Numerous observational and cohort studies have assessed and found inconclusive the relationship of a low-fat, high-fruit, and high-vegetable dietary pattern with breast and colon cancer risk. Principal results of the randomized controlled Women's Health Initiative Dietary Modification TrialArticleArticleArticle, which directly assessed the health benefits of a low-fat eating pattern, are reported in this issue of JAMA. Postmenopausal women in the intervention group were advised to reduce total fat intake to 20% of energy and to consume at least 5 servings of fruits and vegetables and 6 servings of grains daily; women in the control group continued their usual eating pattern. For an average of 8.1 years of follow-up, the investigators found the dietary intervention was associated with a modest but statistically nonsignificant reduction in invasive breast cancer and no reductions in the risks of colorectal cancer, cardiovascular disease, coronary heart disease, or stroke. In editorials, BuzdarArticle discusses the role of dietary intake in breast cancer risk and relapse prevention, and Anderson and AppelArticle discuss the implications of these results for future dietary interventions to reduce cardiovascular disease.