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Common nutritional problems and cancer

Read our guide below which covers practical tips and support for people undergoing cancer treatment.

You can also download a PDF version of this patient information by following the link on the right.

This information will give you ways to help manage common nutritional problems often associated with cancer. These problems may relate to cancer itself or to the side effects of a specific treatment.

Practical tips and ideas will help you overcopme any nutritional problems that may happen during treatment and recovery. But trial and error is often a good approach.

Talk to your nurse or specialist doctor if you need specific dietary advice and support. They may refer you to a Macmillan Specialist Dietitian.

Why is good nutrition important?

It’s important for:

  • maintaining well-being
  • improving your body’s ability to fight infection
  • coping better with some of the side effects of treatment
  • maintaining a healthy weight or regaining lost weight.

The common forms of treatment for cancer include:

  • surgery
  • radiotherapy
  • systemic anti- cancer therapy (SACT) (includes chemotherapy, immunotherapy and targeted therapies).

The nutritional side effects you may get from cancer treatment will vary depending on the type of treatment you have. You may not experience all of these side effects, and they may come and go at different stages of your cancer journey.

What are the common nutritional side effects of cancer treatment?


Altered food intake may be because of:

  • fasting for surgery
  • decreased intake after surgery.


Problems relate to the area being treated. In the head and neck region this includes:

  • sore throat or mouth
  • dry or coated mouth
  • altered taste.

In the abdomen or pelvis this includes:

  • nausea
  • change of bowel habit.


Common problems include:

  • nausea and vomiting
  • sore mouth
  • diarrhoea and / or constipation
  • altered taste
  • loss of appetite.

What are the common nutritional problems and cancer?


We don’t really know why cancer and its treatment causes fatigue. But it can feel worse if your body doesn’t get enough food. Or if there are changes to the way your body uses the nutrients contained in food.

This can happen because:

  • you do not feel like eating
  • your body needs more energy than before
  • your body may not be able to absorb and use all the nutrients from food.

What can I do?

You can:

  • plan ahead, pace yourself and listen to your body to help manage fatigue and prevent any unintentional weight loss
  • accept offers of help with food shopping and cooking from friends and relatives.

There may be times of the day when you feel more like eating. Take advantage of this by eating well at these times.

What can I eat?

If you don’t feel able to prepare a meal, keep a range of ready meals, convenience foods and snacks in your cupboard / freezer.

Drinking a nourishing drink may be easier than eating a meal.

Our ‘eating well with a small appetite‘ patient leaflet has some recipe ideas.

Poor appetite

This is a frequent side effect of cancer and treatment. You may not feel hungry, but your body still needs nourishment.

What can I do?

You can:

  • try to keep a regular meal pattern
  • have small, frequent meals and snacks every 2 to 3 hours during the day instead of 3 meals a day
  • avoid filling up too much on fluid before a meal
  • take a short walk outside in the fresh air which may help to stimulate your appetite before a meal.
  • make the most of times when you do feel hungry and keep convenient snacks to hand.

What can I eat?

If you’re losing weight, try to include more sources of protein and calories (energy) in your diet. Good sources of protein and calories include:

  • meat
  • fish
  • milk and dairy products
  • eggs
  • pulses (peas, beans, lentils)
  • nuts.

Fortifying foods is a good way to get extra calories (energy) into your diet without necessarily having to eat more food. Add butter, cream, cheese, or oil when preparing meals.

Drinking a nourishing drink may be easier than eating a meal.

Our ‘eating well with a small appetite‘ patient leaflet includes practical advice and recipe ideas.

Feeling sick

Sometimes chemotherapy and radiotherapy treatment can make you feel sick. It’s usually temporary, but it may make eating difficult.

What can I do?

You can

  • try anti-sickness medications (antiemetics). Ask your doctor or nurse which one would be suitable for you
  • avoid eating directly before treatment if this makes the nausea worse
  • try to avoid strong smells which may make nausea worse. Ask someone else to do the cooking where possible if cooking smells make you feel sick
  • get some fresh air before eating or sit by an open window
  • avoid going for long periods without food – you may find that nibbling frequently on snacks or light meals helps to keep the sickness under control
  • avoid wearing tight fitting clothes, eat slowly in an upright position and don’t lie down immediately afterwards.

What can I eat?

You should:

  • avoid cooking smells – cold foods usually smell less than hot foods
  • avoid foods that may make you feel worse, for example greasy / fried foods, foods with a strong smell
  • try salty foods (crisps, crackers or savoury biscuits) or bland foods (chicken, toast, plain cake or biscuits)
  • try ginger flavoured food or drinks to reduce feelings of sickness (for example ginger ale, ginger biscuits, ginger tea)
  • try sucking on mints or boiled sweets.

If you’re being sick you should:

  • drink plenty of water
  • try cold, clear fluids (for example, squash, fruit juice) and aim for 10 to 12 drinks each day to replace lost fluids
  • sip drinks through a straw which you may find easier
  • include nourishing milky drinks and soups as the sickness settles, gradually moving on to light meals and snacks again.

Swallowing difficulties

This may occur if you are having radiotherapy to the mouth and throat area.

What can I do?

You can:

  • maintain good oral hygiene with a soft toothbrush
  • keep your mouth clean with regular alcohol-free mouthwashes
  • avoid extreme temperatures, for example very hot or cold foods or drinks.

What can I eat or drink?

Concentrate on soft, moist foods. Savoury foods include:

  • creamy soups
  • tender stews
  • casseroles or tagines of meat chicken
  • Quorn or tofu
  • cottage pie with extra gravy
  • fish with extra sauce

Sweet foods include:

  • milky puddings or jellies
  • sponge pudding with custard
  • mousses
  • crème caramel
  • porridge or other soft cereals.

Drink plenty of nourishing drinks between meals.

If you can only swallow liquids, ask for a referral to the Macmillan Specialist Dietitian.

Dry mouth

This can happen as a result from radiotherapy to the head or neck area, or from chemotherapy as saliva may reduce or become thicker. When your mouth is dry you’re at increased risk of getting infections such as oral (mouth) thrush and tooth decay which makes eating more difficult.

What can I do?

Ask your doctor or nurse about mouthwashes and medication that may reduce the chance of you getting oral (mouth) thrush. Artificial saliva and pastilles may provide relief for a dry mouth.

For more information see our ‘mouth care for patients undergoing cancer treatment‘ patient leaflet.

What can I eat or drink?

You can:

  • sip cool drinks frequently to help moisten your mouth
  • drink fizzy drinks to make your mouth feel fresher
  • suck ice cubes, ice lollies, or boiled
  • eat pineapple chunks which can often be refreshing and can increase saliva

You should:

  • choose soft, moist foods that have extra sauces, gravy, custard or syrup added to them
  • avoid sticky, chewy and dry foods such as bread, cold meat and chocolate that may make symptoms worse.

Sore mouth

Chemotherapy and radiotherapy can cause a sore mouth or throat. Infections, for example oral thrush, and problems with your teeth or denture can make this problem worse.

What can I do?

Maintain good mouth hygiene. Speak to your doctor or nurse who can prescribe medication to alleviate symptoms of a sore mouth.

For more information see our ‘mouth care for patients undergoing cancer treatment‘ patient leaflet.

What can I eat and drink?

You should:

  • choose soft, moist foods that have extra sauces, gravy, custard or syrup
  • drink plenty of nourishing drinks (see our eating well with a small appetite patient leaflet for recipe ideas)

You should avoid things that may irritate a sore mouth including:

  • anything salty or spicy
  • acid fruits and juices including orange, grapefruit, lemon, lime, tomato and also vinegar
  • coarse or dry foods such as crisps, toast and dry biscuits
  • alcohol, specifically wine and spirits
  • drinks that are very hot or cold. Try warm or cool drinks.

Taste changes

This could be due to treatment, medication or the cancer itself. If you have a dry mouth this may cause taste changes as well.

Some common complaints include:

  • all food tastes the same
  • food is like cardboard
  • food has a metallic taste
  • I no longer like the taste of my favourite food.

What can I do?

Keep your mouth fresh and clean with good mouthcare and drink plenty of fluids. Ask your doctor or nurse specialist about mouth care, especially if your mouth feels coated or your saliva seems thicker than normal.

For more information see our ‘mouth care for patients undergoing cancer treatment‘ patient leaflet.

If food / drinks taste unpleasant

You could:

  • replace tea or coffee with fruit squash or hot Bovril, Oxo or Marmite
  • drink more fluids, for example lemon tea, lemonade, fruit juice, ginger ale to remove unpleasant tastes
  • try using a straw and position it at the back of the mouth to bypass the taste buds
  • use herbs, spices, tomato sauce, brown sauce or chutney to  disguise unpleasant tastes. Be careful with too many spices if your mouth is sore.

If you have a metallic taste in your mouth, try sucking on mints or chewing sugar-free chewing gum, eating salty food or using plastic cutlery.

If unpleasant taste changes persist for several months

Concentrate on the foods you can enjoy the most, even if they’re different from your usual favourite dishes. Present food nicely so that you can still enjoy the look and smell of your meals.

If you’re avoiding a lot of foods and are struggling to maintain a healthy weight, ask to see a Macmillan Specialist Dietitian for advice.

If everything tastes bland

You should try:

  • putting different temperature foods together, for example fruit crumble and ice cream
  • putting different textures together, for example cottage pie and crisps or yoghurt with granola
  • blander protein sources if red meat tastse bland, for example fish, chicken, turkey, eggs or dairy products (milk, cheese, yoghurt). Pulses (peas, beans and lentils) can also be useful
  • sharp and strong flavours, for example, bitter jams, strong cheeses
  • salty foods for example, crisps, bacon, ham and crackers
  • adding meat extracts such as Oxo, Bovril or Marmite to meat dishes for extra taste (be careful if your mouth is sore).

We also suggest that:

  • sharp flavoured or fizzy drinks may stimulate your taste buds
  • fresh fruit and boiled sweets can be refreshing.

Trial and error may be the answer, keep trying. Go along with your food cravings and enjoy the foods you can manage.

Feeling full too quickly

It’s quite common to feel full even after small amounts of food and this can be very uncomfortable.

What can I do?

There are medicines that can help your stomach empty faster – ask your doctor or nurse if they would be suitable for you. Try to avoid getting constipated as this can make your symptoms worse.

What can I eat?

You should:

  • graze on small, frequent snacks and drinks rather than attempting large
  • some people find it helpful to leave a gap between their main course and pudding
  • choose high calorie (energy) foods or fortify your food with added butter, cream, cheese or oil when preparing meals
  • take liquids between meals and avoid drinking too much fluid before you eat as this will make you feel full more quickly
  • try to relax when eating, eat slowly and chew foods
  • sit up straight at mealtimes and avoid wearing tight.

You should also avoid lying down straight after eating. You may find a short walk after a meal may help you feel more comfortable.

Trapped wind can make you feel very full and bloated. Try to avoid fizzy drinks, cabbage, onions, pickles and any other items you know make your symptoms worse. Some people find peppermint tea or cordial is helpful for clearing trapped wind.


Diarrhoea can be due to a number of different factors including treatment, medications or anxiety. Whatever the cause of diarrhoea, a temporary change in diet may help alleviate symptoms.

What can I do?

Talk to your doctor or nurse about the likely cause of your diarrhoea and whether medication might help.

What can I eat and drink?

Eat little and often. Drink plenty of fluids to prevent dehydration. Aim for 10 to 12 glasses of fluid per day – remember milk, milkshakes, fruit juice, soups, custard and jelly all count, as well as water. Limit alcohol, strong tea and coffee.

It may help to cut down your fibre intake by replacing wholemeal bread and cereals with white varieties. Avoid fruit and vegetables with skins, pips and seeds while you have diarrhoea and build the fibre back up slowly into your diet as your symptoms improve.

Sometimes diarrhoea can cause temporary lactose intolerance. You may find it helpful to change to calcium-fortified soya milk or low lactose milk until diarrhoea resolves.


This may be because of cancer, treatment or medication (especially painkillers). If you’re very constipated you may feel full and suffer from nausea or sickness.

What can I do?

Talk to your doctor or nurse about suitable laxative medication.

What can I eat and drink?

Drink plenty of fluids, at least 10 to 12 glasses of fluid each day. Remember milk, milkshakes, fruit juice, soups, custard and jelly all count, as well as water.

Try to take some gentle exercise which may help alleviate constipation.

The advice for constipation is often to increase your intake of dietary fibre, although this may not have the desired effect if your constipation is not diet. Speak to your doctor or nurse to see if increasing the fibre in your diet will be of any benefit.

Should I take a vitamin and mineral supplement?

If you’re struggling with a poor appetite or reduced food intake, you may not be getting all the nutrients you need. Your diet and may benefit from taking a multivitamin and mineral supplement.

Choose a product that has approximately 100% reference nutrient intake (RNI) for all nutrients. Suitable options include Sanatogen, Superdrug, Boots or supermarket own brand A-Z multivitamin and mineral supplements. If you struggle to take whole tablets, try a chewable option for example, Centrum Fruity Chewables or Superdrug chewable A-Z.

We don’t recommend high dose vitamin and mineral supplements as they may interact with your cancer treatment. If you have any questions about other supplements or food additives, talk to your health care professional.

Vitamin D

It’s difficult to get enough vitamin D from diet alone. The main source of the vitamin is skin exposure to sunlight.

All adults should consider taking 10 mcg per day during the winter months. Some ‘at risk’ groups should consider taking a daily supplement of 10 mcg /day all year round. This includes people over 65, and those who cover their skin when outside.

Is it safe to take probiotics?

The beneficial bacteria found in certain food products or supplements may benefit your health by improving the types of bacteria in your gut (bowel). But if your immune system isn’t working properly or you’re having chemotherapy, you shouldn’t take them until 14 days after finishing your treatment.

There isn’t enough evidence to support taking probiotics during immunotherapy treatment.

Should I follow an alternative diet for treating my cancer?

There are several alternative diets claiming to treat or cure cancer. Some of these diets recommend avoiding certain foods or taking large doses of vitamins and minerals.

There’s no scientific evidence that these diets can make the cancer shrink, cure the disease or reduce recurrence. These diets are potentially harmful because they’re often low in calories and protein, and tend to be high in fibre making them very filling.

They can cause weight loss and potentially serious nutritional deficiencies in people who already have problems eating due to their cancer treatment. If you’re thinking of following an alternative diet, talk to your consultant, nurse specialist or specialist dietitian.
If you have ongoing problems with a poor appetite and unintentional weight loss, ask your doctor or nurse for a referral to the Macmillan Specialist Dietitians.

Useful resources

Watch this video about managing taste changes during cancer treatment

Watch the videos from Royal Surrey NHS Foundation Trust about diet and cancer

Free prescriptions

All cancer patients undergoing treatment for cancer, the effects of cancer or the effects of cancer treatment can apply for an exemption certificate for a free prescription from their GP.

How can I help reduce healthcare associated infections?

Infection prevention and control is important to the wellbeing of our patients so we have procedures in place. Keeping your hands clean is an effective way of preventing the spread of infections.

You, and anyone visiting you, must use the hand sanitiser available at the entrance to every ward before coming in and after you leave. You may need to wash your hands at the sink using soap and water. Hand sanitisers are not suitable for dealing with patients who have symptoms of diarrhoea.

More help or advice

Contact our patient advice and liaison service (PALS) on 01296 316042 or


About our patient information

We aim to make the information as up to date and accurate as possible, but please note that it’s subject to change. You must always check specific advice on any concerns you may have with your doctor.