Nutrition-related side effects of chemotherapy

Robyn van der Westhuizen lists ways to deal with nutrition-related side effects caused by chemotherapy.

Chemotherapy targets cancer cells, but it can also affect healthy cells involved in digestion, taste, and appetite. These side effects may make eating difficult and can lead to weight loss, muscle loss, dehydration, and fatigue.

The goal of nutrition support during chemotherapy is to help maintain strength, body weight, and quality of life while making eating as manageable as possible.

Poor appetite and early fullness

Loss of appetite and feeling full quickly are common side effects during chemotherapy. This may result from nausea, changes in taste, fatigue, or treatment-related inflammation.

When appetite is low, eating by the clock rather than by hunger is helpful. Small, frequent meals or snacks (5–6 per day) are usually better tolerated than large meals.

Choosing energy- and protein-dense foods, such as full-cream dairy, eggs, nut butters, and fortified meals, helps meet nutritional needs even when intake is limited.

Limit large drinks with meals; have most fluids between meals so you don’t fill up on liquid.

Nausea and vomiting

Chemotherapy can irritate the stomach and trigger nausea or vomiting. Anti-nausea medication prescribed by the oncology team is essential.

From a nutrition perspective, small portions eaten regularly are often easier to tolerate. Bland, easy-to-digest foods, such as white toast, crackers, porridge, rice, or mashed potatoes may help.

Cold or room-temperature foods often cause less nausea than hot foods, as strong smells can worsen symptoms.

Sipping fluids frequently in small amounts helps prevent dehydration.

Taste and smell changes

Taste changes are common and can include metallic, bitter, overly sweet, or bland flavours. These changes may reduce the enjoyment of food and lead to the avoidance of protein-rich foods, particularly red meat.

Using plastic cutlery may reduce metallic tastes. If beef is unappealing, use alternative protein sources, such as eggs, chicken, fish, dairy, beans, or lentils.

Mild flavourings, herbs, marinades, or sauces may improve palatability. Let hot dishes cool slightly; choose cold foods (yoghurt, smoothies, egg mayonnaise, cottage cheese, chilled fruit). Heat can intensify strong tastes.

Sore mouth and mouth ulcers

Chemotherapy can cause inflammation or ulcers in the mouth and throat, making chewing and swallowing painful.

Soft, smooth, moist foods are best tolerated, such as yoghurt, custard, scrambled eggs, mashed potatoes, soups, stews, and fruit purées.

Acidic, spicy, rough, or crunchy foods may worsen pain and should be avoided if they cause discomfort.

Eating foods that are cool or lukewarm rather than hot can reduce discomfort.

Maintaining good oral care is essential for supporting healing and reducing the risk of infection.

Diarrhoea

Chemotherapy can disrupt the lining of the gut, impairing fluid and nutrient absorption.

It may also alter the balance of healthy gut bacteria and increase bowel activity, causing the intestines to move more quickly and resulting in looser, more frequent stools.

Maintaining fluid intake is critical, using water, diluted juices, clear broths, or electrolyte drinks.

Small, frequent meals are usually better tolerated.

Low-fibre, low-fat foods, such as white rice, bananas, applesauce, cooked vegetables, and lean proteins, may help until symptoms settle.

Constipation

In some cases, treatment may slow bowel movement, while supportive medications, such as anti-nausea treatments, pain medication, and iron supplements, can worsen constipation.

Poor appetite, nausea, and changes in taste may reduce food and fluid intake, leading to low fibre intake and dehydration.

Fatigue can limit physical activity, and changes in daily routine or hospital stays can further disrupt normal bowel habits.

Gentle soluble fibre (oats, psyllium husk, cooked vegetables, or stewed fruit), adequate fluids, and light movement as tolerated can help support bowel regularity.

Gut-friendly jelly

Give this gut-friendly jelly a try; mix it, chill it, and enjoy one teaspoon in your smoothie, oats, or yoghurt for a happy, easy-going tummy!

• 3 teaspoons of psyllium husk
• 150ml fruit juice
• Add lemon or lime to make it sour – if tolerated.
• Place in the fridge for 10 minutes before consuming.

Robyn van der Westhuizen is a clinical dietitian who works at Life New Kensington Rehabilitation Clinic and Life Bedford Gardens Hospital, and runs NutraConnect, her own private practice that supports patients at home, including those needing palliative care during cancer treatment. 

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