Can a High-Fiber Diet Cause Rectal Bleeding?

Fiber prevents constipation and diarrhea.
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A high-fiber diet is healthy, with the Colorado State University Extension recommending that adults eat at least 14 g of fiber per day for every 1,000 calories in their diet. High amounts of dietary fiber do not cause rectal bleeding, but a fiber-rich diet prevents certain conditions that cause this problem. Rectal bleeding sometimes signals a serious condition like cancer, but less-dangerous causes are often alleviated by eating enough fiber.



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Rectal bleeding is often caused by diverticular disease, a condition that is usually triggered by a low-fiber diet, according to the National Digestive Diseases Information Clearinghouse. Diverticulosis, a form of this disease, causes bright, red blood to pass out of your body from the colon and rectum. Ulcers may also cause rectal bleeding, but the blood is darker because it comes from higher up in the digestive system. Hard stool or a bad case of diarrhea may tear tissue lining the anus, resulting in a bleeding fissure. Hemorrhoids, which are dilated rectal blood vessels, may also bleed, although this is less common.

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Fiber Effects

Fiber helps prevent rectal bleeding from diverticulosis, fissures and hemorrhoids because it prevents or improves those conditions. The National Digestive Diseases Information Clearinghouse advises that inadequate dietary fiber is the main cause of this intestinal problem. Fiber prevents it by absorbing water, which makes stool bulkier and easier to pass out of the body. The water absorption also prevents diarrhea. Easier bowel movements mean less chance of fissures and hemorrhoids.



All dietary fiber comes from plant-based sources, and there are two different types, both of which prevent rectal bleeding. Insoluble fibers moves through your intestines almost intact, bulking up your feces to help you have regular, easy bowel movements. Soluble fiber turns gelatinous when exposed to water, so it aids digestion and also helps bring down your cholesterol and glucose levels.



Add fiber to your diet by eating large amounts of fruits, vegetables, legumes and products made with whole grains. You can ensure a healthy level of fiber by taking a supplement if you do not reach the recommended daily levels through diet alone.


Rectal bleeding can be a sign of a serious illness like colon cancer. Benign polyps may also bleed and need treatment because they can turn cancerous, the Nebraska Colon Cancer Screening Program advises. Contact your physician immediately if you have rectal bleeding along with stomach pain, constipation, thin stool, ongoing weight loss, high fever, vomiting, nausea, severe diarrhea or uncontrolled stool seepage, as these symptoms could come from a condition that needs immediate attention.




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