& Joannie Dobbs Monday,
Exercise helps prevent and treat cancers
When it comes to the health benefits of exercise, people naturally think of how it reduces the risk of heart disease. But a physically active lifestyle also reduces the risk of various cancers.
Question: What types of cancer does exercise affect?
Answer: A lifestyle that includes frequent and consistent physical activity helps protect against colon, breast, prostate and lung cancers. The evidence is strongest for colon cancer. A physically active lifestyle reduces that risk by as much as 50 percent. Exercise also could help prevent other cancers, but more research is needed.
Q: How does exercise help?
A: People who are moderately active on a regular basis generally have better overall function of their immune systems. Both sedentary individuals and extremely active people who overextend themselves can have compromised immune systems. In addition, some researchers believe exercise has an effect on the colon somewhat like that of dietary fiber -- helping to keep fecal matter on the move. It is also thought that exercise can help alter the concentration of hormones related to an increased risk for breast and prostate cancers.
Q: How much exercise is necessary?
A: Recommendations for cancer prevention are based on establishing lifelong exercise habits. A report last year from an American Cancer Society committee recommended that children and adolescents "engage in at least 60 minutes per day of moderate to vigorous physical activity at least five days per week." For adults the suggestion is moderate activity for at least 30 minutes, five days per week -- "45 minutes or more of moderate to vigorous activity on five or more days per week may further enhance reductions in the risk for breast and colon cancer."
If you have been a couch potato for years, consult qualified health and fitness professionals on how to gradually get back into the swing of staying active. Don't try to go straight from the couch to vigorous activity. Getting into shape is a gradual process.
Q: Can exercise benefit those who are receiving treatment or recovering from cancer?
A: Certainly. Many cancer treatments reduce the capacity to exercise, but there is evidence that maintaining a reasonable level of activity during treatment can enhance quality of life and could even improve the survival rate for some cancers, such as colon cancer.
The American Cancer Society report found that physical activity after cancer treatment might be even more important. It appears to enhance overall survival and might reduce recurrence of breast and colon cancers in particular.
Other healthy habits support the benefits of exercise. These include a balanced diet with plenty of vegetables, fruits and whole grains, and modest amounts of lean proteins and lower-fat milk products; maintaining healthy weight; and limiting alcohol consumption.
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S.
are nutritionists in the Department of Human Nutrition, Food and Animal Sciences,
College of Tropical Agriculture and Human Resources, UH-Manoa.
Dr. Dobbs also works with the University Health Service
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