Both the meat-laden “Western” diet and the traditional, salty diet of the Japanese apparently increase the risk of Colon cancer - at least for women, new research shows.

Researchers in Japan found that among more than 42,000 adults followed for 10 years, women (but not men) with either a Western pattern of eating or a diet heavy in traditional Japanese foods like salted fish and pickled vegetables had a higher risk of Colon cancer compared with women who were deemed healthy eaters.

For their study, the investigators defined three different dietary patterns based on survey respondents’ reported eating habits. One was dubbed the Western dietary pattern, and was marked by high intakes of meat, poultry, cheese and bread and butter.

A second category, the “traditional” dietary pattern, was built around rice, miso soup, salted fish and pickled vegetables.

The third dietary pattern was the “healthy” one, and it included high amounts of fruits, vegetables, soy products, beans and dairy.

Overall, women whose diets were the most Western had more than double the risk of developing colon cancer as women with the least Westernized diets. Similarly, women who ate the most traditional foods were twice as likely as those who ate the fewest to be diagnosed with colon cancer.

The healthy eating pattern was not linked to colon cancer risk at all.

Dr. Mi Kyung Kim and colleagues at the National Cancer Center in Tokyo report the findings in the July 10th issue of the International Journal of Cancer.

A number of studies have suggested that diets high in animal products and saturated fat may raise the risk of Colon cancer. A large European study published last week found that people who regularly ate hefty servings of red or processed meat had an elevated risk of the disease, as did people who got little fiber in their diets.

In that study, fish consumption in general was tied to a lower risk of colon cancer.

In addition, heavy consumption of salted fish and vegetables, staples of the traditional Japanese diet in the current study, has been tied to higher colon cancer risk. The reasons are unclear, but research in lab animals has shown that substances in salt-preserved foods called nitrosamines may promote cancerous changes in cells, Kim’s team points out.

Though the current study did not find a protective effect of the “healthy” eating pattern, study co-author Dr. Shoichiro Tsugane said, it’s still “wise” for people to replace some meat and processed foods with fruits, vegetables and whole grains.

The American Cancer Society recommends that people exercise regularly and follow a diet rich in fruits, vegetables and whole grains as one way to lower the risk of colon cancer.

Why the various diets in the current study were linked to Colon cancer only among women is uncertain. It’s possible, Tsugane said, that smoking and habitual drinking - two factors associated with colon cancer - may have “masked” any effect of diet on men’s risk of the disease.

Many Japanese men, Tsugane said, smoke and drink alcohol, while the habits are much less common among women.

SOURCE: International Journal of Cancer, July 10, 2005.