Oyster shell heated in vacuo, mainly consisting of calcium oxide (CaO), is nonirritating and highly absorbable from the intestine . The effects of oyster shell heated in vacuo on hematological and biochemical data and duration of survival of rats were compared with those of commonly used calcium carbonate (CaCO 3) . Ninety rats were divided into three groups and given a diet containing 1 % calcium as CaCO3 from the 10th week after birth until natural death (group A), a mixture of heated oyster shell and calcium carbonate in equal amounts (group B), and heated oyster shell (group C) . Hematological values and serum components such as total protein, albumin, albumin/globulin (A/G) ratio, GOT, GPT, alkaline phosphatase, total cholesterol, free cholesterol, triglycerides, urea nitrogen, creatinine, Na, K, and Ca were measured up to the 65th week . Following natural death, autopsy was performed. The results were as follows : Animals on oyster shell heated in vacuo tended to show milder anemia and leukocytosis, significantly higher serum albumin, and lower GPT, with a tendency of lower total and free cholesterol, urea nitrogen, and creatinine . The mean survival was 618 ± 22 days in group A, 665 ±-24 in group B and 685 ± 20 in group C (mean ± SEM), suggesting a longer survival on supplementation with heated oyster shell . Autopsy revealed less frequent ocurrence of tumors and nephrosclerosis in heated oyster shell-supplemented rats . These results support the hypothesis that oyster shell heated in vacuo is more beneficial for the metabolism and survival of rats than CaCO3 , possibly through its high biological availability . Key words: calcium supplementation, life-span, oyster shell heated in vacuo, calcium carbonate, serum protein Offprint requests to : Takuo Fujita Bone and Mineral Metabolism © Springer-Verlag 1995 Effect of calcium supplementation as oyster shell heated in vacuo on metabolism and survival of rats TAKUO FUJITA', RIKO KITAZAWA 2 , MASAAKI FUKASE3 , KIYOHISA UCHIDA4 , SABURO MATSUDA 4, and TAKESHI NAKAI 4
