Copper absorption fiber-containing diets

Table IV. Zinc and copper absorption from diets containing phytate and fiber.

I he RDA for zinc is 15 mg. With mixed diets containing phytate and fiber, about 30% of dietary zinc Is absorbed. The efficiency of absorption increases with diets containing very little zinc. Dietary zinc must replace the obligatory losses, which, at the minimum, are about 0.7 mg/day. The RDA for copper has not been determined. The National Research Council recommends 1.5 to 3.0 mg per day as a safe and adequate range of dietary copper intake for adults. The usual dietary intake of copper in the United States is about 1 mg/day. This amount is sufficient to... 

Dietary fiber and phytate. Dietary fiber and phytate are known as potential inhibitors of the absorption of divalent cations however, the literature regarding the effect of dietary fiber and phytate on the bioavailability of minerals is contradictory. Data by Yannai and Sachs (1993) indicate that phytate does not affect methylmercury absorption. Yannai and Sachs (1993) compared the absorption by rats of mercury found intrinsically in experimental fish meal with and without added phytate and found no significant differences in the absorption of Hg (93 5%) between 2 experimental fish meal diets (containing 1.4 mol Hg/kg diet), with or without added sodium phytate. The authors speculated that phytate might be preferentially bound to zinc, iron, and copper, which were present at much higher concentrations in the diet. 

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