Nutrition, Physical Activity, and Quality of Life in Older Adults: Summary

Abstract

WE live in an aging society. Not only is 1 in every 8 Americans older than 65 years, but a person aged 65 can expect to live an average of 18 more years (1). People aged 85 years and over are the fastest-growing group, and the proportion of these “oldest old” is expected to triple between now and year 2030 (2). Continued good health of the elderly population is a major challenge to public health (3). Increased longevity is associated with an increase in multiple chronic conditions that sometimes translate into functional disability and need for assistance (2). The extra years can be marked by declining health, reduced mobility, depression, isolation, and loneliness (4). Health and functioning of older adults are influenced by many factors other than biological senescence. Demographic, social, and environmental factors, including physical activity and dietary habits, play a major role. Fortunately, many of these societal factors are amenable to public health interventions and programs (5). More than any other age group, older adults are seeking health information and are willing to make behavioral changes to maintain their health and independence into advanced old age (1). Among the most important self-care behaviors are those that involve physical activity and diet. Their contribution to health and quality of life is the principal topic of this review. In many past studies the success of the efforts at health promotion has been measured in terms of lower mortality rates or reduced disease risk. There is increasing concern that these classic medical endpoints (mortality and morbidity) may not adequately represent functional impairments and disabilities during the later years of life. Increasingly, health is viewed as not only the absence of infirmity and disease but also as a state of physical, mental, and social well-being (6)(7). Much progress has been made in establishing a broader conceptual framework of health status for older adults (8). Indexes of health-related quality of life (HRQL), a relatively new concept, expand the morbidity- and mortality-based definition of health to include a personal sense of physical and mental health, social functioning, and emotional well-being. Other and more global measures of quality of life are even more inclusive, taking overall life satisfaction and happiness into account (9)(10). Quality-of-life measures permit researchers to compare the status of different groups over time and assess the effectiveness of public health interventions and programs (2)(7). However, the effectiveness of diet and exercise programs continues to be measured in terms of biomedical endpoints. Many of the existing quality-of-life indexes do not directly address the contribution of either physical activity or diet. Very few studies have explored the interrelationships among dietary measures, physical activity variables, and quality-of-life indexes in older adults or the nature of the intervening variables. As documented below, such factors as perceived mastery and control, enjoyment of the diet, or satisfaction with exercise programs may be as important to quality of life as is reduced plasma cholesterol or increased grip strength. This monograph summarizes what we know about age-associated changes in activity levels and eating habits and suggests how these factors may be related to quality of life. Healthy life means a full range of functional capacity at each life stage, from infancy to old age (1). Some age-related changes involve a gradual decline in function that is due to biological senescence (11). For example, aging is generally associated with more body fat and reduced muscle mass (12)(13). Reduced muscle mass has been directly linked with lowered muscle strength, lowered maximal aerobic capacity, and decreased bone density in elderly adults (12). However, not all age-associated changes are caused by age alone. Some scientists believe that the age-associated decline in function is caused by cumulative exposure to risk factors rather than only by aging (2)(14). For example, lower insulin sensitivity and increased risk of type 2 diabetes are also influenced by genetics, body composition, and sedentary lifestyles (15). Very little, if any, of the age-associated change in glucose tolerance is caused by age alone (15). Age-associated changes in metabolism or physiological function may be partly responsible for the observed decline in energy intakes as well as for shifts in dietary choices and eating habits (16). Reduced muscle mass results in lower energy requirements. As noted by Morley (16), aging has been associated with altered sensations of thirst, hunger, and satiety and with incomplete adjustments for day-to-day variations in food intake. The observed deficits in taste and smell may lead to a reduced sensory enjoyment of foods by elderly adults (4). The lack of sensory-specific satiety (a variety-seeking mechanism) may explain why some elderly people restrict food choices and adop