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Fiber: High or Low?

salad filled with tomatoes, corn, carrots and spinach

by Nancy Burke, R.D., Danielle Karsies, M.S., R.D. and Melissa Shannon-Hagen, R.D., C.S.O., University of Michigan Rogel Cancer Center Symptom Management and Supportive Care Program

Cancer and treatment can change your dietary needs

We often hear that fiber is great for our health. It's true that fiber in our diets acts as a wonderful scouring brush that cleans our gastrointestinal tract, keeping it healthy and reducing the risk of diverticulitis and colorectal cancer.

Evidence also shows that fiber lowers cholesterol levels, controls blood glucose levels and promotes heart health and weight management.

But, for cancer patients, there are instances when fiber-rich foods may actually aggravate your stomach. At these times, a modified fiber diet can help.



Abdominal radiation and chemotherapy can cause diarrhea, which means the beneficial scouring action of fiber rubs your already inflamed GI tract. Focus on limiting insoluble fiber or roughage (such as whole grains, legumes) while still allowing some soluble fiber (such as bananas, oats) in small amounts.

Chemotherapy and some medications for pain related to cancer treatment and surgery increase your risk of constipation. Signs to watch for include not having a bowel movement at least every three days, bowel movements that require significant effort or the feeling that it's not complete after you have one.

Constipation can be caused by:

  • Decreased movement of your GI tract
  • Impacted reflexes involved with having a bowel movement
  • Reduced intestinal secretions
Adding more fiber to a backup of stool within your GI tract is not always helpful. Think of it as a traffic jam; if you add more cars to the backup you add to the jam.

Chemotherapy and abdominal radiation can cause nausea, and these treatments can make digestion less efficient. Asking your stomach to break down high-fiber foods can make your nausea worse.



Modified Fiber Diet

  • Peel fresh fruits and vegetables before eating
  • Use canned fruits and vegetables in place of fresh
  • Use oat bread or white bread in place of 100 percent whole wheat/grain or varieties with seeds or nuts
  • Choose nut and seed butters (such as peanut or sunflower butter) over whole nuts or seeds
  • Eat cooked vegetables over raw vegetables

Move More

  • Physical activity regularly encourages the GI tract to work better
  • Drink 64-80 ounces of fluids daily (water, juice, tea, soup)
  • Eat frequent small meals to encourage GI movement more often. This also means your GI tract doesn't have to work as hard at one time.

If you're a U-M Rogel Cancer Center patient, call our dietitians for nutritional counseling and dietary solutions for your symptoms and side effects at 1-877-907-0859.

Read the Fall, 2016 issue of THRIVE.

Learning more about nutrition and cancer treatment-related side effects

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Thrive Issue: 
Fall, 2016