Nutrition-related problems of middle age.

In a review of nutrition and ageing (Munro, 1981), it was suggested that research on this topic can be divided into three headings. First, there are the changes in body composition and physiological function that occur progressively throughout adult life. In most cases it is uncertain whether these processes are responsive to nutritional status. Second, some chronic diseases and disabilities of adults increase with age; in some cases, such as atherosclerosis, there is controversial evidence relating the progress of this condition to nutrient intakes. Finally, there is the tendency of adults to reduce their total food intake progressively as they get older. This usually results in diminished intakes of most nutrients. In most cases, our ignorance of the needs of adults for individual nutrients as they get older does not allow us to say whether this reduction in intake falls below the amount necessary to maintain optimum body function. This paper will deal with each of these aspects of the ageing process. It will emphasize that middle age is a time to establish health-related habits (including nutritional) in preparation for old age. Although emphasis tends to be placed on the age-associated diseases of adults (atherosclerosis, cancer, etc.), the progressive erosion of tissue function, though less dramatic, is commonly responsible for the eventual disabling of the individual. Katz et al. (1983) have recently used life-table techniques to estimate the expected years of functional well-being remaining to residents of Massachusetts at various ages from 65 years onwards. Using the criteria of unassisted rising from bed, bathing, dressing and eating, they found that men of 65-69 years averaged 9.3 more years of independent living and a further 3.8 years of dependence, while for women of 65-69 years there remained 10.6 years of independent living and 8.9 years of dependence. An important question is thus the extent to which life-style factors, including nutrition, during the period preceding old age can extend the period of independent living.