A review of phytate, iron, zinc, and calcium concentrations in plant-based complementary foods used in low-income countries and implications for bioavailability.
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.
Gibson
Rosalind S
RS
Department of Human Nutrition, University of Otago, Union Street, PO Box 56, Dunedin 9015, New Zealand. Rosalind.Gibson@Stonebow.Otago.AC.NZ
Bailey
Karl B
KB
Gibbs
Michelle
M
Ferguson
Elaine L
EL
D002136:Calcium, Dietary / Q000032:analysis* / Q000378:metabolism; D003906:Developing Countries; D002523:Edible Grain / Q000737:chemistry; D007887:Fabaceae / Q000737:chemistry; D005524:Food Technology; D005527:Food, Fortified / Q000032:analysis; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000032:analysis*; D019266:Iron, Dietary / Q000032:analysis* / Q000378:metabolism; D009753:Nutritive Value; D010833:Phytic Acid / Q000032:analysis* / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry; D010945:Plants, Edible / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry; D015032:Zinc / Q000032:analysis* / Q000378:metabolism
D002136:Calcium, Dietary; D019266:Iron, Dietary; D010833:Phytic Acid; D015032:Zinc