Dietary Fiber for Prostate Cancer

General Information

Dietary fiber is derived from the structural components of plants. It includes the storage and cell wall parts of plants that cannot be broken down by human digestive enzymes. Fiber absorbs 10 to 15 times its weight in water. Therefore, it brings fluids to the intestines and increases movement of the bowels. Dietary fiber has many functions in the body. It may bind to carcinogens and other harmful compounds and eliminate them from the body.

Dietary fiber can be soluble or insoluble. Soluble fiber can be digested, and insoluble fiber cannot be digested. Sources of insoluble fiber include some fruits, fresh and cooked vegetables, wheat bran and whole grains. Sources of soluble fiber include apples, citrus fruits, oat bran, barley and legumes. In addition, fiber can lower cholesterol levels and decrease risks for some cancers. Fiber has also demonstrated the ability to lower the risk of prostate cancer progression. In fact, fiber may have the ability to decrease levels of testosterone. By eating high levels of soluble fiber, men may be able to lower their plasma levels of testosterone. Therefore, the testosterone is not available to stimulate tumor growth.

Medical Research/Studies

In a study by Tariq and associates, healthy men were given diets high in soluble or insoluble fiber. Prostate-specific antigen (PSA), a serum prostate cancer marker, decreased 10% after four months in the men on the diet high in soluble fiber. The levels of plasma testosterone also declined in the men on the high insoluble-fiber diet. These lower levels of testosterone were due to increased excretion of testosterone in the feces. Researchers are confident that these decreased levels of testosterone may be an effective way to prevent the progression of primary prostate cancer.

Urology Center Recommendations

  • Increase your fiber intake to 25 - 35 grams per day.
  • Good sources of fiber include whole fresh fruits and vegetables, whole grain breads and cereals and beans.
  • Fiber should come from a wide variety of natural foods. Avoid supplements.
  • Your dietary fiber intake should consist of both soluble fiber and insoluble fiber.
  • A good source of fiber should have at least three grams of fiber per serving.
  • High-fiber foods provide five grams or more of fiber per serving.
  • Increase your dietary fiber intake slowly to avoid gas and/or diarrhea.

Sources of Dietary Fiber


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