Answer to Question 1
The most common type of arthritis that disables older people is osteoarthritis, a painful swelling of the joints. During movement, the ends of bones are normally protected from wear by cartilage and by small sacs of fluid that lubricate the joint. With age, the cartilage sometimes disintegrates, and the joints become malformed and painful to move.
Obesity is common among adults with arthritis. Weight loss can help overweight people with osteoarthritis, partly because the joints affected are often weight-bearing joints that are stressed and irritated by having to carry excess pounds. Interestingly, though, weight loss often relieves the worst pain of osteoarthritis in the hands as well, even though they are not weight-bearing joints. Jogging and other weight-bearing activities do not worsen osteoarthritis. In fact, both aerobic activity and weight training offer modest improvements in physical performance and pain relief, especially when accompanied by even modest weight loss.
Two popular supplements for treating osteoarthritisgluco samine and chondroitinmay alleviate pain and improve mobility, but mixed reports from studies emphasize the need for additional research. Drugs and supplements used to relieve arthritis can impose nutrition risks; some affect appetite and alter the body's use of nutrients.
Another type of arthritis, known as rheumatoid arthritis, has a possible link to diet through the immune system. In rheumatoid arthritis, the immune system mistakenly attacks the bone coverings as if they were made of foreign tissue. In some individuals, certain foods, notably a Mediterranean-type diet of fish, vegetables, and olive oil, may moderate the inflammatory responses and provide some relief. The omega-3 fatty acids commonly found in fish oil reduce joint tenderness and improve mobility in some people with rheumatoid arthritis. The same diet recommended for heart healthone low in saturated fat from meats and milk products and high in omega-3 fats from fishhelps prevent or reduce the inflammation in the joints that makes arthritis so painful.
Answer to Question 2
In their efforts to understand longevity, researchers have not only observed people but have also manipulated influencing factors, such as diet, in animals. This research has produced some interesting and suggestive findings. For example, animals live longer and have fewer age-related diseases when their energy intakes are restricted. These life-prolonging benefits become evident when the diet provides enough food to prevent malnutrition and an energy intake of about 70 percent of normal; benefits decline as the age at which energy restriction begins is delayed.
Exactly how energy restriction prolongs life remains unexplained, although gene activity appears to play a key role. Energy restriction in animals prevents alterations in gene expression that are associated with aging. Food restriction may also extend the life span by preventing damaging lipid oxidation, thereby delaying the onset of age-related diseases such as cancer and atherosclerosis. Other research suggests that energy restriction beneficially alters several aspects of fat cell metabolism, which may play a role in reducing chronic disease risk and extending life. Experiments with food restriction and longevity in animals have not suggested any direct applications to human nutrition.
Moderate energy restriction (80 to 90 percent of usual intake) in human beings may be valuable. When people restrict energy intake moderately, body weight, body fat, and blood pressure drop, and blood lipids and insulin response improvefavorable changes for preventing chronic diseases. The reduction in oxidative damage that occurs with energy restriction in animals also occurs in people whose diets include antioxidant nutrients and phytochemicals. Diets such as the Mediterranean diet that include an abundance of fruits, vegetables, olive oil, whole grains, and legumeswith their array of antioxidants and phytochemicalssuppo rt good health and long life.
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