Elsevier

The Journal of Nutrition

Volume 130, Issue 5, May 2000, Pages 1378S-1383S
The Journal of Nutrition

Dietary Factors Influencing Zinc Absorption1

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Marginal zinc deficiency and suboptimal zinc status have been recognized in many groups of the population in both less developed and industrialized countries. Although the cause in some cases may be inadequate dietary intake of zinc, inhibitors of zinc absorption are most likely the most common causative factor. Phytate, which is present in staple foods like cereals, corn and rice, has a strong negative effect on zinc absorption from composite meals. Inositol hexaphosphates and pentaphosphates are the phytate forms that exert these negative effects, whereas the lower phosphates have no or little effect on zinc absorption. The removal or reduction of phytate by enzyme (phytase) treatment, precipitation methods, germination, fermentation or plant breeding/genetic engineering markedly improves zinc absorption. Iron can have a negative effect on zinc absorption, if given together in a supplement, whereas no effect is observed when the same amounts are present in a meal as fortificants. Cadmium, which is increasing in the environment, also inhibits zinc absorption. The amount of protein in a meal has a positive effect on zinc absorption, but individual proteins may act differently; e.g., casein has a modest inhibitory effect of zinc absorption compared with other protein sources. Amino acids, such as histidine and methionine, and other low-molecular-weight ions, such as EDTA and organic acids (e.g., citrate), are known to have a positive effect on zinc absorption and have been used for zinc supplements. Knowledge about dietary factors that inhibit zinc absorption and about ways to overcome or remove these factors is essential when designing strategies to improve the zinc nutrition of vulnerable groups. J. Nutr. 130: 1378S—1383S, 2000.

Key words:

zinc
zinc absorption
zinc bioavailability
inhibitors
phytate

Abbreviations used:

BSA
bovine serum albumin
CPP
casein phosphopeptides

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1

Presented at the international workshop “Zinc and Health: Current Status and Future Directions,” held at the National Institutes of Health in Bethesda, MD, on November 4–5, 1998. This workshop was organized by the Office of Dietary Supplements, NIH and cosponsored with the American Dietetic Association, the American Society for Clinical Nutrition, the Centers for Disease Control and Prevention, Department of Defense, Food and Drug Administration/Center for Food Safety and Applied Nutrition and seven Institutes, Centers and Offices of the NIH (Fogarty International Center, National Institute on Aging, National Institute of Dental and Craniofacial Research, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute on Drug Abuse, National Institute of General Medical Sciences and the Office of Research on Women's Health). Published as a supplement to The Journal of Nutrition. Guest editors for this publication were Michael Hambidge, University of Colorado Health Sciences Center, Denver; Robert Cousins, University of Florida, Gainesville; Rebecca Costello, Office of Dietary Supplements, NIH, Bethesda, MD.