Studies show that some cancers are related to diet and might be prevented simply by changing what and how we eat. These changes include the types of food in our diet, how they're prepared and the overall amount of food consumed.

Foods that are believed to play a role in increasing cancer risk include:

• Foods that are exposed to high temperatures, such as charcoal-broiled foods containing high levels of fat, carbohydrates or proteins. In laboratory experiments, barbecued meats and other foods have been shown to produce mutagens that can result in tumors.
• Cured meats containing carcinogenic compounds such as nitrosamines also may be cancer producing.
• Pesticide and herbicide residue on foods have also been implicated, along with chemical preservatives, but as with all of the above factors, there is limited evidence that at the levels typically consumed they will cause human cancer.
• Obesity, which is closely related to intake of dietary fat and high calorie consumption, also is reported to be associated with tumor production. In laboratory experiments, it is clear that calorie restriction is associated with a reduction in tumors.
• Alcohol can promote several types of cancer by direct contact, including cancers of the oral cavity and larynx, and indirectly by affecting the liver and breast.

A diet rich in fruits, vegetables and whole (unprocessed) grains is believed to help reduce the risk of tumor development. These foods are rich in complex carbohydrates and fiber, factors that have been associated with a reduced risk of several types of cancer. They also contain substances that may inhibit tumor formation.