Abstract
Nagakonbu (Laminaria angustata var. longissima Miyabe) and Okinawa-tofu are frequently consumed by aged persons in Okinawa. In this study the effects of Nagakonbu and Okinawa-tofu on bone metabolism in ovariectomized rat were examined. Six-week-old Wistar-strain female rats were divided into ovariectomized and shamtreated groups. Thereafter a control group was fed a “CaCO3 diet” (0.2% Ca, 0.15% P) and the experimental groups were fed either the “Nagakonbu diet” (0.2% Ca, 0.1% P), or the “Okinawa-tofu diet” (0.2% Ca, 0.2% P) ad libitum for 35 days. The calcium absorption of the ovariectomized rats fed the Okinawa-tofu diet was significantly lower than that of rats fed the CaCO3 or Nagakonbu diets. On the other hand, the calcium content of the left femurs of ovariectomized rats fed the Nagakonbu or Okinawa-tofu diets was significantly higher than those of rats fed the CaCO3 diet. In addition, greater strength, stiffness and toughness (mechanical properties) of the femurs was also observed in Nagakonbu diet-fed rats. These results suggest that Nagakonbu and Okinawa-tofu may be suitable as a source of dietary calcium.
