Fiber & colon cancer … again

Nutrition Action Healthletter, July-August, 2003

Can a high-fiber diet cut the risk of colon cancer? After several disappointing studies, two new reports suggest that fiber may indeed be protective.

In one, which looked at nearly 38,000 people, those who consumed the most fiber (more than 30 grams a day) were 27 per cent less likely to have colon polyps than those who ate the least fiber (less than 15 grams a day).

In the second, researchers asked more than 500,000 people from ten European countries to complete diet questionnaires between 1992 and 1998. Those who reported the highest fiber intakes (at least 32 grams a day) had a 42 percent lower risk of being diagnosed with colon cancer by 2002 than those who consumed the least fiber (less than 13 grams a day).

What to do: It's not clear why fiber appeared to protect the colon in these studies, but not in earlier (equally good) research. It's possible that people didn't eat enough fiber for enough time in some of the earlier studies. But it's also possible that something else about the fiber-eaters in the new studies reduced their risk.

Either way, it makes sense to eat fiber-rich foods like whole grains, beans, fruits, and vegetables. If nothing else, they should help reduce the risk of heart disease, diverticulosis, and constipation.

Lancet 361: 1491, 2003.