This method has been shown to give rise to certain biases. This study was actually an analysis of eight previous studies that, like the Michels study above, tracked the reported diets of subjects using a questionnaire for several years. Once again, the authors found that those subjects who said they ate the most vegetables and fruits had no fewer cases of breast cancer than other subjects. Moreover, several of the previous studies that the authors analyzed neglected to collect data on apples, bananas, peaches, apricots, broccoli, brussels sprouts, cabbage, lettuce, spinach, string beans and tomatoes. In light of these important limitations, the letter signed by 54 cancer researchers from across the country concludes by placing the studies in a larger context.
Scientific investigation is an ongoing process.
More studies on diet and cancer will be reported to the public. When it comes to something as important as personal health, the public should always look to the preponderance of scientific evidence, not simply the latest study. Evidence that has been building for decades swings heavily in favor of a long-term diet high in vegetables and fruits for reducing risk for cancer, as well as heart disease, diabetes and obesity. An independent cancer research organization, the Institute receives no significant funding from any corporation that produces, markets or distributes vegetables and fruits. The Institute provides a wide range of consumer education programs that help millions of Americans learn to make dietary changes for lower cancer risk.