated energy needs from complementary foods of well-nourished children in developing countries, aged 9-11 months, at four servings per day and a low amount of breast milk energy. The pH and viscosity increased in porridges with food addition, but lemon juice contributed to lowering them. Energy and nutrient densities/100?g porridge improved with food addition regardless of the use of lemon juice. An increase in iron, zinc and calcium in vitro availability was observed (P?相似文献