Good Health Habits Tied to Lower Cancer Risk

Source: Tufts University
November 14, 2002 (Reviewed: November 13, 2004)

Since 1980, the United States Department of Agriculture has issued guidelines for making food choices to promote health, prevent disease, and to serve as an outline for government food and nutrition policy and programs. While scientific knowledge is the basis for the guidelines, there is limited evidence as to whether or not adherence to the guidelines actually reduces disease incidence. A new study in the American Journal of Clinical Nutrition evaluates how effective the Dietary Guidelines for Americans are in helping to prevent cancer.

Researchers from the University of Minnesota analyzed data from the Iowa Women's Health Study (IWHS); dietary intake, lifestyle, and medical history information was collected on 34,708 postmenopausal women. The women were then given a score that reflected how closely their weight, exercise habits, and food choices complied with the Dietary Guidelines. The researchers followed the participants for 13 years to see if they developed cancer.

Cancer risk reduction

Women who scored in the highest 20% - i.e. followed the Guidelines the most closely - were 15% less likely to get cancer (of any type) than those who scored in the lowest (relative risk 0.85, 95% CI: 0.77-0.93, p for trend <0.01). This was after controlling for other factors such as age, smoking status, and hormone replacement therapy, all of which could contribute to cancer risk.

There were some statistically significant trends for specific types of cancer. As compared with those in the lowest score quintile, women in the highest quintile were at less risk of colon cancer, bronchus and lung cancers, breast cancer, and uterine cancer (all with p for trend <0.01).

Two key guidelines

To see whether the cancer protection was a result of two recommendations in the guidelines that do not focus on food - 'aim for a healthy weight' and 'be physically active every day' - the researchers removed these variables from the analysis. After doing so, the decrease in cancer risk was attenuated. In other words, much of the apparent benefit of following the Guidelines to prevent cancer was due to being at a healthy weight and exercising every day.

The American Cancer Society estimates that one-third of cancer-related deaths are related to nutrition and physical activity factors, including obesity. As the results of this study show, consumers could cut their risk of cancer quite considerably by following the Guidelines, particularly the ones pertaining to weight control and exercise. The American Cancer Society adds to these recommendations, suggesting that consumers also limit their intake of red meat, especially high fat cuts and processed meats.

Advice to patients

The Guidelines were developed to help prevent an array of chronic diseases, so some recommendations may not pertain to cancer. The US Department of Agriculture and the US Department of Health and Human Services update the Dietary Guidelines for Americans every five years. Here's a summary of the most recent recommendations:

• Aim for a healthy weight
• Be physically active every day
• Follow the Food Guide Pyramid
• Eat a variety of grains each day, especially whole grains
• Keep food safe
• Keep your intake of saturated fat and cholesterol low and moderate your intake of fat
• Eat only a moderate amount of sugar
• Use less salt
• If you drink, drink in moderation

Source

• An evaluation of the Dietary Guidelines for Americans in relation to cancer occurrence. L. Harnack, K. Nicodemus, DR. Jacobs,  et al., Am J Clin Nutr, 2002, vol. 76, pp. 889--896

Related Links
Nutrition and Your Health: Dietary Guidelines for Americans
Coaching Your Patients to Exercise
Excess Weight Adds Health Problems
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