Bioavailability of zinc in coagulated soy protein (tofu) to rats and effect of dietary calcium at a constant phytate:zinc ratio.

An assay was conducted with young albino rats to compare the bioavailability of zinc contained in calcium- and in magnesium-precipitated tofu to zinc supplied as the carbonate in egg white diets. Relative availability of zinc from both tofu preparations was 51% as measured by weight gain and 36-39% for log micrograms tibia zinc accumulation. In a separate experiment with zinc supplied at 9 mg/kg in all diets, the effect of increasing dietary calcium on weight gain and tibia zinc accumulation was tested. Performance of tofu-fed rats relative to zinc carbonate-fed rats at 0.4, 0.7 and 1.2% calcium was, respectively: 92, 67 and 48% for weight gain, and 70, 58 and 61 for tibia zinc content.