Medical Health Encyclopedia

Of further interest, however, is a 2001 study that reported a possible link between colon cancer and trans fatty acids, which are partially hydrogenated oils found in stick margarine, fried foods and commercial baked goods. The association is supported by known chemical effects of these manufactured fats, and more research is warranted.

Monounsaturated Fats. Monounsaturated fats are mostly present in olive, canola, and peanut oils and in most nuts. Olive oil, for example, may protect the colon. Some evidence suggests that it reduces levels of deoxycholic acid, an acid found in bile that has tumor-promoting properties.

Polyunsaturated Fats. Polyunsaturated fats are found in both plant and fish oils, and are composed of essential fatty acids including omega-3 and omega-6 fatty acids. These fatty acids may play different roles in colon cancer.

• Omega-3 fatty acids are found in oily fish and canola oil, soybeans, flaxseed, and certain nuts and seeds. They have been associated with protection against inflammation in the intestinal tract. It should be noted, however, that not all studies show protection. For example, omega-3 fatty acids in fish are composed of docosahexaenoic (DHA) and eicosapentaneoic (EPA) acids. Some evidence suggests that EPA--although not DHA--may be protective.
• Omega-6 fatty acids, found in corn, safflower, soybean, and sunflower oil, constitute most of the oils consumed in the US. Some omega-6 fatty acids are important for health. However, a high intake has been associated with heart disease and certain cancers.

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Currently it is reasonable to reduce saturated fats and transfatty acids and to favor monounsaturated oils and polyunsaturated oils, particularly containing omega-3 fatty acids.

Meat and High-Temperature Cooking

Some evidence suggests that red meat raises the risk for colon cancer. Red meat contains dietary iron, which has been associated with a higher risk for colon cancer. In fact, early results in 2000 from the largest study on diet and cancer to date have supported previous studies linking red meat with intestinal tumors.