Behavioral Factors and Aging
Behavioral Factors and Aging
Salads in fast-food restaurants and low-fat labels in supermarkets signal a transformation in Americans' eating habits that is reflected in mortality rates. Deaths from heart disease have declined 45 percent in the United States since 1950, partly due to the switch to lower-fat, lower-cholesterol diets, and to other behavioral factors, like smoking cessation and exercise.
Diet and exercise, in particular, are thought to have a major impact on a constellation of changes that are common with advancing age. These include higher levels of fats or lipids in the blood, changing levels of blood sugar and insulin, a tendency toward obesity, and increased central body fat -- that which settles around the waist and abdomen. So common are these among older people that they have been given a name -- syndrome x -- and their relationship to heart and other cardiovascular diseases is the focus of many studies.
Syndrome x may be preventable through low-fat and low-cholesterol diets, but these are not the only aspects of nutrition that may influence life expectancy. Gerontologists have been scrutinizing a wide range of nutrients with an eye toward their role in aging processes. Calcium and vitamin D, for example, help reduce the thinning of bones that accompanies aging in almost everyone but particularly in older women, many of whom are at high risk for osteoporosis. Another nutrient, vitamin E, may be critical to the immune system, while beta carotene, vitamin C, and vitamin E appear to fight oxidative damage.
Startling to many experts is the finding that most older people are not getting the recommended daily allowances (RDA's) of some nutrients. The Baltimore Longitudinal Study on Aging found deficiencies among elderly people in calcium, zinc, iron, magnesium, vitamins B6, B12, D, and E, and folic acid, a finding confirmed at the USDA Human Nutrition Research Center on Aging. Nutritionists point out that precisely what the RDAs should be for older people is not clear.
Researchers are also studying exercise as a behavioral factor that may have an impact on how long we live -- or at least on how healthy we are in old age. One landmark study at Tufts has shown that exercise can strengthen muscles, improve mobility, and reduce frailty even among 90-year-olds.
Exercise at 90: It Works.
Exercise is a powerful health promoter at any time of life. Even 80- and 90-year-olds can benefit, according to a study by Maria Fiatarone of the USDA Human Nutrition Center on Aging at Tufts University. Here is how Fiatarone described her findings to the House Select Committee on Aging in February 1991:
"Starting with a small group of ten 90-year-old residents of the Hebrew Rehabilitation Center for Aged in Massachusetts, we demonstrated that the muscle weakness and atrophy of aging were in fact not at all immutable. These residents increased their leg muscle strength by 174 percent and their muscle size by 9 percent after only 8 weeks of weight-lifting exercise. More importantly, as we have expanded this research to a much larger group of volunteers through the support of grants from the National Institute on Aging and others, it is clear that such training can improve walking speeds, mobility, independence in daily activities, and reduce dependence on canes, walkers, and wheelchairs in some individuals. At a cellular level, we now have preliminary evidence that this increased muscle function is accompanied by the actual growth of new muscle fibers, a finding never before demonstrated after strength training."
Rose Karsh, a participant in the study, described it from her point of view: "When I finished the study I was able to life 50 pounds with each leg which surprised me very much at my age. After the test was over I was able to walk around the center without any assistance, and it made me feel very proud that I could do that. It made me feel younger and gayer. I use my cane to protect myself from falling only when I walk outside. I don't have to use a walker."
Exercises that put weight on bones, such as jogging, walking, and weight-lifting, have been shown to strengthen them. Researchers, as a result, are exploring the potential of exercise to reduce the risk of osteoporosis. This condition, with its fragile, easily broken bones, is a major cause of fractures among older people, frequently results in disability, and eventually leads to institutionalization for many.
See also: Hormones and Aging