A Review of Phytate, Iron, Zinc, and Calcium Concentrations in Plant-Based Complementary Foods Used in Low-Income Countries and Implications for Bioavailability

Department of Human Nutrition, University of Otago, Union Street, PO Box 56, Dunedin 9015, New Zealand.
Food and nutrition bulletin (Impact Factor: 1.15). 06/2010; 31(2 Suppl):S134-46. DOI: 10.1177/15648265100312S206
Source: PubMed


Plant-based complementary foods often contain high levels of phytate, a potent inhibitor of iron, zinc, and calcium absorption. This review summarizes the concentrations of phytate (as hexa- and penta-inositol phosphate), iron, zinc, and calcium and the corresponding phytate:mineral molar ratios in 26 indigenous and 27 commercially processed plant-based complementary foods sold in low-income countries. Phytate concentrations were highest in complementary foods based on unrefined cereals and legumes (approximately 600 mg/100 g dry weight), followed by refined cereals (approximately 100 mg/100 g dry weight) and then starchy roots and tubers (< 20 mg/100 g dry weight); mineral concentrations followed the same trend. Sixty-two percent (16/26) of the indigenous and 37% (10/27) of the processed complementary foods had at least two phytate:mineral molar ratios (used to estimate relative mineral bioavailability) that exceeded suggested desirable levels for mineral absorption (i.e., phytate:iron < 1, phytate:zinc < 18, phytate:calcium < 0.17). Desirable molar ratios for phytate:iron, phytate:zinc, and phytate:calcium were achieved for 25%, 70%, and 57%, respectively, of the complementary foods presented, often through enrichment with animal-source foods and/or fortification with minerals. Dephytinization, either in the household or commercially, can potentially enhance mineral absorption in high-phytate complementary foods, although probably not enough to overcome the shortfalls in iron, zinc, and calcium content of plant-based complementary foods used in low-income countries. Instead, to ensure the World Health Organization estimated needs for these minerals from plant-based complementary foods for breastfed infants are met, dephytinization must be combined with enrichment with animal-source foods and/or fortification with appropriate levels and forms of mineral fortificants.

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Available from: Michelle Gibbs, May 24, 2015
    • "Although the polyphenol content of these meal plan models was not measured, the phytic acid content was analyzed using a quantitative colorimetric method to measure the total available phosphorus released from the plant seeds. The phytic acid concentration of the meals was higher than that of lentils alone, but within the range of other staple food crops[4,13,21,22]. Dehulling appeared to make phytic acid more available, but the improved relative iron bioavailability in the dehulled meals overcame this increase in phytic acid. "
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    ABSTRACT: Background. Iron deficiency is the most common nutrient deficiency worldwide. Large intakes of micronutrient-poor staple crops, coupled with low intakes of highly bioavailable dietary iron, are a major cause of this deficiency.Objective. To examine the concentration and relative bioavailability of iron in several models (n = 23) of traditional Bangladeshi meals (rice, lentils/dal, vegetable, and fish), as well as the effect of removal of the lentil seed coat on the nutritional quality of iron.Methods. The relative bioavailability of iron was assessed by the in vitro/Caco-2 cell culture method, iron concentration by an inductively coupled argon-plasma emission spectrometer (ICAP-ES), and phytic acid concentration by colorimetric assay. The recipes contained 75% to 85% rice, 0% to 15% dal (containing whole or dehulled lentils), 0% to 15% vegetable curry, and 0% to 8% fish.Results. While the iron concentrations of recipes containing dehulled dal were significantly lower than those of recipes containing whole dal (p = .005), seed coat removal doubled relative iron bioavailability and increased phytic acid concentration (p r = 0.48, p = .03), but not whole dal (r = – 0.047, p = .84).Conclusions. The total amount of iron absorbed from traditional Bangladeshi meals is dependent upon iron concentration, and dehulling lentils removes inhibitory factors increasing iron uptake but also increases the density of phytic acid in the lentil sample. Thus, along with breeding for high iron concentration and bioavailability (i.e., biofortification), seed coat removal plus measures to lower phytic acid concentrations may be an important strategy to improve the bioavailability of iron in lentils and other pulse crops.
    No preview · Article · Dec 2014 · Food and nutrition bulletin
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    • "The total contents of Fe, Zn, Ca and Mg in a given food product are not the only criteria determining its nutritional quality, as it also depends on their bioavailability from that product. In order to determine whether a product is a good source of a particular mineral, it is necessary to determine the amount of that mineral released or absorbed in the animal or human organism (Gibson et al. 2010). There are various in vitro and in vivo methods to determine bioaccessibility of minerals (Skibniewska et al. 2002). "
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    ABSTRACT: The objective of this study was to determine the content and the bioaccessibility of minerals (Fe, Zn, Ca and Mg) in commonly consumed food products, such as cereal groats, rice, leguminous grains and nuts purchased from the local market. The contents of Fe, Zn, Ca and Mg in foods were assayed after dry ashing of samples, while the bioaccessibility of these minerals after enzymatic in vitro digestion, was determined by flame atomic absorption spectrometry. A relatively high content of Fe was found in cashew nuts and green lentils, while cashew nuts and buckwheat groats had the highest concentration of Zn. It was found that the highest amount of macro-elements was generally in nuts, in particular: brazil nuts (Ca and Mg), cashews (Mg) and hazelnuts (Ca and Mg). Concerning the mineral bioaccessibility, the highest values for Fe were obtained in cashew nuts and green lentils (2.8 and 1.7 mg/100 g), for Zn in green lentils (2.1 mg/100 g), for Ca in brazil nuts and shelled pea (32.6 and 29.1 mg/100 g), while for Mg in shelled peas and green lentils (43.4 and 33.9 mg/100 g). Generally, the best sources of bioaccessible minerals seem to be leguminous grains and nuts.
    Full-text · Article · Mar 2014 · Journal of Food Science and Technology -Mysore-
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    • "This illustrates that transitioning directly to “family foods” as the sole source of complementary foods may put the infant at risk of multiple micronutrient deficiencies. Even when “improved” complementary food recipes are developed, they usually fall short of providing adequate iron, zinc, and sometimes calcium (11). "
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    ABSTRACT: Breast-fed infants and young children need complementary foods with a very high nutrient density (particularly for iron and zinc), especially at ages 6-12 mo. However, in low-income countries, their diet is usually dominated by cereal-based porridges with low nutrient density and poor mineral bioavailability. Complementary feeding diets typically fall short in iron and zinc and sometimes in other nutrients. These gaps in nutritional adequacy of infant diets have likely been a characteristic of human diets since the agricultural revolution ∼10,000 y ago. Estimates of nutrient intakes before then, based on hypothetical diets of preagricultural humans, suggest that infants had much higher intakes of key nutrients than is true today and would have been able to meet their nutrient needs from the combination of breast milk and premasticated foods provided by their mothers. Strategies for achieving adequate nutrition for infants and young children in modern times must address the challenge of meeting nutrient needs from largely cereal-based diets.
    Preview · Article · Oct 2013 · Journal of Nutrition
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