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Role of Dietary Fiber in a Cancer-Preventing Diet

Alice Bender, MS, RD, a nutritionist for the American Institute for Cancer Research, says the evidence on fiber and colon cancer, while mixed, is strong enough to make recommendations. “Our 2007 expert report looked at all the studies and concluded that foods high in fiber, not necessarily the fiber itself, can lower risk for colorectal cancer,” she tells WebMD.

“We know that a plant-based diet rich in fruits, nonstarchy vegetables, legumes, and whole grains is associated with a lower risk of a number of the most common cancers – colorectal, stomach, mouth, pharynx, larynx, and esophageal” Bender says.

Experts point out that there is not a single food, nutrient, fiber, or compound that provides the best cancer protection, however. It appears that the synergy of different foods working together is the most effective. 

“Eating a plant-based diet rich in phytochemicals, antioxidants, fiber, and other healthful plant compounds is the best way to prevent cancer -- along with regular physical activity, not smoking, and being at a healthy body weight” says Colleen Doyle, MS, RD, director of nutrition and physical activity for the American Cancer Society.

Bender and Doyle suggest these guidelines:

  • Eat a mostly plant-based diet.
  • Use the new American plate mode: Fill two-thirds of your plate with plants foods such as fruits, vegetables, whole grains, legumes, and nuts, and one-third with lean or low-fat animal products.
  • Limit red meat to 18 ounces per week.
  • Avoid processed meats.

An added plus: Plant-based foods are low in calories, which can help with weight control. Cancer experts say losing weight and getting your body mass index (BMI) into the healthy range may be more beneficial than fiber in reducing the risk of all cancers. Excess body fat is a contributor for a number of cancers, Bender says.

Make no mistake about it: Fiber is essential to your health. But if you want to reduce your risk of cancer, focus on the protective effects of whole foods such as fruits, vegetables, and grains. They contain a wealth of micronutrients and phytochemicals that work together to prevent disease.

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