Abstract
It is estimated that one fourth of Japan's population in the 21st century will be older than 65 years of age. Accompanying this increased percentage of elderly people will be an increased incidence of life-style-related diseases and infectious diseases associated with the reduced cellular immunity that occurs during aging. If this decrease of cellular immunity can be minimized, it might improve the health of older persons and prolong life expectancy. This paper summarizes the effect of nutrition and exercise on decreased cellular immunity in the aged. Obesity (BMI>30) in the aged induced marked decreases of T cell proliferation following in vitro activation with PHA or Con A and natural killer cell (NK) activity. In contrast, exercise training improved not only the decreased phagocytic activity but also the responsiveness to macrophage-activating factor (MAF) produced from activated T cells among alveolar macrophages (AM) in aged rats (24 months old). In addition, reduction in the activities of daily life (ADL) was closely associated with decreased NK activity in elderly people admitted to health service facilities for the aged. In conclusion, this study suggests that obesity is one of the risk factors for deteriorating health in the aged, and that maintenance of physical activity in the aged is important for retaining cellular immunity in this population group.
