Nov. 15, 2002 -- A new study serves as good evidence that a western diet can more than double the risk of colon cancer. Researchers found that an increasingly western diet has led to a dramatic rise in colorectal cancer in Singapore. Rates of the cancer have doubled in the past three decades, largely because residents eat more red meat and fewer vegetables than in the past.
Singapore is one of Asia's most rapidly developing nations. And for many of the ethnic Chinese who make up 77% of the population, industrialization has brought both changes in diet and a more sedentary lifestyle. Colorectal cancer rates now approach those in developed countries and are among the highest in Asia.
To determine the influence of changing lifestyles on cancer rates, researchers from the National University of Singapore conducted interviews with 121 Chinese colorectal cancer patients and 222 healthy Chinese people. The findings appear in the Dec. 1 issue of the journal Cancer.
Researchers concluded that diet and a family history of colorectal cancer were the primary risk factors for the disease in the Chinese population. After accounting for all other risk factors, a high intake of red meat -- including beef and pork -- doubled the risk of colorectal cancer. No rise was seen for those reporting increased consumption of other meats or seafood. Eating vegetables was associated with a reduction in risk.
People who ate lots of red meat and few vegetables were more than 2.5 times more likely to get colon cancer. Eating lots of vegetables reduced the risk only slightly in those who also ate large amounts of red meat, but the risk was still almost double that of the healthy population. No other food groups -- including soy, legumes or fruit -- were found to have an impact on risk.
"Dietary intake of red meat in Western populations has been related to the risk of colorectal [cancer] in many, but not all, studies, and this appears to be independent of its contribution to total fat or protein content," lead researcher Adeline Seow, MD, and colleagues noted.
The National Cancer Institute's Arthur Schatzkin, PhD, who is an expert on the role of foods in cancer, tells WebMD that the evidence linking red meat consumption to colorectal cancer is strong but not conclusive. The consumption of processed meats has also been linked to colorectal cancer. Schatzkin is chief of the Nutritional Epidemiology Branch of the NCI's Division of Cancer Epidemiology and Genetics.
"The majority of studies support the red meat link, but we have seen several widely accepted hypotheses become controversial," he says. "Until recently the link between dietary fiber and a reduced risk was accepted. Several well publicized studies challenged that idea, but they did not totally refute the hypothesis."
Colorectal cancer expert Charles Fuchs, of Boston's Dana Farber Cancer Institute, says that evidence suggests that eating red meat in moderation is safe. But how much is too much? Fuchs cites findings from a large U.S. study, which showed that women who ate beef, pork, or lamb five or more times a week had triple the risk of colon cancer.
"There are a lot of good reasons to be moderate in one's consumption of red meat, not the least of which is its link to heart disease," he tells WebMD. "Eating red meat more than five times a week is probably too much."