Diet and cancer

A college of photos of our Oncology Dietitians

Oncology dietitians play an integral role in helping you if you are struggling to eat and are losing weight during your treatment. We also help in providing advice on managing the side effects of your treatment and your cancer so that we can improve your nutritional wellbeing.

The videos and information on this webpage will provide you with evidence-based advice to support you during your cancer treatment. 

The importance of eating well during cancer treatment

Why is it important to eat well during cancer treatment?

Cancer treatments disrupt the way cancer cells grow and divide but they can also affect normal cells. This can cause you to feel unwell. It is therefore very important to have a healthy balanced diet appropriate to your specific needs during your treatment to keep you as well as possible. This can help you recover faster  and support your body during your treatment.

Why is it important for me to keep my weight stable during my treatment?

Research has shown that people who maintain a stable weight through cancer treatment live longer and have better quality of life. It is therefore important not to lose weight during your cancer treatment even if you are overweight.

If you lose weight during treatment:

  • You are more likely to lose muscle than lose fat. This puts you at risk of poor mobility and may reduce your ability to do things that you enjoy.
  • You may be more at risk of side effects, and your treatment may have to be delayed if you are not well enough.
  • Your body shape is likely to change. If you are having radiotherapy the radiographer will mark your body with permanent ink dots before your treatment starts. If you lose weight, the treatment may not reach the targeted tumour cells and may affect normal tissue. This could lead to increased side effects so it is best to keep your weight stable.

Are there any foods I need to avoid? 

Your doctor, nurse or dietitian will let you know if there are any specific foods you need to avoid with your particular treatment. Most people do not need to cut out any foods from their normal diet.

Healthy eating during treatment

Why should I eat a healthy diet? 

You should follow a healthy diet if:

  • You are coping well with treatment
  • You are not suffering with side effects or symptoms that are affecting your food intake
  • If you have not lost weight
  • If you have gained weight during your treatment

If you are managing well with your cancer treatment and are not having problems with eating and do not have a poor appetite you should aim to have a healthy balanced diet and keep your weight stable.

Your diet should include a selection of foods from each of the following food groups:

  • Fruit and vegetables.
  • Starchy foods (carbohydrates), such as wholemeal bread and wholegrain cereals.
  • Protein-rich foods such as beans, pulses, meat, fish and eggs.
  • Dairy or calcium containing foods.
  • ‘Good’ fats from vegetable sources e.g. olive and rapeseed oil, nuts and seeds.

Foods which are high in sugar or high in saturated (animal) fats should be limited if you have a good appetite. These foods provide a large amount of energy to our diets which can result in weight gain.

The Eatwell Guide diagram gives an idea of the recommended proportions of each food group - access it here.  

Important tips for a healthy lifestyle

  • Eat at least 5 portions of a variety of fruit and vegetables every day.
  • Include starchy carbohydrates in each meal e.g. rice, potatoes, bread, pasta. Try to choose wholegrain options where possible.
  • Include dairy or dairy alternatives (e.g. soya) to provide calcium and other vitamins and minerals.
  • Include protein in your diet e.g. pulses, fish, eggs, meat, poultry and vegetarian alternatives (tofu, Quorn®)
  • Try to increase the amount of pulses (beans, peas and lentils). They are high in fibre and protein, as well as vitamins and minerals. These provide a good alternative to meat as they are low in fat.
  • Have 2 portions of fish per week, one of which should be oily (e.g. salmon, mackerel, herring).
  • Choose unsaturated (vegetable) oils and spreads such as olive or rapeseed oil, avocado, nuts and seeds. Be careful to ensure these are eaten in small amounts as they are very high in calories.
  • Drink approximately 8 cups/glasses of fluid a day. This can include water, low calorie squash, tea and coffee. If drinking fruit juice limit to 150ml maximum per day. Avoid drinks containing added sugar such as high juice, and non-diet versions of fizzy drinks.
  • Try to eat at regular mealtimes as this can help you to avoid feeling very hungry, and overindulging or reaching for high fat/sugar items.
  • Do not exceed 14 units of alcohol per week (for men and women) with at least 2 alcohol free days. Most alcoholic beverages are high in calories and contain no/minimal amounts of other nutrients. 1 unit = 250ml 4% beer (~half pint), 25ml 40% spirit, 76ml 13% wine. Try and save alcohol for celebrations rather than regular drinking.

For further advice on healthy eating and drinking:

Read information from Macmillan on healthy eating and cancer here.

Read information from Cancer Research UK on diet and cancer here

Read information the World Cancer Research Fund here.

Weight gain during treatment

What should I do if I am gaining weight during my treatment?

If you start to gain weight once your treatment starts, aim to follow a healthy balanced diet.

Having cancer can change lots about your life, including your eating. You might not be cooking as much. Or you might not be as physically active as you were before. When you are having active treatment it is important not to go on a “diet”.

In addition to the healthy eating advice above you might find the following tips useful:

  • Fill half you plate with salad or vegetables at your main meal.
  • Smart snacks, if you are hungry between meals choose healthy options such as a piece of fruit, yoghurt or a small handful of nuts.
  • Try to stay organised. Have healthy snack options with you to avoid reaching for an unhealthy option when out and about.
  • If you have given into temptation don’t dwell on it. Everyone has days where they struggle to eat as healthily as they plan to. Don’t let this take over your day or your week. Put it behind you and move on!

Poor appetite and weight loss during cancer treatment

What should I do if I’m losing weight or struggling to eat properly?

When you are having cancer treatment you should aim to stay a stable weight. If you are losing weight you may need to make some changes to your diet. Our Patient Information Leaflets Eating when you have a small appetite and Healthy eating for weight gain will give you helpful ideas.

If your appetite is reduced it is important to make the most of each mouthful of food. There are several ways you can do this.

1. Choose foods high in energy

It is a good idea to focus on the foods that are high in energy (calories). These are often foods that you may have previously avoided e.g. cheese, full fat milk, custard, creamy soups, nuts etc.

2. Fortify your food

Adding nourishing extras to the foods that you eat can make each mouthful more wholesome. It will increase your energy and protein intake without the need for having a bigger portion.

Try to enrich food and drinks by adding extra ingredients using the table below:

Add sugar, jam, honey to 
  • Cereal or porridge 
  • Puddings
  • Hot Drinks 
  • Milkshakes or smoothies 
Add extra fats (e.g. butter, margarine, spread, oils, mayonnaise) to
  • Mashed potato or pasta dishes 
  • Toast or bread 
  • Sauces 
Add cream, creme fraiche, full cream milk to 
  • Sauces and soups 
  • Mashed potato or pasta dishes 
  • Puddings, pastry and cakes 
  • Cereal or porridge 
  • Milkshakes or smoothies
Add grated cheese to 
  • Sauces and soups 
  • Mashed potato or pasta dishes 
  • Pizza
  • Scrambled eggs or omelettes 
  • Beans or spaghetti on toast 
Add skimmed milk powder to 
  • Milk 
  • Porridge 
  • Mashed potato 
  • Creamy sauces and soups 
  • Custard and milky puddings 
  • Milkshakes 
Add cream, evaporated or condensed milk, yoghurt, crème fraîche, custard or ice cream to
  • Puddings and desserts 
  • Fruit, fruit pies or crumbles 
  • Jelly, cakes and pastries 

Fruit and vegetables are an important source of vitamins and minerals, however they can fill you up quickly and are not rich in energy or protein. Adding butter, cheese or creamy sauces to vegetables; mayo, salad cream and full fat dressings to salad; and cream, custard or ice cream to fruit can make them more nourishing.

 3. Eat regular snacks 

It is common to get full more quickly when your appetite is poor. It can be helpful to have 5-6 smaller meals and snacks through the day instead of 3 larger meals.

Snacking is a great way to eat more without needing to increase your portion sizes. It can be helpful to eat whilst in front of the TV or reading a book as this will distract you and may allow you to eat more.

Examples of nourishing snacks include:

  • Individual portions of cheese
  • Slice of ham or salami
  • Mini sausage rolls or scotch eggs
  • Mini spring rolls or samosas
  • Breadsticks or tortilla chips with dips
  • Handful of nuts or dried fruit
  • Crisps
  • Mini chocolate bars or cakes
  • Biscuits
  • Cream cakes and pastries
  • Yoghurts
  • Individual sized puddings e.g. crème caramel, mousse, trifle
  • Small pot of custard
  • Rice pudding
  • Ice cream
  • Toast with lots of butter, peanut butter, jam, honey or chocolate spread

4. Drink nourishing fluids

Water is good for hydration, but it does not contain any calories or protein. Other drinks such as fruit juice, full sugar squash and milky drinks such as milk shakes, Horlicks®, hot chocolates and lattés are good for hydration and they will also be nourishing. You should aim for 8-10 cups of fluid per day. These should be a mix of water and nourishing fluids.

Managing symptoms and side effects

What can I do to manage symptoms that are affecting how I am eating?

The symptoms and side effects of cancer treatment may cause you to lose your appetite. It is important to discuss this with your doctor or specialist nurse, since there may be medications they can prescribe to help you.


If you are opening your bowels less frequently than usual and your stools are hard and difficult or painful to pass, you may be constipated. Constipation is a common side effect of cancer treatment, anti-sickness drugs and painkillers. Constipation can be very serious and cause symptoms such as tummy pain, nausea, vomiting and poor appetite.

Dietary changes may not be sufficient to relieve constipation caused by medicines. You are likely to need to take laxatives. Please consult your doctor or specialist nurse for advice.

If you are constipated follow the advice below:

  • Aim for at least 2 litres of fluids per day. This can include water, tea and coffee, squash, fruit juice and milky drinks.

  • Gentle exercise can help to stimulate the bowels. Keep as active as possible through your treatment.

  • You may need to increase the fibre in your diet. Good sources of fibre include: fresh fruit and vegetables, dried fruit and wholegrain products. Please be aware that a high fibre diet is not suitable for everyone. Consult your doctor or dietitian if you are unsure about the amount of fibre you should have.


Diarrhoea is a common side effect of many cancer treatments. It is unlikely due to the type of food you are eating. Please discuss this with your doctor or specialist nurse who will be able to prescribe suitable medications if appropriate.

Diarrhoea may also be a sign of infection. Check your temperature and alert your medical team if you are worried about your symptoms.

It is important to keep well hydrated when you have diarrhoea as you may be losing a lot of fluid.

  • Aim for at least 2 litres of fluids per day. This can include water, tea and coffee, squash, fruit juice and milky drinks.
  • Diarrhoea is usually caused by treatment, and it is not usually necessary to remove fruit and vegetables from your diet.
  • Aim to eat small frequent snacks throughout the day to avoid losing weight
  • Isotonic sports drinks (e.g. Powerade®, Lucozade sport®, Gatorade®) and rehydration medications (e.g. Dioralyte®) may be required if the diarrhoea is severe and goes on for a long time.

Dietary changes may be useful in some cases. If your symptoms are ongoing ask your doctor or your specialist nurse to be referred to a dietitian.

Nausea and vomiting

Chemotherapy and some medications can cause nausea and vomiting. It is not usually related to the food you are eating. Your doctor or specialist nurse can advise you on anti-sickness medications. You may need to try several before you find the one that suits you.

You can also follow these tips to reduce nausea and increase what you are managing to eat:

  • Try eating dry, bland foods first thing in the morning to settle your stomach. You may find it helps to nibble a biscuit before getting out of bed in the morning.
  • Eating little and often can be helpful. Nausea can be worse if you are either very hungry or too full.
  • If cooking smells make you feel sick, try eating cold foods. If you prefer a hot meal, ask somebody else to do the cooking. You can also use microwave or oven ready meals so you don’t need to be in the room whilst they are cooking.
  • Make sure the room you are eating in is well ventilated. Open the windows so that food smells don’t linger.

Taste changes

Cancer and cancer treatments can cause your taste to change in the following ways:

  • sweet or salty foods become stronger in flavour
  • things you previously liked, you are now unable to eat
  • you have found a taste for other foods you previously disliked
  • a complete loss of taste
  • food tastes very metallic.

It is important to try and eat as normally as possible even if food tastes strange. Missing meals due to altered taste can lead to weight loss.

Taste changes can come and go, so it is best to try and have what you fancy at the time. Avoid foods that don’t appeal, but try them again in a few days or weeks as your taste is likely to continue to change and you may enjoy them again.

Follow these tips to cope with taste changes:

  • If you find you prefer stronger flavours, try adding herbs, spices, sauces and pickles to food.
  • Some people find cold food tastes better than hot. Cold foods also often smell less strong if food smells are off-putting to you.
  • Sharp tastes such as fruit, fruit juices and boiled sweets can be refreshing.
  • You may find tea and coffee no longer taste the same. Try herbal teas, squash or fizzy drinks instead.
  • If you have a metallic taste in your mouth you may find it more pleasant to eat using plastic cutlery.
  • If you are struggling to eat meat, try other sources of protein such as fish, eggs, tofu, beans or dairy products.

Taste changes can also be a result of a dry mouth or oral thrush. If you notice your tongue has a thick white or yellow coating, contact your doctor or nurse specialist. They may be able to prescribe medication to help you.

Dry mouth

A dry mouth is common during some cancer treatments. A dry mouth can allow bugs to build up. It is therefore important to frequently brush your teeth and use mouthwash. If your tongue has a thick white or yellow coating please discuss this with your doctor or specialist nurse who will be able to prescribe mouth washes or medication to help.

Tips to cope with a dry mouth:

  • Aim for at least 2 litres of fluids per day. This can include water, tea and coffee, squash, fruit juice and milky drinks.
  • Choose soft foods. These will be easier to chew and swallow.
  • Add sauces and gravy to meals.
  • Avoid dry foods e.g. crackers, bread.
  • Use sugar free chewing gum. This can help to stimulate your saliva.
  • Suck on boiled sweets to stimulate saliva.

Sore mouth / ulcers in the mouth

It is important to speak to your doctor or specialist nurse if your mouth becomes sore. This can be a sign you may be developing mouth ulcers. Treating this early can stop it from getting worse.

Tips to cope with a sore mouth:

  • Choose soft foods since these will be easier to chew and swallow.
  • Opt for smooth puddings to increase your energy intake e.g. custard, mousse, yoghurt.
  • Add sauces and gravy to meals.
  • Avoid hot foods. Opt for warm, cold or frozen foods instead.
  • Avoid dry foods e.g. crackers, bread.
  • Avoid spicy foods e.g. chilli, curries.
  • Avoid acidic foods e.g. fruit, tomatoes.

Tiredness / fatigue

Feeling very tired is a common side effect of cancer treatment and can make shopping, cooking and eating more challenging. One of the best ways to help with fatigue is to try and do some gentle activity every day. This has been shown to help with energy levels. E.g. go for a short walk round the block, gentle house work or gardening.

Tips for coping with tiredness / fatigue:

  • Frozen, tinned and ready meals can be useful on days when you feel tired. They can be just as nutritious as homemade meals and are much easier.
  • Plan ahead. On days when you are feeling well, stock up the cupboards and freezer with easy meals and snack options.
  • Let family and friends help you with shopping and cooking.
  • If you are really too tired to have a meal, eat a sandwich, snack or nourishing drink instead e.g. hot chocolate, milkshake, smoothie. Don’t be tempted to go to bed without eating as you will feel much weaker and more unwell when you wake up.

Stress and anxiety

Cancer treatment can be very stressful and frightening. You may find that this puts you off eating. Changes in your eating patterns may also cause you and those around you to worry. It can be helpful to talk to those close to you, or a counsellor about how you are feeling about your illness and treatment.

The Fountain Centre (found in St Luke’s Cancer Centre) offers advice, counselling and a range of complementary therapies, in a calming and relaxed atmosphere.

There are a number of meditation apps on Android and Apple devices which you may also find useful. Learning “Mindfulness” is currently very popular for stress relief. 

It can be very difficult for family and friends to see somebody they care about struggle to eat. You may find that family members insist on giving you big portions of food because they want to help you. It can be helpful to talk through any problems you are having with eating with those around you. This will help them to understand why you are eating differently. Explain that a smaller portion of food is easier, and that you are likely to eat more if your plate is not too full.

Try not to put too much pressure on meals. Make sure you have a calm, pleasant space to eat in. Some people find being distracted with the television, music, a book or a crossword helps them to eat more without realising.

Alternative diets

Can alternative diets be helpful?

There is a lot of attention in the media surrounding diets to “beat cancer”. This includes a lot of speculation about foods that “cure” or “feed” cancer. There is currently no scientific evidence that any of these popular diets improve cancer survival or quality of life.

Some of these ‘diets’ restrict whole food groups (e.g. dairy and gluten), when there is no need to. This puts you at risk of nutritional deficiencies and weight loss which may compromise your cancer treatment.

Alternative diets are therefore not recommended. If you are still keen to follow a particular diet, please discuss this with your doctor or nurse or ask to see a dietitian to ensure your diet is nutritionally complete.

Vitamin and mineral supplements

Do I need vitamin supplements?

If you are eating a healthy balanced diet and have not lost weight, you should not need to take any extra vitamin and mineral supplements during your cancer treatment. Vitamin and mineral supplements can be helpful if you are struggling to maintain a balanced diet or have problems absorbing your food properly. These can be prescribed by your doctor if they suspect that you are lacking a particular vitamin or mineral.

Alternatively they can be bought at most pharmacies and supermarkets. A one-a-day Multivitamin and mineral tablet is recommended. Choose products that have no more than 100% of your recommended nutrient intake (RNI) for each vitamin and mineral.

It is now recommended that everyone takes a Vitamin D supplement of 10 micrograms (mcg) or 400IU per day during the winter months from October to April.

High dose vitamin and mineral supplements are not recommended as they may interact with your cancer treatment. Avoid taking supplements such as Berrocca, 500mg or 1000mg Vitamin C, 15mg or 25mg Zinc.

Herbal supplements are also not recommended during cancer treatment. They are not always tested and may cause an interaction.

If you are already taking a vitamin, mineral or herbal supplement that is not prescribed, or want to buy an over-the-counter product, always check with your doctor, nurse or dietitian that it is safe to use during your treatment.

Food safety advice

What food safety advice do I need to follow?

Cancer treatment can make you more prone to illnesses such as food poisoning. The following advice will help prevent you becoming unwell:

Buying food

  • Buy foods in small, individual packets. Avoid large packets that will be open for longer and increase the chance of bacteria contaminating them.
  • Always check ‘use by’ and ‘best before’ dates on packaging.

Storing food

  • Store raw or defrosting meat or fish at the bottom of the fridge in a covered container to stop it dripping or leaking into the fridge.
  • Never refreeze thawed food.

Preparing food

  • Always wash your hands with warm water and soap before preparing food.
  • Keep pets away from work surfaces, food and your dishes.
  • Make sure any cloths or sponges are regularly bleached, disinfected or changed.
  • Avoid cross-contamination of food by changing or washing chopping boards and utensils between raw and cooked food.
  • Disinfect work surfaces regularly.
  • Wash fruit and vegetables before eating.
  • Wash the roof and inside of your microwave regularly.
  • Thaw meat and poultry in the fridge and not at room temperature as bacteria grow quickly at room temperature.

Cooking and reheating

  • Cook all food thoroughly and make sure it is piping hot all the way through.
  • Do not reheat cooked rice. Eat rice as soon as it is cooked.
  • Eat reheated food within 24 hours of preparing or defrosting it. Do not reheat food more than once.

There is no longer any evidence to support the use of neutropenic diets if your white blood count is low. However it is particularly important to follow the food safety advice above to prevent food poisoning.

Diet after cancer treatment

What do I eat at the end of my cancer treatment?

If you have finished your treatment and have no problems with eating, it is advisable to return to a healthy balanced diet. This will help you to recover and to reduce your risk of a recurrence of your cancer.

For further advice on healthy eating and drinking:

Read information from Macmillan on healthy eating and cancer here.

Read information from Cancer Research UK on diet and cancer here

Read information the World Cancer Research Fund here.

If you continue to experience difficulties eating, then continue to follow the advice you have been given by your dietitian until you are able to eat more normally. If you are worried about ongoing poor appetite, or symptoms, please discuss this with your doctor, specialist nurse or dietitian.