Academic journal article Annual Review of Gerontology & Geriatrics

Roles of Oxidative Damage, Exercise, and Caloric Restriction in Health Span

Academic journal article Annual Review of Gerontology & Geriatrics

Roles of Oxidative Damage, Exercise, and Caloric Restriction in Health Span

Article excerpt

ABSTRACT

The goal of this chapter is to critically examine the possible contributions of oxidative damage, exercise, and caloric restriction (CR) to health in later life by defining these quantities, discussing experimental studies that suggest their importance for particular measures of health and then evaluating their role in the determination of health span. The timing, duration, and combination of these factors contribute to environment, a major determinant of longevity. Current information indicates that genetic inheritance contributes no more than 35% of an individual's longevity, implying personal choices in lifestyle greatly impact health and health span. Physical activity is known to promote longevity and health, whereas physical inactivity promotes obesity and augments the risk of endocrine, nutritional, and age-associated diseases. The balance of biomarkers of oxidative stress (such as plasma protein carbonyls, nitrotyrosine, and malondialdehyde) and those of antioxidant status (such as oxygen radical absorbance capacity) may provide some indication of health. Individual differences in the physiological function of the inflammatory and heat-shock responses may also impact aging and health span. CR is one of the most robust and reliable means of improving health and performance in old age. This regimen of decreasing food intake has been demonstrated to extend longevity and increase vitality in a wide range of organisms under laboratory conditions. Preliminary results in monkeys and men and women are encouraging for promoting health span, if not life span. However, recent data indicate that genetic background is important in these effects, suggesting caution should be exercised in applying CR in free-living men and women. Compounds capable of inducing such effects without the need to reduce feeding recently have been identified and are in the process of widespread testing. Possibilities for extending the health span using exercise and CR-like effects thus appear promising, but undesirable side effects must also be recognized and accommodated.

INTRODUCTION

Health in late life is the net result of a complex interplay of biological, psychosocial, and environmental factors occurring over a lifetime. Although it is often stated that the best way of living long is to choose one's parents wisely, scientific studies indicate that genetic inheritance contributes no more than 35% of an individual's longevity. The important implication of this result is that other factors, such as the environment, constitute major determinants of length of life. Similar reasoning applies to the duration of active living, or the fraction of the life span in which an individual is sufficiently competent in cognitive and physical domains so as to be able to continue to participate fully in the intellectual and social activities of the community. This period, the health span, is the focus of this chapter. Processes that are currently believed to play a major role in limiting health (or in limiting the maintenance of homeostasis) are defined and examined. In addition, strategies and behaviors that are thought to be effective in promoting health in late life are identified and evidence for their effectiveness examined. The guiding principle of these discussions is the notion that there exists a balance between processes involved in the maintenance of homeostasis (health) and processes resulting in damage and/or malfunction of the vital organs and other tissues of the body. The constant renewal of damaged cellular structures by protein turnover and the replacement of damaged cells by stem cell differentiation are examples of the former. The generation of oxidative stress by creation of reactive oxygen species (ROS) is an important example of the latter. Indeed, the oxidative damage theory is a pre-eminent mechanism suggested to account for the degeneration of organismic and cellular function, which underlies aging processes and ultimately limits health and life. …

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