During oncology treatment, maintaining proper nutrition is necessary for supporting immune function, strength, maintaining good quality of life, and promoting recovery. To help meet baseline calorie and protein needs, patients are encouraged to eat small, frequent meals that are high in protein and calories, and to stay well-hydrated throughout the day. Treatments such as chemotherapy and radiation can cause side effects, two of which can be constipation and diarrhea, these can impact a patient’s ability to eat well.
| Constipation |
Constipation is a common side effect of treatment, often linked to reduced physical activity, dehydration, or the use of medications such as pain and nausea regimens. To help manage constipation, it’s recommended to increase fluid intake and consume foods high in insoluble fiber. Good sources of insoluble fiber include fresh fruits and vegetables with skins, whole wheat/ grain foods, nuts, seeds, and crunchy nut butters.
Insoluble fiber helps to promote regular bowel movements. Gradual physical activity, such as walking, can also assist in stimulating digestion. However, it’s important to introduce fiber gradually to avoid GI symptoms (i.e. bloating, abdominal discomfort), and to always pair fiber intake with adequate fluids. Talking with a Registered Dietitian, clarity on fluid goals throughout the day can be identified.
| Diarrhea |
On the other hand, diarrhea may occur due to the effects of treatment on the gastrointestinal lining or as a result of certain medications. In this case, high-fiber foods—especially insoluble fiber—may worsen symptoms. Instead, patients are encouraged to eat a low-fiber diet temporarily and focus on soluble fiber, which helps absorb excess water in the intestines, bulk stool, and slow digestion. Good sources of soluble fiber include bananas, applesauce, oatmeal, white rice, and potatoes. Hydration is equally crucial, and patients should sip clear fluids such as broth, electrolyte containing beverages, or diluted juices to prevent dehydration. In some cases, anti-diarrheal medications may be necessary under the guidance of a licensed healthcare provider.
Because every individual response to treatment is unique, it’s important to work with a Registered Dietitian or oncology care team to tailor dietary choices based on nutrition related symptoms. Monitoring fiber intake—both the type and the portion size—can play a key role in managing gastrointestinal side effects of treatment and maintaining overall health during a patient’s cancer journey.
References:
Nutritional Management of Oncological Symptoms: A Comprehensive Review - PMC
Oncology Nutrition for Clinical Practice AND Textbook (Maureen Leser, Natalie Ledsema, Sara Bergerson, Elaine Trujillo)