How cancer can affect your eating

Many people experience eating problems during or after cancer treatment.

Your doctor can refer you to a dietitian who will assess your food needs and advise you on which foods are best for you.

Some eating problems, such as a poor appetite or weight loss, may have been symptoms which led to your diagnosis. Some eating problems may be due to where the cancer is in your body, causing you to feel sick or have poor digestion. Your doctor may try to improve your food intake before treatment starts.

Eating problems can be caused by some cancer treatments. These can be temporary, but sometimes last longer. If you have treatment to your mouth, throat, stomach or intestine, it will take time to return to a regular eating pattern. Treatment such as radiotherapy to the head and neck area may cause a dry mouth and difficulty swallowing. Chemotherapy and targeted therapies can cause sickness, diarrhoea or constipation, taste changes and soreness to your mouth. You could also be at risk of an infection after cancer treatment and your doctor may suggest avoiding foods with harmful bacteria.

How cancer can affect eating

People with cancer have different dietary needs. Some people feel well and able to eat normally. For others, weight loss or a poor appetite were symptoms that led to their diagnosis. If you had eating problems before you were diagnosed, you may need some support from your doctor or dietitian to improve your diet before you start treatment.

Some eating problems may be related to the cancer itself. Depending on where the cancer is in your body, it can cause you to feel sick (nausea), be sick (vomit), or it can cause pain or poor digestion. The cancer may also change the way your body uses the food you eat, so that you don’t get all the nutrients you need.


Qualified dietitians are experts in assessing the food needs of people who are ill. They can review your diet and they will take into account any specialist dietary requirements you have. They can advise you on which foods are best for you, and whether any food supplements would be helpful.

If you have problems with your diet, you can ask your doctor at the hospital to refer you to a dietitian. In some hospitals, you can refer yourself. Contact the hospital’s dietetic department for more information. If you are not in hospital, your GP or district nurse can refer you to a community dietitian, who will visit you at home.

The dietitian I saw twice a week made sure that I was getting enough nutrients to get me back on the road to recovery.


Cancer treatments

Some cancer treatments can cause eating problems. Some problems are temporary and improve when you finish treatment. Others may last longer. Your doctor, specialist nurse or dietitian will support you and advise you on what might help.


Some types of surgery can slow down your digestion. If you have surgery to your mouth, throat, stomach or bowel, you may need to adjust to changes in your eating patterns.


Radiotherapy to your head, neck or chest area can cause:

  • taste changes
  • swallowing difficulties
  • a dry mouth
  • a sore mouth and throat.

Radiotherapy to the tummy (abdomen) or pelvic area (the area between the hips) can make you feel sick or be sick. It can also cause diarrhoea.


Common side effects of some chemotherapy treatments include:

  • loss of appetite
  • taste changes
  • constipation
  • diarrhoea
  • feeling sick or being sick
  • a sore mouth.

Targeted (biological) therapy

Targeted therapies can affect your appetite or your ability to eat. Problems might include:

  • taste changes
  • a dry or sore mouth
  • feeling sick.

I found that during and after chemo my taste buds were all messed up, it took a couple of months for things to drift back to as they were.


I experienced taste changes quite early on during my chemo. It put me off eating. But I still made sure that I ate healthy and nutritious food to keep my strength up.


Risk of infection

Cancer or treatments for cancer may increase your risk of infection. Some treatments can temporarily lower the number of white blood cells in your body that help fight infection. Having a lower number of white blood cells than normal is called neutropenia.

Most people having cancer treatment will not need to change their diet. If you are having high-dose chemotherapy, you may be advised to avoid foods that might contain harmful bacteria. You may also need to be extra careful with food hygiene. This is called a ‘clean diet’. It can help reduce your risk of getting an infection. Your specialist nurse will discuss this with you.

Foods to avoid if your immunity is low

If your immunity is very low, you might need to avoid certain foods. Your doctor, nurse or dietitian will be able to tell you whether you need to avoid any of these foods:

  • cheeses made from unpasteurised milk (and other foods or drinks made from unpasteurised milk)
  • mould-ripened and blue-veined cheeses
  • liver pâté
  • yoghurt or other products that contain probiotics
  • fresh salads
  • raw meats and seafood
  • runny eggs.

We have more information about reduced immunity and avoiding infection.

Special diets

Some people with cancer may have specific eating problems, for example:

  • people with diabetes
  • people who have a colostomy or ileostomy
  • people who have had all or part of their stomach or bowel removed
  • people who have had radiotherapy to their mouth or jaw.

If you have any of the above, you may need to follow a special diet. Your doctor, specialist nurse or dietitian can give you advice.