2008 Volume 25 Pages 46-50
We previously prepared a hot water extract and a zinc-rich fraction from oyster and investigated the utilization of zinc from oysters. In the present study, a new oyster extract prepared from a mixture of the hot water extract and the zinc-rich fraction was examined in rats. In experiment 1, changes in the absorption rate and tissue distribution of zinc were examined under different level of sodium phytate administration. Five-week-old male Wistar rats were given diets containing 20 ppm of zinc as zinc sulfate for 29 days ; those diets were replaced and supplemented with graded levels (0 %, 0.2 %, 0.5 %, 1.0 % or 2.0 %) of sodium phytate. The rats fed a diet higher in sodium phytate showed lower tissue zinc concentrations in several tissues. In particular, the zinc concentrations in serum, tibia, ileum and hair responded remarkably to the declination in dietary sodium phytate. There was a negative linear relationship between zinc concentrations in the tissues (serum, tibia, ileum and hair) and dietary sodium phytate level from 0 % to 1.0 %. In experiment 2, effects of differences in zinc source on the absorption and tissue distribution of zinc in rats fed a diet containing sodium phytate were examined. Five-week-old male Wistar rats were given 1.0 % sodium phytate-supplemented diet containing 20 ppm of zinc as zinc sulfate or 3 types of oyster extracts for 29 days. Differences in dietary zinc source (zinc sulfate or oyster extract) did not significantly influence zinc concentrations in serum or various other tissues. The rats fed a diet containing zinc as a new oyster extract showed slightly higher zinc concentrations in several tissues (serum, tibia and ileum) than those fed a diet containing zinc as zinc sulfate or other oyster extracts. These findings suggest that the new oyster extract has higher zinc bioavailability than zinc sulfate or other oyster extracts.
