Cancer Centre

Chemotherapy nurse talking to a patient


All of the questions on these pages have been asked by patients attending our weekly dietitian information sessions at the Cancer Centre. Please click on the links within the text to find out more information.

If you have a question that is not answered here, or you want to know more about how to eat well during cancer treatment, please email the dietitians on

There is so much information online on diets and cancer. I am now very confused as to what I should be eating. Who should I believe?

Anybody can start a website on the internet and this has led to many unqualified people giving nutrition advice that is not scientifically proven. There are often articles written in the press in which research is reported ‘out of context’ or based on very small studies which are carried out in laboratories or on animals. The results are often translated into headline news and give false hope that certain foods may ‘cure’ their cancer.

It is very good to have ‘hope’ but unfortunately many of these alternative diets may prove harmful to some people during cancer treatment. The best advice can be obtained from reputable sources:

What sort of diet do I need to follow if I have lost weight?

The first goal is to stop losing any more weight. This will help you to be well enough to continue with your treatment and prevent delays. Keeping a stable weight can also improve your quality of life and ensure that you are able to live as normally as possible.

You  will  need  to  relax  traditional  healthy  eating and  follow  a  high  protein,  high  energy  diet.1 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
  2. Fortify your food
  3. Eat regular snacks and puddings
  4. Drink nourishing fluids

If you are experiencing symptoms and side effects that are affecting your appetite you may need medication to help. For example if you are feeling sick, or your bowels are not working properly, you will feel less like eating. Medications can help, so speak to your oncologist or specialist nurse for more advice.

How do I gain weight?

Gaining weight during cancer treatment can be difficult, but not impossible if you eat well. Try not to put too much pressure on yourself to gain weight. The most important thing is to prevent weight loss. You may find it is easier to put weight back on once your treatment is finished.

In order to maintain or gain weight you will need to relax healthy eating principles and use some building up suggestions. Make sure you are including snacks and puddings every day, especially if your main meals have become smaller. Use higher fat foods such as whole milk and cheese.

What should I eat if I have lost muscle and strength?

It is common to lose muscle after a cancer diagnosis. This can affect your quality of life and make you feel weaker than normal. You might find simple tasks like walking up the stairs, hoovering or taking a short walk much harder than before.

You will also need to make sure you are eating enough protein to keep your strength up. This will help you to stop losing more muscle. People with cancer usually need more protein than the healthy population. Your requirements are calculated with your weight in kilograms. You are advised to eat 1-1.5g per kg per day1.

How can I eat enough protein?

Protein is found in meat, fish, eggs, beans, pulses, nuts and dairy foods. Try to include some sort of protein in each meal. You might find some foods easier to eat and drink, for example full fat (or gold top!) milk, cheese, custard or full fat yoghurt.

Doing some physical activity can help boost appetite and keep your muscles strong. Try starting with a short walk around the block or you can read Macmillan’s Move More booklet for other tips here.

Is it safe to drink alcohol after a cancer diagnosis and during treatment?

Alcohol has been linked to an increased risk of 7 different cancers including breast, mouth and bowel cancer and drinking too much alcohol is estimated to cause 3% of all cancers in the UK2. It is therefore important to reduce alcohol intake at the end of treatment to reduce your risk of recurrence or developing another cancer. 

It is usually safe to have the occasional alcoholic drink during cancer treatment but it is always worth discussing this with your oncologist. Some medications can react with alcohol so read the patient information to be sure.

Current recommendations from the UK Chief Medical officer state that men and women should limit alcohol intake to 14 units per week, spread over 3 days or more. Go to the drink aware website here for more information on units of alcohol and reducing your intake.

I have finished my cancer treatment and am keen to be as healthy as possible. What diet should I follow?

Food is important to support you through and after your treatment, and lifestyle changes may reduce the risk of your cancer coming back. If you are well, have not lost weight and have no ongoing symptoms from your treatment, you are advised to follow a healthy balanced diet. It is also important to be a healthy weight, since being overweight may increase your risk of certain cancers.

A healthy balanced diet is based on the Eatwell Guide - which you can read here - and should include a selection of foods from each of the following food groups:

  • Fruit and vegetables.
  • Starchy foods, 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.

What is a healthy weight?

A healthy weight is based on the ratio between your weight and height. This is known as your Body Mass Index (BMI). You can use the NHS height/weight chart here to see if you are in the healthy range.

Always remember that if you are having cancer treatment we do not recommend that you lose a lot of weight. It is better to wait until your treatment is finished when adopting a healthy lifestyle will reduce your risk of recurrence.

What should I eat to stop my cancer coming back?

The advice on diet after cancer treatment is the same as the advice for all cancer prevention. The World Cancer Research Fund has researched all possible lifestyle risks and has set out a set of recommendations as follows: 

  • Be a healthy weight.
  • Move more.
  • Eat more grains, vegetables, fruit and beans.
  • Avoid high calorie foods.
  • Limit red meat and processed meats.
  • Limit sugar sweetened drinks.
  • Do not drink alcohol.
  • Do not rely on vitamin and mineral supplements.

Does sugar feed cancer?

There are many websites and books that suggest that sugar can ‘feed’ cancer or encourage the tumour to grow.  Cancer cells, and all the other cells in our body, use sugar in the form of glucose as a source of energy. There is a theory that if we remove all sugar from our diet, the cancer cells will ‘starve’ and then die.

There is however no evidence to suggest that the sugar in foods that we eat directly results in the growth of cancer cells. Nor is there anything to suggest that stopping all sugar in our diet will lead to the ‘death’ of cancer cells. .

The work of scientists has shown that the process is much more complex and involves a number of genetic factors as well.

Sugar does not contain any useful nutrients apart from providing us with energy and can lead to unnecessary weight gain. It is better to get our energy from healthier food options. If you are coping well with your treatment it is recommended that you eat a healthy diet which means that you should cut back on the amount of sugary snacks and drinks that you eat.

There is strong evidence to show that being overweight may increase your risk of cancer recurrence. Eating a diet high in sugar can lead to excess weight gain. The most recent recommendation is to limit sugar in the diet to less than 5% of all your intake4. This is the same as 25-30g per day of sugar.  If you have finished treatment and are overweight, it is therefore advisable to limit foods and drinks with added sugar and focus on a healthy balanced diet. This will lower your calorie intake and encourage weight loss, and help reduce the risk of your cancer coming back.

If you want to read more about the relationship between sugar and cancer there is more detailed information on the Cancer Research website here.

Should I follow a ketogenic diet?

A ketogenic diet is a very low carbohydrate diet that is made up of 75% fat, 20% protein and 5% carbohydrates. This is very different from a healthy balanced diet that is made up of 30% fat, 15% protein and 55% carbohydrates.

A ketogenic diet is used commonly with children diagnosed with epilepsy and who do not respond to medication.

There has been a lot of speculation in the press about the benefits of a ketogenic diet to cure cancer. The theory is that by restricting carbohydrates, the usual process of cell growth is interrupted and cancer cells respond better to treatment and are less inclined to multiply and spread.

A recent review of the evidence has not shown any benefits for cancer patients. There have been several clinical trials, all with small numbers of patients, using different cancers, different treatments, looking at different outcomes and some feeding patients through a vein. As a result the conclusions are very varied and cannot be compared, or used as evidence in a clinical setting5 6.

The ketogenic diet is very hard to follow, and it requires specialist help from a qualified healthcare professional. We do not advise that anyone with a cancer diagnosis tries this since we do not have proof that it will be beneficial.

Are there any foods I should avoid during cancer treatment?

There are no foods that you need to totally avoid during cancer treatment. There is a lot of information on the internet about diet restrictions, but most has not been tested in studies and since there is not evidence it is not necessary to cut them out of your diet.

The only time that it is necessary to avoid certain foods is if you have been diagnosed with a food allergy or intolerance e.g. coeliac disease. If you think that you have a problem then speak to your doctor or specialist nurse and ask to be referred to a dietitian.

If you are eating well and not lost weight it is best to follow a healthy balanced diet. If you have a poor appetite and have lost weight, you should follow a high protein, energy diet. 

In some cases your doctor or dietitian may recommend that you do not eat certain foods. This usually depends on the stage of your cancer or your symptoms.

Do I need to cut bread and carbohydrates out of my diet?

Bread and other carbohydrate foods are an important part of a healthy balanced diet. Carbohydrates are a source of fuel and provide us with energy. They also contain fibre, vitamins and minerals.

We recommend that you eat a small portion of carbohydrate (bread, potato, rice, pasta, couscous or cereals) at each meal. Wholegrain varieties such as granary bread, brown rice or pasta are the best options.

Carbohydrates should make up about one third of your overall diet.

Do I need to follow a wheat or gluten free diet?

You only need to cut out wheat or gluten out of your diet if you have been diagnosed with coeliac disease or a wheat or gluten intolerance. There is no scientific evidence to show that restricting these foods unnecessarily will cure your cancer.

Do I need to avoid dairy?

To date, no evidence exists to support any harm from milk and dairy produce when taken in moderate amounts and as part of a healthy diet and lifestyle.  Milk is a good source of protein and contains a wide range of important vitamins.  It is also a rich source of calcium, important for healthy bones, muscle function and blood clotting.

Research does not support a relationship between milk, or milk products, and cancers of the breast, lung, stomach or pancreas.  In fact milk, particularly whole milk, has been shown to protect against certain cancers, reducing the risk of bowel cancer7 8 9. There is limited evidence to suggest that dairy foods could increase the risk of prostate cancer, but since no harm has been proven, there are currently no recommendations to remove it from the diet.

It is therefore safe to include dairy and milk products in your diet. If you still want to follow a dairy free diet it is important to make sure that you are eating other calcium rich foods. These include tinned fish e.g. sardines or salmon or green leafy vegetables. Always choose milk alternatives that are fortified with calcium.

Do I need to avoid red meat?

No. The World Cancer Research Fund has recommended that excessive red and processed meats should be avoided to reduce the risk of cancer recurrence. However you can still enjoy up to 500g of lean red meat each week. Red meat is a good source of protein, iron and other minerals and is safe to eat as part of a balanced diet.

Can I eat dried fruit?

Yes you can. A portion of dried fruit is one heaped tablespoon and counts towards your recommended 5-a-day. Fresh, frozen and tinned fruit and vegetables are also good options.

Can I drink coffee?

Yes. You can enjoy coffee every day if you want to. There is no evidence to say that coffee increases the risk of cancer, and in fact it may actually reduce the risk of cancer, but this has yet to be proven.

You may find that you do not like the taste of coffee during your cancer treatment. It is important to make sure you are drinking enough, so if you ‘go off’ coffee, make sure that you are drinking something else instead to stop you getting dehydrated.

If you are losing weight and are still enjoying your coffee, choose a cappuccino, latte or milky coffee made with whole milk. This is an easy way of having more calories without eating a big plateful of food.

Should I eat organic food?

Organic food is described as “food grown without most artificial fertilisers or pesticides, making the most of natural fertilisers. Animals are kept in ways which minimise the need for medicines and other chemical treatments.” (DEFRA)

People are sometimes concerned about the possible effects of food additives on health, including cancer, and feel that organic foods are less likely to be contaminated with pesticides.

There is evidence to suggest that eating an organic diet does not reduce the risk of developing cancer6. There have been studies which have looked at the nutrient content of organic versus conventionally grown fruit and vegetables. Some studies suggest a higher nutrient content, others suggest no difference.

Vegetables, fruits and whole grains should form the central part of your diet regardless of whether they are grown conventionally or organically. Most experts agree that the nutritional benefits of eating fruits and vegetables outweigh the risk of consuming chemical residue on non-organically grown produce.

Cancer Research UK says ‘Fruit and vegetables sometimes contain very small amounts of pesticides so it is a good idea to rinse fruit and vegetables before eating them. But there is no evidence that these small amounts increase the risk of cancer in people who eat them. In fact, eating lots of fruit and vegetables actually reduces your risk of several cancers, despite any pesticide residues on them.’

Do eggs bind you up?

There is no evidence that eggs can bind you up. However people who eat a lot of eggs may not eat enough fibre (fruit, vegetables, wholegrains) and so can become more constipated.

Eggs are high in protein and rich in vitamins, and can be eaten as part of a healthy diet.

If you are losing weight during treatment and cannot face your main meal, boiled poached or scrambled eggs can be a useful alternative and you may find them easier to eat than ‘meat and 2 veg’.

Will eating eggs push up my cholesterol?

Eggs contain dietary cholesterol but this does not push up blood cholesterol levels. Saturated (animal) fats are the main food type that increase blood cholesterol, therefore if you have high cholesterol you should try to cut back on saturated fat instead. Use vegetable based spreads and oils (e.g. olive and sunflower), trim fat off meat and use lower fat dairy products (e.g. semi skimmed, 1% or skimmed milk).

Which oil should I use in cooking?

Choosing which fats and oils to use can be daunting since there are so many to choose from.  For a healthy balanced diet, it is best to use vegetable oils and spreads as much as possible e.g. olive, rapeseed and sunflower oil. These are a healthier option to butter and are less likely to push up your cholesterol.

If you need to lose weight, try to limit fats and oils as much as possible since these are very energy dense and contain a lot of calories.

Is margarine bad for you?

No. It is perfectly safe to eat margarine and low fat spreads. If you are following a healthy balanced diet they are a better option than butter or other animal fats since they contain vegetable oils (e.g. sunflower or olive). If you choose butter it is more likely to increase your cholesterol.

Butter and spreads have the same calories and so there is no need to swap to butter if you are losing weight. Just make sure that you are not using the low fat spreads since these will not provide as much energy as the ‘full fat’ options.

Should I avoid eating butter?

Yes, most of us should. Butter is a saturated (animal) fat and can lead to raised cholesterol. If you are following a healthy diet it is better to choose a vegetable based spread and limit the use of butter as much as possible.

If you have lost weight or are losing weight during your treatment, it is safe for you to increase the fat in your diet. Butter contains the same amount of energy as vegetable oils so it is not necessary to start using it instead. However if you find butter easier to eat, it is a good option. Once your treatment is finished and you are eating normally again, you should go back to a more healthy vegetable based option.

Should I include coconut oil and coconut milk in my diet?

Coconut oil has been reported in the press to have health benefits, including the claim that it will cure cancer. Many of these have not been proven and there is no evidence to suggest that it will cure cancer.

Coconut oil behaves like saturated fat and therefore is not recommended as your main source of fat in cooking as part of a healthy diet. Healthier choices would be vegetable based oils e.g. olive, rapeseed and sunflower oil.

It is safe to use other coconut products like desiccated coconut and coconut milk, but use them in moderation if you are trying to lose weight.

If you are struggling with poor appetite during your treatment or losing weight, coconut milk in sauces and curries is a better option than lower fat tomato based options.

Can I cook using ghee?

Ghee is high in saturated (animal) fat and therefore can increase your blood cholesterol levels. It is best avoided if you are following a healthy diet. A better choice would be olive, sunflower or other vegetable based oils.

If you are losing weight, it is advised to increase the fat in your diet. You can use ghee to fortify curries and sauces. This will make them richer and help stop you losing weight.

Can I use Udo's oil or another omega 3 supplement during cancer treatment?

Omega 3 is a fat that is naturally found in oily fish (salmon, trout, sardines, mackerel, herring). Eating oily fish and vegetarian sources of omega 3, such as nuts and seeds, on a regular basis has been shown to reduce the risk of heart disease as part of a healthy diet10.

A lot of research has been carried out to determine if taking omega 3 fats are beneficial in the treatment of cancer. Some studies have shown slight improvements on appetite, weight, quality of life and muscle mass11 12 13. Some trials have demonstrated that omega 3 supplements could improve response to anti-cancer treatment and survival. However others have not shown any benefit14 15 16. All of the research to date has been conducted on small numbers of patients and with different doses of omega 3. There are reports of omega 3 reducing the side effects of some chemotherapy agents used with advanced breast cancer17 and lung cancer18. Yet another trial has not shown benefit in lung cancer19.

In spite of the lack of consensus, there is a weak recommendation for the use of omega 3 supplements in advanced cancer to improve appetite and weight1.

It is usually not advised to take vitamin, mineral and other over the counter supplements since they may react with your cancer treatment. Omega 3 supplements may be safe, but it is always important to talk to your oncologist or pharmacist at your cancer centre.

Should I take a vitamin and mineral supplement?

For most people, a balanced diet will provide all the nutrients that you need, and taking large doses of vitamins, minerals and other dietary supplements is not necessary or recommended1.

It is important to remember that some of the vitamins and minerals can be harmful when taken in high doses and can react with some medications. There is currently no strong evidence that dietary supplements can help to treat or control the growth of cancer.

If you find it difficult to eat a balanced diet you may benefit from taking an A-Z multivitamin and mineral supplement containing up to 100% of the recommended daily allowance (RDA) Sanatogen A-Z and Tesco Multivitamin and Mineral Supplement are suitable choices1 20.

It is important to inform your doctor, specialist nurse or dietitian before you start any dietary supplements to confirm that they are safe for you to take.

Do I need to take a Vitamin D supplement?

We make most of our Vitamin D in our skin from exposure to the sun. Small amounts can also be provided from food sources including:

  • Oily fish e.g. salmon, sardines, mackerel
  • Egg yolks
  • Offal
  • Margarines and spread fortified with Vitamin D

Vitamin D helps us to absorb calcium in the gut, and supplements for calcium and vitamin D are often sold together.

Many cancer patients have been shown to be deficient in Vitamin D21.  If your doctor has tested you and you are found to be deficient you will be asked to take a supplement.

It is now recommended that everyone in the UK takes a Vitamin D supplement (10mcg per day) during the winter months from October to April22.

The following groups of people are more at risk of vitamin D deficiency and should take a supplement all year round:

  • Anyone over the age of 65
  • Women who are pregnant or breastfeeding
  • Anyone who covers most of their skin when they are outdoors
  • Those with darker skin tones living in the northern hemisphere
  • Those living in institutions such as residential care homes.

You can read more about Vitamin D here.

Please check with your doctor, specialist nurse or dietitian before taking a Vitamin D supplement in excess of 10mcg per day.

Does skimmed or semi skimmed milk have more calcium?

There is the same amount of calcium in whole, semi-skimmed, 1% and skimmed milk. You can read a booklet from the Dairy Council with facts about the properties and benefits of drinking milk here.

How much calcium do I need?

Calcium requirements depend on your age and gender. Adults over the age of 18 need 700mg per day, but women past the menopause need 1250mg per day. Foods rich in calcium include dairy products, tinned fish (with bones), green leafy vegetables and white bread. 


2 Cancer Research UK: Alcohol facts and figures Accessed online 19/8/2018

3 Scientific Advisory Board on Nutrition (SACN). Carbohydrates and Health. 2015. TSO, London.  Accessed online 28/8/2018.

4 Oliveira CLP, Mattingly S, Schirrmacher R et al. (2018) A Nutritional Perspective of Ketogenic Diet in Cancer: A Narrative Review. Journal of the Academy of Nutrition and Dietetics 118(4):668-688.

5 Sremanakova J, Sowerbutts AM, Burden S (2018) A systematic review of the use of ketogenic diets in adult patients with cancer. Journal of Human Nutrition and Dietetics. Jul 30. doi: 10.1111/jhn.12587. [Epub ahead of print] Accessed online 28/8/2018.

6 Bradbury, KE, Balkwill A, Spencer EA et al. (2014) Organic food consumption and the incidence of cancer in a large prospective study of women in the UK. British Journal of Cancer 110(9):2321-6.

7 World Cancer Research Fund and American Institute of Cancer Research (2018) Diet, Nutrition, Physical Activity and Cancer: A Global Perspective. Accessed online 19/8/2018.

8 Aune D, Lau R, Chan DS et al. (2002) Dairy products and colorectal cancer risk: a systematic review and meta-analysis of cohort studies. Annals of Oncology 23(1) 39-45.

9 Viera AR, Abar L, Chan DSM (2017) Foods and beverages and colorectal cancer risk: a systematic review and meta-analysis of cohort studies, an update of the evidence of the WCRF-AICR Continuous Update Project. Annals of Oncology 28(8):1788-1802.

10 del Gobbo LC, Imamura F, Aslibekyan S et al. (2016) Omega-3 Polyunsaturated Fatty Acid Biomarkers and Coronary Heart Disease: Pooling Project of 19 Cohort Studies. JAMA Internal Medicine 176(8):1155-66.

11 Moses AW, Slater C, Preston T et al. (2004) Reduced total energy expenditure and physical activity in cachectic patients with pancreatic cancer can be modulated by an energy and protein dense oral supplement enriched with N-3 fatty acids. British Journal of Cancer 90: 996-1002.

12 Silva J, de A, Trindade EB, Fabre ME, et al. (2012) Fish oil supplement alters markers of inflammatory and nutritional status in colorectal cancer patients. Nutrition and Cancer 64: 267-73.

13 van der Meij BS, Langius JA, Spreeuwenberg MD et al. (2012) Oral nutritional supplements containing n-3 polyunsaturated fatty acids affect quality of life and functional status in lung cancer patients during multimodality treatment: an RCT. European Journal of Clinical Nutrition 66(3):399-404.

14 Bruera E, Strasser F, Palmer JL et al. (2003) Effect of fish oil on appetite and other symptoms in patients with advanced cancer and anorexia/cachexia: a double-blind, placebo-controlled study. Journal of Clinical Oncology 21:129-34.

15 Jatoi A, Rowland K, Loprinzi CL et al. (2004) North Central Cancer Treatment Group. An eicosapentaenoic acid supplement versus megestrol acetate versus both for patients with cancer-associated wasting: a North Central Cancer Treatment Group and National Cancer

Institute of Canada collaborative effort. Journal of Clinical Oncology 22:2469-76.

16 Fearon KC, Barber MD, Moses AG et al. (2006) Double-blind, placebo-controlled, randomized study of eicosapentaenoic acid diester in patients with cancer cachexia. Journal of Clinical Oncology 24:3401-7.

17 Ghoreishi Z, Esfahani A, Djazayeri A et al. (2012) Omega-3 fatty acids are protective against paclitaxel-induced peripheral neuropathy: a randomized double-blind placebo controlled trial. BMC Cancer 12:355

18 Murphy RA, Mourtzakis M, Chu QS et al. (2011) Supplementation with fish oil increases first-line chemotherapy efficacy in patients with advanced non-small cell lung cancer. Cancer 117:3774-80.

19 Sanchez-Lara K, Turcott JG, Juarez-Hernandez E et al. (2014) Effects of an oral nutritional supplement containing eicosapentaenoic acid on nutritional and clinical outcomes in patients with advanced non-small cell lung cancer: randomised trial. Clinical Nutrition 33:1017-23.

20 Norman HA, Butrum RR, Feldman E et al (2003) The role of dietary supplements during cancer therapy. The Journal of Nutrition 133(S11):S3794-9.

21 Ströhle A, Zänker K, Hahn A. (2010) Nutrition in oncology: the case of micronutrients

(review). Oncology Reports 24:815-28.

22 Scientific Advisory Board on Nutrition (SACN) (2016) SACN vitamin D and health report [online] Available at: [Accessed online 28/8/2018.