What is chemo belly?

Dr Sarita Retief explains what chemo belly is, what it could be caused from, and how it would be treated.

You can listen to this article below, or by using your favourite podcast player at pod.link/oncologybuddies

Chemo belly is a non-medical term for discomfort, bloating, and abdominal distension that some people experience when having chemotherapy. Multiple factors can contribute to this feeling and if you feel distressed by this, your oncologist would evaluate the following:

1. Find out what were the baseline symptoms before chemotherapy was started. Did you have any food allergies like gluten or lactose intolerance to start with? If you have always had an irritable bowel, then it will help to go onto a FODMAP diet. There are multiple apps and websites that will help you limit the effects of these food intolerances.

FODMAP is an abbreviation of five naturally occurring sugars (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) that are not well absorbed by your small intestine. They reach the colon where gut bacteria then use these sugars to produce hydrogen gas. This causes discomfort, bloating, and sometimes diarrhoea.

2. The type of cancer you have. Gastric cancers can easily make you feel full quickly, cause bloating, excessive burping, and upper abdominal discomfort. Colon cancer can cause cramps, bloating, diarrhoea, and constipation. Any cancer in the abdominal cavity (in between bowels) can cause delayed movement of the bowels, bloating, distention of the abdomen, and nausea or vomiting. This is not strictly chemo belly, but can be confused as side effects of treatment.  

3. Some cancers don’t cause bowel symptoms directly, but have secondary effects that cause bowel symptoms. These include NETs that excrete substances that can cause diarrhoea and cramping. Pancreatic cancers can cause too little pancreatic digestive enzymes to be secreted, leading to diarrhoea, and foul smelling stools that are difficult to flush. Any cancer affecting the liver or bile ducts can cause nausea and intolerance to fatty food.  

4. Were you exposed to antibiotics recently? This causes disruption of the microbiome that leads to nausea, bloating, diarrhoea, and cramps. Sometimes there can be an overgrowth of a specific bacteria called clostridium difficile. Stools need to be specifically tested for this, and a targeted oral antibiotic should be given.

5. What chemotherapy are you on? Some chemotherapies are more likely to disrupt the microbiome. Others can specifically slow down the peristalses of the bowel and cause severe constipation. Others can cause severe diarrhoea. The nausea medication that is given with the chemotherapy can also cause either diarrhoea or constipation.

6. What does your diet consist of? Some patients’ diet consist of litres of soft drinks per day and ultra-processed foods. Their microbiome is suffering from this.

How to limit the effects of chemo belly

Discuss your symptoms with your oncologist.

Fibre is the staple food of your good gut. During stressful times, ensure that this fibre is more easily digestible.

Ensure proper hydration. No other drinks beat water to be the most beneficial for your health. Soft drinks, fruit juice, and diet drinks are not healthy.

Limit your sugar intake extremely. Any sugary foods will cause more growth of the bad bacteria. Foods made with flour are also converted  to sugar in your blood. Artificial sweeteners are also perceived as sugar by your body.  

Fresh food is most beneficial. All food made in factories has molecules that are not known to these gut bacteria. Avoid any food with additives and stabilizers.  

Gut bacteria must not be overfed; keep a healthy weight and have periods of fasting.

Keep active as much as tolerated. This will help prevent constipation.  

Good gut bacteria thrive when your body has a predictable biorhythm. That means good sleep and going to bed and getting up at the same time.  

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