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March 8, 2018 | 4 minute read

Keeping Your Gut Healthy During and After Cancer Treatment

Updated on April 21, 2021

March is National Nutrition Month so AICR’s blog today focuses on proper dietary care for digestive concerns during cancer treatment and rehabilitation. Patients and survivors experience digestive issues during and after treatment for many types of cancer due. Here, Angela Hummel offers food and nutrition tips and advice on managing digestive side effects due to the disease and treatment.  Hummel is a specialist in oncology nutrition and is a consulting dietitian with AICR.

woman jogging with white sneakers

I interact with people undergoing cancer treatment. In the process, I have learned a lot about nutritional counseling to patients and their families/caregivers at different stages of their cancer treatment and rehabilitation. Most people experience digestive problems related to their cancer or cancer treatment. As a certified specialist in oncology nutrition, I have the opportunity to guide people on strategies to maximize nutrition impact during their period of treatment and beyond.

Caring for your digestive tract during cancer treatment

The health of the digestive tract is imperative for good nutritional status. As an oncology nutrition specialist, I help people with digestive problems, such as gas, bloating, diarrhea, and constipation, ranging from mild to severe for all different cancer types and their treatments. I find it interesting how side effects range from person to person.

Here are four common concerns people ask about:


Changes in bowel habits are common during cancer treatment and I have helped many patients deal with significant constipation. Constipation can interfere with appetite and nutritional status. Many factors related and unrelated to cancer can contribute to constipation, such as medications used to help with cancer treatment, inadequate fluid intake, changes in eating habits and a decrease in activity.

I often discuss techniques to manage constipation. Some general guidelines to improve constipation include:

• Increase fiber intake to around 25-35 grams

• Increase fluid intake to 8 cups spread throughout the day

• Raise physical activity to at least 30 minutes


I know from experience that the above strategies for managing constipation may not work or be feasible during cancer treatment. If poor appetite and fatigue during treatment are making it hard for you to eat and get that much activity try these additional strategies:

• Eat at consistent times throughout the day

• Sip a hot beverage like warmed prune juice or decaffeinated tea around the time you would normally have a bowel movement

• Increase fluids by sucking on ice chips, frozen fruit or by including soups with meals

• Take a short walk for 10-15 minutes prior to eating


Talk with your healthcare team regarding your bowel habits. Medical intervention can help relieve constipation and help you achieve better nutritional status.

Prebiotics and Probiotics

I often talk with patients about prebiotics and probiotics during treatment. Probiotics are the healthy bacteria that live in our digestive tract and prebiotics are the food required by the healthy bacteria. Pre- and probiotics can help cancer patients, particularly colorectal cancer patients, because they are more likely to suffer from the problem of gas, bloating and diarrhea.

Prebiotics include many healthy plant fibers from choices like bananas, onions, asparagus, oatmeal, beans, and legumes. Foods that naturally contain healthy, living bacteria (probiotics) are yogurt, kefir, buttermilk, kombucha tea, sauerkraut, kimichi, and tempeh.

Choosing prebiotic and probiotic foods daily during and after cancer treatment can promote a healthy digestive tract. Many probiotic supplements are available over-the-counter. However, during cancer treatment, if you are considering using these products, it is important to talk with your healthcare team first due to the risk of immune suppression from some treatments and potential interference with some therapies.


During cancer treatment, diarrhea can occur and deplete the body of necessary fluids and nutrients. Chemotherapy, radiation, bone marrow transplant, medications used for side effect management and cancer itself can contribute to diarrhea. Without normal bowel function, nutritional status can suffer.

It may be uncomfortable discussing your bowel habits with your healthcare team but resolving any problems can improve your tolerance for treatment.

Strategies that I suggest to people to help improve diarrhea include:

• Choose small, frequent meals throughout the day instead of large meals

• Choose low fiber foods and especially limit insoluble fiber from foods such as cruciferous vegetables, leafy greens, and hearty grains

• Choose fruits like bananas, and other canned fruits like applesauce, peaches, and pears

• Drink beverages between meals instead of with meals

• Avoid digestive stimulants like caffeine, ginger, peppermint


Need more insight? Ask your healthcare team for a referral to a registered dietitian or search The Academy of Nutrition and Dietetics for a local dietitian. See AICR’s information and resources for cancer survivorship and healthy living, including Recharge, our monthly newsletter for survivors.

5 comments on “Keeping Your Gut Healthy During and After Cancer Treatment

  1. Rita Sanders on

    It’s good to know that you should increase your fiber intake to around 25 grams because my dad has not been eating that much fiber. He’s finally able to go through treatment so my brother and I are excited. However, we want to make sure that the treatment doesn’t affect him too harshly. I think a good diet will come in handy!

  2. Adam Golightly on

    My aunt thinks that she has holistic cancer and she wants to make sure that she can be treated for it and that it will be able to go away with some work. Getting some treatments from a professional could be really useful for her and allow her to get better faster. Thanks for your tips about how she can keep her digestive tract healthy and allow her to keep up on her health by eating plant fibers that are required by bacteria in the stomach.


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