Coffee and sodas not tied to colon cancer

NEW YORK (Reuters Health) - You can keep on chugging coffee without worrying about whether your java will increase your risk of colon cancer, according to new research.

The same appears true for soda, while in the study tea was tied to a small increase in risk of the common cancer. However, that finding could have been due to chance, the researchers say.

Colon cancer rates vary as much as 25-fold between countries, and scientists believe lifestyle differences could be involved. Coffee and tea, for example, contain a mixture of substances that may prevent or promote cancer. The question has been, which ones get the last word?

"Cutting down or removing sugar-sweetened beverages from the diet was viewed as a major target for preventing major cancers," noted Dr. Barry Popkin of the University of North Carolina, who was not involved in the study.

Pooling data from several earlier studies, Harvard researchers followed some 700,000 people for up to 20 years after they had reported their dietary habits.

Fewer than one in a hundred developed colon cancer, and neither coffee nor soft drinks influenced that rate appreciably.

"Drinking coffee, even more than six cups a day, was not associated with risk of colon cancer," said Dr. Xuehong Zhang of the Harvard School of Public Health, who worked on the study. The findings, published in the Journal of the National Cancer Institute, square with earlier research for coffee.

Soft drinks have been tied to increases in risk factors for colon cancer, such as obesity and diabetes, but there had been little direct research of the subject. The new findings should be interpreted with caution, Zhang said, because very few people drank high amounts of soft drinks, or more than 18 ounces per day.

Another limitation is that adults usually drink fewer soft drinks than children. "Intake of sweetened beverages may need to be assessed earlier in life," Cynthia A. Thomson and Maria Elena Martinez, of the University of Arizona, noted in an editorial accompanying the findings.

For the heaviest tea drinkers, who drank at least four cups a day, the risk of developing colon cancer rose by 28 percent, on average. However, that link could be due to chance, or factors that the researchers didn't measure --whether or not people put sugar and milk in their tea, or had pastries with it, for example.

"The relationship between tea and colon cancer is unclear for the time being," said Zhang.

SOURCE: Journal of the National Cancer Institute, online May 7, 2010.