If eaten at all, red meat should be limited to less than 3 ounces daily. It is preferable to choose fish or poultry.

These latest findings -- from the largest scientific study ever to investigate the links between diet and cancer risk -- corroborate what cancer experts at the American Institute for Cancer Research (AICR) have been saying for years, the organization noted. AICR recommends limiting consumption of red meat to no more than 3 ounces per day.

Researchers tracked the diets of over half a million subjects in ten European countries for an average of 5 years. They found that those subjects who ate the most red meat (beef, pork, veal, lamb) and processed meats (sausages, ham, bacon, and cold cuts) had a 35 percent greater risk of developing colon cancer compared to those subjects who ate the least of these foods.

Fish Consumption Lowers Risk

The same study also revealed that consumption of fish was associated with lower risk of colon cancer. Previous evidence linking consumption of fish to lower risk colon cancer has been less consistent.

Subjects who ate the most fish (including fresh, canned, salted and smoked fish) had a 31 percent lower risk of developing colon cancer than subjects who ate the least.

The authors found that the two effects -- meat increasing risk and fish lowering risk -- were independent of each other. This is intriguing, says AICR, because many experts have assumed that any lowering of colon cancer risk seen in populations who consume diets high in fish should be attributed to the relative lack of meat in such diets.

The new study is the strongest evidence yet that consumption of fish has a measurable and significant protective effect against colon cancer, notes AICR. Although the authors did not distinguish between types of fish, the existence of such a protective effect seems to align with recent laboratory and clinical evidence on the anti-cancer activity of omega-3 fatty acids, found in tuna, salmon and other cold water "fatty fish," the organization notes.

Poultry Has No Effect

Among the study subjects, consumption of poultry (chicken and turkey) had no effect on colon cancer risk.

All of this new evidence will be factored into a report authored by AICR and the World Cancer Research Fund that will assess and evaluate thousands of studies on diet and cancer risk, according to AICR. It will be published in the fall of 2007.

Until that time, AICR's advice for individuals looking to lower their risk for cancer remains unchanged: If eaten at all, red meat should be limited to less than 3 ounces daily. It is preferable to choose fish or poultry.