Vegetarian diet may cut cancer risk

Last Updated: 2004-02-16 12:17:20 -0400 (Reuters Health)

By Alison McCook

NEW YORK (Reuters Health) - Eating a meat-free, vegetarian diet may reduce the risk of colorectal cancer, new research suggests.

After following more than 10,000 people for 17 years, investigators found that vegetarians were 15 percent less likely to develop colorectal cancer than meat-eaters.

This study adds to the "increasing scientific evidence" that a diet rich in fruit, vegetables and fiber and low in meat--especially red and processed meat--can prevent colorectal cancer, study author Dr. Miguel Sanjoaquin of the University of Oxford, UK, told Reuters Health.

However, Sanjoaquin cautioned that only a small number of study participants -95--developed colorectal cancer, making it impossible to determine if fewer vegetarians developed cancer simply due to chance.

However, Sanjoaquin noted that a previous study featuring more cases of colorectal cancer confirmed these findings, and he added that it makes sense that eating vegetarian could cut cancer risk. The fat in red meat increases the excretion of substances called bile acids, he explained, which in turn produce other substances that encourage tumor growth.

Furthermore, meat contains natural compounds and substances formed during processing and high-temperature cooking that can disrupt the normal balance of cell growth in the colon, potentially triggering the cancer, Sanjoaquin noted.

Alternatively, substances in fruits and vegetables-- staples of the vegetarian diet--"may inhibit these adverse effects," he added.

During the current study, Sanjoaquin and his colleagues asked 10,998 adults about their eating habits and other health parameters, then noted who developed colorectal cancer.

People were classified as non-vegetarians if they ate meat or fish. Vegetarians included vegans, who avoid all dairy and meat products.

Along with a decreased risk of cancer from eating vegetarian, the investigators found that frequent fruit eaters - consuming more than 5 servings of fruit per week--were over 40 percent less likely to develop colorectal cancer.

Smoking, drinking alcohol and eating more than 15 slices of white bread per week appeared to increase the risk of colorectal cancer, according to the British Journal of Cancer report.

Sanjoaquin said the fact that white bread appeared to reduce cancer risk was "unexpected," and suggested that people who ate large amounts of white bread might have simply had a less healthy diet overall.

Alternatively, he added researchers have noted that eating large quantities of refined carbohydrates, such as those found in white bread, may raise colorectal cancer risk, suggesting that white bread itself may also play a role.

"More research will be needed to clarify this," Sanjoaquin said.

SOURCE: British Journal of Cancer, January 12, 2004.


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