Eating more fish—or taking fish oil pills—could protect you from colon cancer, according to a new study.

RODALE NEWS, EMMAUS, PA—A new government study finds that certain types of omega-3s found in fish can cut your risk of colon cancer by nearly 40 percent. The study, published in last month's issue of the American Journal of Epidemiology, found that DHA and EPA, found primarily in fish oil, had a greater impact on lowering colorectal cancer risk than the omega-3s found in plants or other fatty acids common in healthy foods like olive oil and other vegetable oils.

THE DETAILS: A total of 1,872 adults participated in the study, 929 of whom had already been diagnosed with some form of colorectal cancer and 943 who were healthy. Researchers interviewed all the participants about their medical histories and their physical activity levels and then asked them to fill out dietary recall questionnaires. Nutrient intake was calculated using information from the National Cancer Institute, and the researchers paid particular attention to intake of 19 different omega-6 and omega-3 fatty acids. The healthy adults had a higher intake of omega-3 fatty acids and fruits and vegetables than the adults diagnosed with cancer, and the researchers noticed among all participants that the higher the intake of omega-3s, the lower the risk of colorectal cancer. Adults who ate the most, more than 0.18 grams per day (the equivalent of one fish oil capsule) , saw as much as a 40 percent drop in risk. The benefit was greatest among people who consumed more EPA and DHA, the two omega-3s abundant in fish. The researchers didn't notice any decrease in risk when looking at ALA, the omega-3 common in flaxseeds and walnuts, or in omega-6 fatty acids, which are common in vegetable oils.

WHAT IT MEANS: Eating more fish can keep your plumbing healthy, largely because omega-3s reduce inflammation and inhibit tumor growth. And that source of omega-3s is key, as this study points out. Vegetarian sources of omega-3s, such as flaxseeds and walnuts, contain ALA, a form of omega-3 that converts to EPA and DHA in the body. But ALA doesn't convert to those other omega-3s in levels high enough to be protective, the authors write. Fish, however, contain the good omega-3s in very high levels, and the researchers saw that people gained protective effects whether they consumed fish oil from supplements or from whole fish. They even noted that fried fish provided enough healthy omega-3s—although your heart will thank you if you bake or broil your fish instead of fry it.