Fruits, Vegetables, and Colorectal Cancer

Studies have shown that a diet high in fruits and vegetables can help you avoid a number of types of cancers, including oral cancers, skin cancer, and prostate cancer. But the effect of a diet high in fruits or vegetables has not yet conclusively linked to the incidence of colon or rectal cancers. A team of researchers recently reported on a large-scale study specifically designed to evaluate the risks of several types of cancers, including colorectal cancer (Am J Clin Nutr 2007;86(6):1754-64).

Over 32,000 men and women between the ages of 55 and 74 answered a detailed dietary questionnaire, then were given an initial sigmoidoscopy (a screening test for colon and rectal cancer). The relative amounts fruits and vegetables the subjects consumed were grouped into five increasing levels of intake, then that intake was compared with the intake of those subjects who were diagnosed with colorectal adenoma, a precursur of colon or rectal cancer. The difference between the highest level of fruit or vegetable consumption and the lowest level was about 5 servings per day.

After controlling for such risk factors as age, gender, weight, and ethnicity, the scientists found that those subjects consuming the highest amount of fruit or vegetables were less likely to develop colorectal adenomas. The researchers then looked at all fruits and all vegetables separately, finding that the highest level of fruit intake, not including fruit juices, had a reduction in their risk of colorectal cancer of about 15% compared to the lowest level of fruit intake. Specific types of vegetables, such as deep-yellow vegetables, onions, and garlic were also shown help reduce the risk of colorectal adenomas by up to 11%.

What this means for you

Previous studies looking at fruit or vegetable intake have given mixed results. Is it the fruit? Is it the vegetables? Is it the folate in the fruits or vegetables, or is it the fiber? What is clear, however, is that eating a diet high in fruits and vegetables is good for you for a number of reasons. During the holidays it can be all too easy to overlook the fruits and vegetables altogether in favor of holiday cookies. Help keep your intake up by keeping fruits like apples and bananas on hand, so you can snack on them, or try keeping cut carrots and celery in zipper bags in the fridge. Not only will you help reduce your risk of colon cancer, but you'll also be less likely to snack on those holiday cookies or candies.

First posted: December 12, 2007