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° Massachusetts Institute of Technology, Cambridge, MA 02139
Division of Human Nutrition and Biology, Institute of Nutrition of Central America and Panama, Guatemala City, Guatemala, Apartado 1188
U. S. Department of Agriculture, Science and Education Administration, Grand Forks Human Nutrition Research Center, Grand Forks, ND, 58202.
By serial determination of the change in plasma nickel concentration following a standard dose of 22.4 mg of nickel sulfate hexahydrate condtaining 5 mg of elemental nickel, the bioavailability of nickel was estimated in human subjects. Plasma nickel concentration was stable in the fasting state and after an unlabeled test meal, but after the standard dose of nickel in water was elevated 48.8, 73.0, 80.0, and 53.3 µg/l, respectively, at hours 1, 2, 3, and 4. Plasma nickel did not rise above fasting levels when 5 mg of nickel was added to two standard meals: a typical Guatemalan meal and a North American breakfast. When 5 mg of nickel was added to five beverageswhole cowmilk, coffee, tea, orange juice, and Coca Cola®the rise in plasma nickel was significantly suppressed with all but Coca Cola®. Response to nickel also was suppressed in the presence of 1 g of ascorbic acid. Phytic acid in a 2:1 molar ratio with nickel, however, did not affect the rise in plasma nickel. The chelate of iron and ethylenediaminetetraacetate, NaFeEDTA, an iron-fortifying agent suggested for application in Central America, slightly but significantly depressed plasma nickel rise at 2 hours, whereas disodium EDTA depressed plasma nickel levels significantly below the fasting nickel curve at 3 and 4 hours postdose. These studies suggest that the differential responses of inorganic nickel to distinct foods, beverages, and chemically-defined dietary constitutents could be important to human nutrition.
KEY WORDS: nickel ascorbic acid phytic acid EDTA
1 Presented in part at the Western Hemisphere Nutrition Congress VI, Los Angeles, August, 1980, p. 84 (abstracts).
3 Reprint requests: N. W. Solomons, INCAP, Carretera Roosevelt, Zona 11, Guatemala City, Guatemala, Central America, Apartado 1188.
4 Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable.
5 Abbreviations used: Nickel sulfate = NiSO4·6H2O; ethylenediamine-tetraacetic acid = EDTA; sodium iron ethylenediaminetetraacetic acid = NaFeEDTA; disodium ethylenediaminetetraacetic acid = Na3EDTA. 2H2O.
Manuscript received 8 August 1981.