407.

Solomons NW, Jacob RA, Pineda O, Viteri FE. Studies on the bioavailability of zinc in man. Effects of the Guatemalan rural diet and of the iron-fortifying agent, NaFeEDTA. J Nutr. 1979; 109(9):1519-1528. (NA50) [By serial estimation of the change in plasma zinc concentration after a standard dose of 110 mg zinc sulphate heptahydrate, containing 25 mg elemental Zn, the biological availability of Zn was evaluated in human subjects. Plasma Zn concentration was stable in the fasting state. After the standard dose of Zn, 25 mg in water, plasma Zn increased above the fasting, baseline values of 61.0, 68.0, 52.0 and 37.8 mg/100 ml, respectively, at the first 4 hourly sampling intervals. Four h after a standard meal, based on the traditional rural diet of Guatemala and consisting of 120 g maize tortillas, 120 g black bean gruel, 40 g sweet rolls and 250 ml coffee sweetened with 15 g sugar, plasma Zn was significantly lower than the fasting value. Addition of 25 mg Zn to the black bean gruel in the meal prevented this decline, but did not increase plasma Zn above fasting values; apparently Zn absorption was inhibited by the meal. Probably, phytates, dietary fibre and calcium were major factors, and coffee was a minor factor in this inhibition. The chelate of iron with EDTA, NaFeEDTA, an Fe-fortifying agent proposed for use in Guatemala, at 15 mg, equivalent to that in a cup of coffee sweetened with 15 g fortified sugar, and at 40 mg, equivalent to that eaten in a day by rural Guatemalans, did not significantly depress Zn uptake. Moreover, no influence of 15 mg NaFeEDTA beyond that of coffee or food itself, was found. High doses of NaFeEDTA, beyond the normal range, impaired Zn absorption, and the EDTA moiety, rather than Fe, was responsible. The suggestion was that fortification of sugar with NaFeEDTA at 1 mg/g would not influence Zn status, but that the basal Guatemalan diet, itself, impairs Zn status.]

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