Since 1980, the Dietary Guidelines for Americans has provided advice for Americans about food choices that may promote health and prevent a variety of chronic diseases. The Guidelines are reviewed and updated every 5 years to reflect current nutritional research. In an article published in the American Journal of Clinical Nutrition, Harnack et al. evaluated data from the Iowa Women's Health Study regarding nutrition-related behaviors in a large group of postmenopausal women. They found that better compliance with the Dietary Guidelines resulted in an overall reduced risk for cancer, although measures of physical activity and weight status may have influenced this outcome.
The female study population were rural residents of Iowa and were 99% white. A total of 34,708 postmenopausal women completed a series of questionnaires on diet and lifestyle factors and were followed for cancer incidence and mortality. During a 13-year period, 5038 cancers were diagnosed in the group. Each woman was assigned an index score based on compliance with dietary recommendations contained in the Dietary Guidelines, as well as nondietary recommendations relating to lifestyle. The women were divided into 5 quintiles according to their index scores; for instance, those in quintile 5 tended to be more physically active, eat more whole grains and less fat, eat more fruits and vegetables, and to be non-smokers. Compared to the lowest quintile of compliance, overall cancer incidence for the 2nd lowest quintile was reduced by a non-significant 5%, by a significant 12% for quintiles 3 and 4, and by 15% for quintile 5. The decline in risk was quite dramatic for some forms of cancer: women in quintile 4 had less than half the risk of uterine cancer of those in the lowest quintile. Risk reduction for breast and colon cancer declined an average of 25% from quintile 1 to quintile 4. The reduction in cancer risk was
Contact: Elizabeth Horowitz
American Journal of Clinical Nutrition