Colorectal cancer survivors may be able to reduce their risk of death by eating more fiber and whole grains, according to a new study from researchers at Massachusetts General Hospital and Harvard Medical School.

By the numbers: The study analyzed data from two studies of doctors and nurses that tracked food intake with regular questionnaires over multiple decades. Out of 1,575 patients diagnosed with stage 1 to 3 colorectal cancer, 773 had died from various causes, including 174 who died from colorectal cancer.

When researchers compared fiber intake to death rates, they found every 5 gram increase in daily fiber intake reduced the chance of death from colorectal cancer by 18 percent, and the chance of death from any cause by 14 percent. The maximum benefit was achieved at 24 grams per day of fiber. Cereal fibers had the largest impact on death rates, while vegetable fiber intake lowered overall death rates, but not from colorectal cancer. Fruit fiber intake had no impact on death rates.

Bottom line: Researchers were not able to randomly assign the patients to high or low fiber diets, so no firm conclusion could be drawn about a protective effect. The study findings are supported by previous research that every 10-gram increase in fiber intake lowered the risk of colorectal cancer by 10 percent. But the question of whether fiber could prevent colorectal cancer recurrence had not been previously tested.