Copper(Cu)is related intimately to oxygen stress and its detoxication, that is prooxidant and antioxidant. Oxygen stress can make aging process accelerate. Therefore it is important to clarify the relationship between Cu metabolism and aging. The amounts of body Cu are the following orders of bone > muscle > liver > brain. The absorption of dietary Cu is carried out mainly in the proximal portion of small intestine. After absorption Cu is transferred to the target proteins and organelles by both transporters and chaperones of Cu. By gene deficit severe hypocupremia occurs in patients with Wilson disease or with Menkes disease, resulting in some prominent features of Cu deficiency. Cu proteins play a pivotal role in cellular metabolism through enzyme activities and in ameliorating oxygen stress. During 6 years from 1997 to 2002 Cu-poor enteral liquid foods were used in elderly inpatients with cerebrovascular disease, resulting in severe hypocupremia after about 6 months. Then Cu-rich ones were recently administered to inpatients, resulting in normocupremia from hypocupremia after about 4 months. The administration of L-8 enteral liquid food(Asahi-kasei Pharma)could maintain in the normal range of serum Cu and ceruloplasmin(Cp)during 21 months, which contained 0.8 mg of Cu per 1,000 kcal and might be fulfilled with adequate intakes of Cu. In elderly inpatients with extremely low levels of serum Cu below 10 µg/dl(normal range 70 - 132 µg/dl)leucopenia, neutropenia and anemia were detected, which could be improved by Cu supplementation. By bone biopsy and aspiration in one woman aged 45 years, increments of both myelocytes and erythroid cells are found, indicating a disturbance of maturity, of which cytoplasma involves vacuole degeneration. In clinical investigations of both sexes normocupremia was obtained from hypocupremia by enteral liquid foods with mean 0.69 mg of daily Cu intake, and with 0.8 mg of daily Cu for 24 months. Normocupremia was maintained during 21 months, when male elderly inpatients received mean 0.96 mg of Cu intake and female ones did mean 0.8 mg of Cu intake. Therefore, an adequate Cu intake can be estimated to be 0.69 mg to 0.96mg daily in elderly inpatients with tube feeding, corresponding with 0.7 mg to 0.8 mg of Cu recommendation of Japan in 2005. About inflammation serum Cu and Cp levels are parallel to serum CRP. The length of lifespan from beginning of tube feedings was longer significantly in female elderly inpatients with normocupremia as compared to female ones with hypocupremia, indicating a novel antiaging effect of normocupremia due to adequate Cu intake.