The average life span of the Japanese has grown to 75.61 years for men and 81.39 years for women: both Japanese men and women have the longest life spans of any peoples in the world. The Welfare Ministry has urged a review of the social security system including medicine and pensions, and is seeking to establish lives worth living in our old age for the coming aging society, because there is no sign of the increase in the average life span slowing down. Various functions of the living body change physiologically with aging. Figure 1 shows a well-known graph showing "Changes in Physiological Functions with Aging" reported by Shock in 1971. It shows that systemic basic metabolism decreases almost linearly with age after about 30 years that reaches the peak of body functions, as well as almost all autonomic functions, including the kidney, lung, heart, and nerves. The speed at which functions decrease varies with organs. The age when functions begin to decrease differs between individuals. Generally, however, the ability of the eye to adjust makes us aware of aging at the earliest stage of life. The distribution of all elements comprising a body decreases with age, except for extracellular fluid. There are many difficulties in establishing lives worth living in old age, because of the fact that aged people suffer from reduced physiological and physical functions. The pleasure of eating may be one of the things that make life worth living. Many aged people seem to wish that they could enjoy meals as they did in their youth.(ABSTRACT TRUNCATED AT 250 WORDS)