How does cancer affect diet and nutrition?

Whether it’s someone currently going through cancer and receiving treatment, or someone who has been given the all-clear, diet and nutrition is something that can be affected during both these times. Varying factors can shape what type of diet someone now has. Some food groups may now need to be avoided, while others can be encouraged and what once tasted sweet might now taste sour.

However, every cancer experience is different and what diet works for one person might not work for another.

Our Cancer Care Team, for members, share what they’ve heard in their daily roles and the questions most asked when it comes to all things nutrition.

Adapting your diet

Different cancer types and treatments mean different side effects and symptoms, as well as possible changes to appetite and taste. Diets might therefore need to be adapted, as what someone would usually eat might now not be possible.

For example:

Colorectal cancers – people can have issues with going to the toilet more frequently after treatment, as some foods can upset how the bowel works. Cancer Research UK highlights the foods most likely to cause issues:

• very high fibre fruits and vegetables
• pulses, such as baked beans or lentils
• fizzy drinks, beer and lager
• very rich or fatty foods¹

A low fibre diet therefore may be advised for around 6 weeks, with the aim to increase fibre on a gradual basis after this time.

Head, neck and mouth cancers – this type of cancer can make swallowing and eating difficult and painful. If someone has had surgery to remove part of their mouth or neck, then eating solid foods post-surgery isn’t likely.

Once released from hospital, soft foods such as mashed potato, porridge or soups, may need to be eaten while the affected area heals, and chewing becomes less painful.

Radiotherapy can also affect eating. It may make muscles and tissue in the throat and gullet weaker and less stretchy. This can make it harder to swallow some foods or cause certain foods to stick in the throat. If nerves that control the muscles in the gullet are affected, they may be less able to move food downwards.²

Depending on the treatment or surgery, a dietician or speech and language therapist can help support with eating and rehabilitation might be offered to those having difficulties swallowing.

Weight loss

Weight loss is common in people with cancer, as the cancer can cause a loss of appetite, pain when eating, nausea or vomiting. There are also some cancers that make weight loss even more common.

About 60% of people with lung cancer have a loss of appetite and significant weight loss at the time of their diagnosis. In people with upper gastrointestinal cancer, this number is 80%. Upper gastrointestinal cancers include:

• food pipe (oesophagus) cancer
• stomach cancer
• small bowel cancer
• pancreatic cancer
• liver cancer (including primary and secondary liver cancers, bile duct and gallbladder cancer)³

Treatments that can also cause weight loss

Chemotherapy – common side effects are loss of appetite, feeling sick or vomiting, infections and a sore mouth. To help combat these, anti-sickness medications can be given to prevent nausea, and pain relief or special mouthwash can be given to help a sore mouth. It's also advised to avoid spicy, salty or sharp foods.⁴

Radiotherapy – similar side effects to chemotherapy can occur for those who have had radiotherapy on their head and neck or stomach. Like chemotherapy, it can also cause tiredness which can lead to a loss of appetite.

Surgery – post-surgery, people may not feel like eating or have any energy to cook, leading to weight loss.

Tips to help regain weight

Being underweight can cause lower levels of vitamins and minerals and can also affect how well the immune system works. Increasing the chance of infection and slowing down recovery.⁵

Tips to help put weight on in a healthier way, rather than reaching for foods high in sugar or saturated fats include:

• Eat little and often, rather than sticking to three meals a day – this can also help with feelings of nausea.
• Add in high calorie or high protein foods into what you already eat – for example adding cream or peanut butter into porridge or whole milk into tea and coffee.
• Eat healthy fats such as avocado, nuts and oily fish. Dieticians will usually be available after cancer surgery or treatment and can help offer guidance on what food and type of diet is best.

Once you’ve regained weight, start to cut down on the higher-calorie foods so that you stay at a healthy weight.⁵

A change in taste and flavours

Experiencing a change in taste is common in cancer.⁶ Those who have had chemotherapy might experience a metallic taste or may not be able to taste at all, which can make some people go off certain foods they used to like.

Tips to help enhance flavour and regain taste include:

• Putting nutmeg or ginger in water can help improve the taste of it.
• Having a small amount of pineapple juice can help clear out the taste buds and bring back the ability to taste flavours. Although pineapple should be avoided when taking certain medications, so please read the patient information leaflet or ask your GP before eating or drinking it.
• Add strong-flavoured ingredients to your meals – such as lemon or lime into yoghurt (citrus can aggravate a sore mouth if eaten alone), onion, mustard, spicy sauces and strong herbs like basil or garlic.⁶
• Avoid using metal cutlery if food tastes metallic and make sure to keep your mouth clean and brush your teeth well.⁷

Some people will avoid their favourite foods until their taste is back to normal or avoid hot or cold foods, but as Cancer Research UK states “there aren't any rules about what you should and shouldn't eat, if you feel like it, try it.”⁷

The same goes for what diet is followed after treatment and beyond. The type of cancer can help determine what foods can or can’t be eaten, so what works for one person doesn’t work for another, as every cancer experience is unique.

Resources

• Weight changes and cancer – Maggie's.org
• How can I help reduce my risk of getting cancer? - AXA Health
• Cancer Diets: Myths and More - British Dietetic Association

References

1. Eating and bowel cancer – Cancer Research UK
2. How treatments can affect chewing and swallowing – Macmillan
3. Weight loss and cancer – Cancer Research UK
4. Chemotherapy side effects – NHS
5. Healthy weight gain: how to gain weight after illness – British Heart Foundation
6. Taste changes – World Cancer Research Fund
7. Appetite, taste changes and cancer drugs – Cancer Research UK