Why Does Radiation Cause Diarrhea?

One of the unfortunate side effects of radiation therapy for cancer patients is the development of diarrhea. Any patient receiving radiation treatment to the area around the abdomen, pelvis, or rectum, is bound to experience some intestinal inflammation and, consequently, diarrhea. To combat diarrhea, certain foods should be ingested, and certain foods avoided.

Why does radiation cause diarrhea?

• The large and small bowels are very sensitive to radiation, and large doses of radiation are usually needed to treat tumors around the area of the abdomen and pelvis. With the proximity of the bowels to this area, diarrhea is likely to occur because of radiation treatments.
  Other factors, in addition to the amount of the radiation dose and the extent and size of the tumor, can affect the development of diarrhea in cancer patients receiving radiation treatments. For example, poor nutrition and high blood pressure will contribute to the development of diarrhea in cancer patients receiving radiation therapy.

Foods that contribute to diarrhea

• Certain foods will help cause diarrhea and should be avoided, including milk, milk products, nuts, seeds, fried foods, fresh and dried fruits, fruit juice, raw vegetables, pastries, caffeinated beverages. Spicy foods should also be avoided, as well as alcohol and tobacco. Some food supplements are necessary for patients who are protein- or calory-depleted during treatment and, because they are soy- or milk-based, they can also contribute to the development of diarrhea.

Foods to eat to alleviate diarrhea symptoms

• Some foods are useful for protecting against diarrhea, including fish and poultry, bananas, applesauce, apple juice, white bread, pasta, boiled or baked potatoes, and mild cooked vegetables. It's also a good idea to drink as much water as possible to avoid dehydration.

Minimizing the impact of diarrhea

• Radiation technologists can reduce the potential impact of diarrhea by targeting radiation to confined areas so as to reduce the area that is being exposed to radiation. They can also position patients in such a way to radiation therapy so that as little of the small bowel as possible is affected by radiation.

How long will it last

• The symptoms could last several weeks after a patient finishes radiation treatments. During that time the patient should continue to take any antidiarrhetic prescribed by his physician and maintain a strict diet.