Healthy living

Following a healthy lifestyle is a priority for many women living with secondary breast cancer. However, this isn’t always straightforward.

It can be difficult to know how much physical activity is safe and achievable for you. With so many different diets and headlines relating to nutrition and cancer, you may also feel confused about what to eat and what to avoid.

This section gathers together a range of information and evidence to guide you in living well with your secondary breast cancer. Here, we cover recommendations and tips for being physically active whilst living with secondary breast cancer, as well as an overview of the evidence for different foods and diets which are often discussed in relation to cancer.

In this section

Physical activity

There is lots of research and focus on the benefits of physical activity after treatment for cancer but less so on the benefits for people living with advanced stage cancer, such as secondary breast cancer.

Recently, researchers gathered together the evidence from different studies exploring the effects of exercise in patients living with advanced stage cancer. They found the following potential benefits [1];

  • Maintenance of physical strength and functions so that patients can continue to carry out every day activities as normal
  • Maintenance of independence.
  • Better control of symptoms such as fatigue (tiredness) and pain.
  • Improvements in quality of life.

A study of women living with advanced breast cancer (i.e. stage 3 OR stage 4/metastatic/secondary) found that those who performed seated exercises (a range of exercises of the arms and legs which can be performed from a chair) had much lower fatigue than women who did not [2].

Another study looked at yoga in women with secondary breast cancer and found that, the day after performing yoga, women were more likely to experience improvements in both pain and fatigue [3].

Previous research has found further benefits of physical activity for patients living with cancer in general [4];

  • Better sleep.
  • Improved mood and mental health.
  • Less risk of falling over.
  • Improved survival.

Finding what is right for you: how much and how often?

Unfortunately, because of limited evidence, guidance and understanding, lots of women living with secondary breast cancer are nervous to exercise for fear that this could cause them harm. Information on the amount and types of exercise considered safe may not always be clear but don’t let this put you off. The benefits of exercise are overwhelmingly clear and, together with your doctor, you will be able to find an exercise regime that is right for you, whether seated exercise, group exercise classes, jogging, swimming, yoga or regular walking.  

If appropriate to their individual situation (as assessed by their medical professional), people living with cancer are advised to follow the same exercise guidelines as people are who are not living with cancer.

This involves;

  • 150 minutes of moderate exercise such as cycling or fast walking per week (this could be around 30 minutes per day) OR 75 minutes of vigorous activity such as running or tennis.
  • Two or more sessions per week of strength exercises involving the major muscles (legs, hips, back, abdomen, chest, arms and shoulders) [4].

Points to bear in mind

These are general guidelines and the amount that you can do will very much depend on your own fitness and abilities, just as it does for people who are not living with cancer.

Your doctor will be the best person to advise you on whether any aspects of your treatment, cancer diagnosis (e.g. where it has spread to and what symptoms it is causing) or other health conditions mean that you should take particular cautions or make any adjustments when performing exercise.

Remember to rest and recover between exercise. This is just as important as the exercising itself. Incorporating rest days into your exercise routine allows your body to recuperate and you to feel energised for the next session. Getting plenty of sleep is also important. If you have been struggling to sleep, you may find that increasing the amount of exercise you do has the added benefit of improving your sleep too.

Exercising when the cancer has spread to your bones

Some women feel particularly concerned about exercising if their breast cancer has spread to their bones, as they worry about breaking them or causing further pain and damage.

Spread of cancer to the bones does make them more vulnerable to breaking (this is referred to as ‘pathological fractures’). However, avoiding exercise can lead to loss of muscle strength and function which can itself increase the risk of bone pain, fractures (breaks) and falling over. This is due to what is known as ‘disuse osteoporosis’ i.e. thinning of the bones due to lack of use or exercise.

Women living with secondary breast cancer in the bones (also known as metastatic bone disease) are therefore advised to remain physically active by continuing to have regular, gentle exercise. Depending on the sites where your cancer has spread (e.g. back, hips, ribs), your doctor or physiotherapist will be able to advise you on the best form of exercise to allow you to get all the benefits of physical activity whilst reducing your risk of fracturing any of your bones by avoiding impact on certain areas.

Ask your doctor, nurse or physiotherapist for advice on developing an exercise plan that is suited to you.

Tips for getting started with exercise

Speak to your doctor or nurse first. They will be able to advise you on the amount and sorts of exercise that will be safe and appropriate for you. They may recommend courses or classes run in the hospital, by a local service or refer you to a physiotherapist or occupational therapist for further guidance. These professionals can help you to determine your current fitness level and to set realistic goals for yourself.

Take it steady. Build up the amount of exercise you do gradually over time.

Go with how you feel. Rather than trying to stick to a set routine or exercise regime, exercise when you feel well and able to. You may find that you have more energy on some days than others, or that you don’t always feel well enough to exercise, such as during or immediately after a chemotherapy cycle. Go with what feels right for your body.

Stick to what feels comfortable for you. Don’t feel like you have to push yourself outside of your comfort zone. Any exercise you do should feel enjoyable. Some good examples of gentle exercise include; walking at a steady pace, swimming, cycling and yoga. Environment is important too. Whilst some people like to exercise in a gym or group setting, others feel more comfortable at home, outside in the fresh air or one to one with an instructor or professional who is aware of their cancer and understands any limitations this might bring.


  1. Dittus KL, Gramling RE, Ades PA. Exercise interventions for individuals with advanced cancer: A systematic review. Preventive medicine. 2017 Nov 1;104:124-32.
  2. Headley JA, Ownby KK, John LD. The effect of seated exercise on fatigue and quality of life in women with advanced breast cancer. In Oncology Nursing Forum 2004 Sep 1 (Vol. 31, No. 5).
  3. Carson JW, Carson KM, Porter LS, Keefe FJ, Shaw H, Miller JM. Yoga for women with metastatic breast cancer: results from a pilot study. Journal of pain and symptom management. 2007 Mar 1;33(3):331-41.
  4. Macmillan Cancer Support. Physical activity for people with metastatic bone disease. Guidance for health professionals.

Other sources

  • Cancer Research UK exercise guidelines
  • Yee J, Davis GM, Hackett D, Beith JM, Wilcken N, Currow D, Emery J, Phillips J, Martin A, Hui R, Harrison M. Physical Activity for Symptom Management in Women With Metastatic Breast Cancer: A Randomized Feasibility Trial on Physical Activity and Breast Metastases. Journal of pain and symptom management. 2019 Jul 30.

Diet & nutrition

Eating a healthy, balanced diet is an important aspect of living well with secondary breast cancer.

Some people also look to their diet as a way of supporting their body and their treatment to fight off cancer. In this way, diets and dietary supplements can be seen as a complementary therapy.

But what is the healthiest diet to follow? With so many different diets, superfoods and supplements and so much different, and often conflicting, advice out there, it can be difficult to know what you should and shouldn’t be eating. 

The guidance

Put simply, a colourful diet of lots of fruit and vegetables which is low in fat and high in fibre is healthy and balanced. Lean meat and oily fish, protein alternatives such as lentils, beans, tofu and eggs, wholegrains such as brown bread and brown pasta and calcium-rich dairy products (or dairy alternatives) such as milk, yoghurt and cheese all provide the key nutrients the body needs to function in illness and in health.

Cancer Research UK advises thinking of foods as ‘every day foods’ i.e. fruit, vegetables, protein, wholegrain etc. which should be part of your daily diet and ‘occasional foods’ i.e. foods high in sugar, fat or salt which should be enjoyed as more of an occasional treat.

It can be hard to know what the correct portion size is for different foods and difficult to interpret from the weights on the back of packets. To help, the British Nutrition Foundation have published an online guide to portion sizes and healthy eating. This also includes lots of helpful information on nutrition in general.

Special diets & dietary supplements

Overall, health professionals and dietitians recommend that the best ‘healthy’ diet to follow is one which is well-balanced, colourful and enjoyable.

However, there are lots of other aspects of diet that you may have heard about and want to find out more.

Living with a cancer that cannot be cured, and often undergoing treatment which is causing lots of unpleasant side effects, means that some women with secondary breast cancer look to find a cure or treatment elsewhere. Lots of diets and supplements are described as having a range of health benefits for people with cancer, some even claiming to cure cancer.

There has been a rise in different types of ‘anti-cancer’ diets reported in the media and online in recent years, some intended to be an alternative to (i.e. used instead of) conventional cancer treatment. Whilst following these diets may help people to take control, to feel healthier and maybe even to feel some psychological or side-effect related benefits, there is no evidence that any diet can cause a cancer to shrink, cure cancer or give someone a greater chance of survival.

Lots of these diets can be very expensive to follow, time consuming to prepare and prevent people from getting the correct amounts of vital vitamins and nutrients by cutting out key sources and food groups. This can be harmful to health. All of this aside, these diets can also be so restrictive that they take the enjoyment out of food and eating and can make you feel guilty if (understandably) you struggle to follow strict rules and restrictions.

Other people may disagree and may find following a different diet, in discussion with their medical team or a dietitian, is helpful and positive for them.

Whilst following certain diets or taking supplements may have real health benefits for some people, it is important to be aware of the evidence and any potential risks to you and your health.

Here, we provide a summary of some of the diets and supplements which are often discussed in relation to preventing, treating or managing cancer and, where available, discuss the evidence to allow you to make informed and safe choices about your diet.

Whatever you decide, it is important that you let your medical team know of any changes or additions to your diet to be sure that these will not interfere with your treatment or have a negative impact on your health.

Cancer & antioxidants

Vitamin A, vitamin C, vitamin E, selenium and coenzyme Q10 are all antioxidants. These are some of the most commonly taken dietary supplements.

A chemical reaction called ‘oxidation’ happens when the body performs all sorts of essential functions such as breaking down food to release energy, building new cells and making hormones. These oxidation reactions release chemicals called ‘free radicals’ which can cause damage to surrounding cells. Antioxidants absorbed from our diet act to hoover up these free radicals and protect our cells from damage, which could otherwise lead to cancer.

Tomatoes and other fruits and vegetables are a natural source of vitamins A, E and C, as well as other important nutrients.

Some people choose to take extra antioxidants as supplements to ‘boost’ cell protection.

However, the relationship between antioxidants and cancer development is complex, and one that we do not yet fully understand. Whilst some scientific research has shown that antioxidants do indeed protect cells from damage, other studies suggest that they are not always protective and there is evidence to suggest that taking antioxidant supplements may interfere with cancer treatment and prevent it from being as effective as it can be.

Whilst there is some promising research, it is important to remember that cells grown and tested on in the laboratory by scientists do not behave the same way as cells in the body. Much more research in humans is now needed for us to fully understand the relationship between cancer and antioxidants and how we can make the most of this in cancer treatment.

Cancer Research UK have a scientific blog series which has covered the topic of antioxidants and cancer.

If you do decide to take antioxidant or any other supplements, or if you are already taking a supplement, it is important to let your doctor (or, if you have one, your breast cancer nurse) know so that they can discuss any potential risks with you.


Cancer & sugar

The role of sugar in the development of cancer is another very important topic and one which has been covered a lot in the media, causing much concern amongst cancer patients and the general public. There are a number of myths or untruths surrounding this.

Sugar comes in lots of different forms, from lots of different types of food.

When we talk about sugar in relation to diet, we are most often talking about table sugar or ‘sucrose’, the type of sugar that we add to tea and coffee and that is found in fizzy drinks, cakes and biscuits for its sweet taste. Sucrose is refined, which means it has been processed to extract it from its natural source. This is where the term ‘processed sugars’ comes from. Sucrose is made when glucose and fructose stick together. Think of them as single beads joining together to make a chain. As the chain gets longer, the sugar loses its sweet taste and becomes starchy. Starchy sugars are found in foods such as bread, rice, pasta and in vegetables such as potatoes.  All sugars are carbohydrates or ‘carbs’.

Lots of complex biological reactions happening in the body rely on us having a constant supply of energy. We get energy by breaking down carbohydrate sugar chains to release glucose. Our body cannot function without sugar (in its various forms); it is the fuel of life.

Cancer cells grow and multiply very quickly. They need lots of energy in the form of glucose to do so. This has led to the theory that sugar feeds cancer cells. However, this is far too simple. It is not just sugar that they need – their growth also relies on other important substances such as fats and amino acids (the building blocks of proteins) which we also get from our diet.

Furthermore, nearly ALL of the many different cells in our body require energy in the form of sugars, NOT just cancer cells. There is no way of telling our body to starve cancer cells of glucose but to continue to give it to normal cells. When we have something sugary like a biscuit or fizzy drink, glucose is quickly absorbed into our bloodstream ready to be used as energy by our cells. Cutting out these processed sugars doesn’t mean our cells won’t get glucose. When we eat starchy foods such as pasta and potatoes, our body breaks down these more complex sugars to release glucose. Even if we were to cut out all of these different forms of sugars, our body is still able to turn fats and proteins into glucose as a last resort. The body simply cannot function without glucose.

There is no evidence to support the theory that cutting out sugar will kill or starve cancer cells. Eating sugar does not directly feed cancer cells.

Whilst sugar does not directly cause cancer, it can indirectly lead to cancer. This is because, as is well known, consuming lots of sugary foods and drinks leads to weight gain and obesity. Obesity is known to be a strong risk factor for developing cancer, as evidenced by lots of research trials.

Processed sugar does not contain any useful nutrients which can be used by the body. The energy it provides can be gained from much healthier sources. So, whilst the evidence doesn’t support claims of sugar directly causing cancer, there are many benefits to cutting down the amount of sugar you consume.

There is research to suggest that cancer cells use energy differently to normal cells. Scientists are now working to better understand this, to help in the development of more effective treatments.

Cancer Research UK has a scientific blog series which has covered the topic of cancer and sugar.  


Cancer & ‘superfoods’

Lots of foods have gained the label ‘superfood’ in relation to health related properties they are reported to have.    

This has included foods such as blueberries, kale, beetroot, broccoli and green tea. Whilst most of these so called ‘superfoods’ are in fact very healthy and good to include as part of a balanced diet, there is no scientific evidence to say that they offer special health benefits above and beyond their nutritional value. Whilst isolated chemicals, such as antioxidants from blueberries, may have an effect on cancer cells in the laboratory, they are likely to behave very differently when eaten as a food and absorbed in the body. These studies also often use high doses of an individual chemical or compound, which we would struggle to get from eating, say, a normal amount of blueberries in our diet.

Despite a lack of evidence, the phrase ‘superfood’ has become a useful marketing term for companies to sell their products to increasingly health-conscious consumers.

Rather than increasing your intake of one particular food, there is much more health benefit to be had from eating a varied, well-balanced diet which includes lots of different fruits, vegetables and wholegrains.

Cancer Research UK provides further information on cancer and superfoods, as well as other foods frequently discussed in relation to cancer.


Cancer & turmeric

In recent years, there has been lots of focus online and in the media on the potential health properties of turmeric.

Turmeric is a bright yellow spice which has been used in cooking for hundreds of years. We know that turmeric is safe to use and consume in foods. It is used it lots of Asian cooking and is the main component of curry powder.

In certain countries, where turmeric is used a lot in cooking, there are lower rates of certain cancers. However, we do not know if it is safe for use as a medicine or cancer treatment, particularly in the large amounts which would be needed to see a medicinal effect (i.e. for it to be able to treat ill health).

Lots of research, in the past and more recently, has looked into claims of its ‘super food’ and ‘cancer curing’ properties.

Certain substances in turmeric, known as curcuminoids, are known to have anti-inflammatory properties (i.e. they prevent inflammation, which is the body’s response to injury) and may prevent the cell damage which can lead to cancer. Curcumin is the main active curcuminoid found in tumeric.

In laboratory studies, curcumin has been shown to prevent cancer in animal cells. However, there is currently no clear evidence for this in humans. Research therefore does not support the use of turmeric to prevent or treat cancer. Further studies are needed.

Some websites and other non-scientific sources report that turmeric can cure cancer and some even recommend that it should replace conventional treatments, often by being taken in very large quantities. There is no scientific evidence to support these claims. Whilst turmeric used in cooking is very safe, we do not know how safe it is when consumed in very large quantities. Taking it in such large amounts can also cause a range of side-effects such as stomach pain and yellowing of the skin.

Expert professionals who regulate the safety of medicines (Medicines and Healthcare Products Regulatory Agency) have warned against the use of a turmeric based supplement known as Fortodol or Miradin. These contains a strong anti-inflammatory drug (anti-inflammatories are used for pain relief. Examples include ibuprofen and naproxen) called Nimesulide which can severely damage the liver. It is not licensed to be used as a medicine in the UK.

If you are considering taking any form of turmeric supplement, please speak to your doctor or breast cancer nurse first.

Cancer Research UK and the Memorial Sloan Kettering Cancer Centre have a range of further information on the use of turmeric as a dietary supplement.


Cancer and meat

There is lots of research evidence confirming a link between red and processed meats and cancer. Processed meat includes sausages, bacon, ham and salami. Red meat includes all fresh, frozen or minced beef, pork or lamb.

A number of different chemicals in the meat (either naturally occurring, adding during processing or formed during cooking at high temperatures) are thought to damage cells, leading to cancerous changes.

Whilst not directly linked to breast cancer, eating lots of processed and red meat is known to increase the risk of bowel cancer and potentially stomach and pancreatic cancer.

It is a good idea to cut down the amount of red and processed meat you consume as part of an overall healthy lifestyle approach. Try increasing the number of ‘meat free’ days you have or swapping red and processed meats for fresh chicken or white fish.

Cancer Research UK have a scientific blog series which has covered the topic of cancer and meat.


Cancer and soy

Soy (or soya) is a non-meat source of protein which is found in lots of vegetarian and vegan foods such as tofu (bean curd), soybean burgers and soy milk. Soy foods are very good sources of protein, as well as being high in key nutrients such as the B vitamins, potassium, magnesium and fibre. They are made from soybeans, which contain plant-based chemicals known as isoflavones. The structure of isoflavones is very similar to the human hormone, oestrogen, though they tend to have much milder effects.

There are lots of conflicting (opposite or opposing) claims about soy and breast cancer, as well as other health conditions. Some state that foods containing soy have lots of health benefits, protecting against osteoporosis (thinning of the bones), hot flushes in menopause and cancers which are driven by hormones such as breast (in some cases) and prostate.

On the other hand, there are also claims that soy products may in fact cause breast cancer.

It is important to look to the evidence.

Before we do, there are a few things to bear in mind.

Interestingly, lots of the studies looking into a link between soy and cancer are carried out in Asian countries, where peoples’ diets tend to contain a much higher amount of soy. This means that findings may not necessarily be relevant to the UK, where we tend to eat much smaller amounts of soy.

Soy may also behave differently in our bodies than it does in the bodies of animals. This means that evidence from studies conducted in animals may not necessarily translate or apply to humans.

In studies looking at soy and breast cancer specifically, a woman’s age and whether or not they have reached menopause appears to affect the actions of soy in the body. Soy also appears to have an effect in some types of breast cancer and not others.

Some studies have found soy reduces the risk of breast cancer whilst others have found no association between soy and breast cancer. [1, 2, 3, 4].

In studies looking at animals and cells, soy has been found to encourage breast cancer growth. However, in studies which observe humans who consume soya products over a period of time, they are shown to be protective (to reduce the risk of developing breast cancer) or to have no effect at all.

Whilst women from Asia have been found to get the greatest benefit in terms of how much they are protected from breast cancer, this may simply be because they eat larger amounts of soy than women from America and Europe.

Overall, continued research is needed for us to better understand this link. For now, the consensus is that it is fine to include soy and soy containing foods in moderate quantities as part of normal diet, but women should avoid taking soy containing supplements.

Harvard University School of Public Health’s website has range of further information on the evidence behind soy, health and disease.


  1. Sacks FM, Lichtenstein A, Van Horn L, Harris W, Kris-Etherton P, Winston M. Soy protein, isoflavones, and cardiovascular health: an American Heart Association Science Advisory for professionals from the Nutrition Committee. Circulation. 2006 Feb 21;113(7):1034-44
  2. Trock BJ, Hilakivi-Clarke L, Clarke R. Meta-analysis of soy intake and breast cancer risk. Journal of the National Cancer Institute. 2006 Apr 5;98(7):459-71.
  3. Michels KB, Mohllajee AP, Roset‐Bahmanyar E, Beehler GP, Moysich KB. Diet and breast cancer: a review of the prospective observational studies. Cancer: Interdisciplinary International Journal of the American Cancer Society. 2007 Jun 15;109:2712-49.
  4.  Linos E, Willett WC. Diet and breast cancer risk reduction. Journal of the National Comprehensive Cancer Network. 2007 Sep 1;5(8):809-16.

Other sources

The dairy-free diet

The dairy food group is made up of milk and other products which are made (derived) from milk, including cheeses and yoghurt.  

Dairy is an essential aspect of a healthy, balanced diet, since these foods provide us with key vitamins and nutrients, including vitamin B2 and B12, iodine, calcium and protein. Calcium is very important for forming and maintaining strong, healthy bones, iodine for healthy nerve and brain functioning and protein for growth and repair in the body. Vitamin B2 is needed to allow us to release energy from carbohydrates and protein, whilst B12 is essential for the health of nerves and red blood cells.

Nutritionists advise opting for lower fat dairy options, such as low fat cheeses and skimmed or semi-skimmed milk, since these are still great sources of calcium and other nutrients whilst also containing less saturated fat.

In the absence of dairy, dairy alternatives such as soy milk, oat milk or soy yoghurt can help to ensure that we don’t miss out on these important vitamins and nutrients.

Some people need to cut out dairy, whether due to an intolerance or allergy, whilst others may choose to as part of a plant-based (vegan) diet or because of health claims they may have heard in the media.

Dairy: is there a link to cancer?

There has been lots of research carried out to explore whether there is a link between dairy and cancer but the results have not been clear and so far we do not have strong evidence to suggest that eating dairy products can lead to cancer.

In summarising the available evidence, the World Cancer Research Fund conclude that there is some limited evidence to suggest a reduced risk of breast cancer (pre-menopausal) in people whose diets contain dairy, a probable link between dairy and a reduced risk of bowel (colorectal) cancer and some limited evidence to suggest that dairy may cause an increased risk of prostate cancer.

Some people are concerned about the possibility of there being hormones in milk, which may have an affect on health.

The Food Standards Agency carefully monitors and regulates what is contained in our milk and makes sure milk and milk products are safe to consume.

In some countries, the hormone bovine somatotrophin (BST) is used to speed up the production of milk and meat. This is NOT allowed in the UK and the rest of Europe and we do not import meat from countries where BST is used. However, this is not due to concerns for human health, rather for the welfare of animals. Experts on the European Union Scientific Committee reviewed the evidence and concluded that BST does not pose a risk to human health.

If you do cut down or cut out diary products from your diet, for whatever reason, it is important that you include calcium-fortified (i.e. added calcium) dairy alternatives. These include rice, oat, soya and nut milks, yoghurts and cheeses. Speak to your doctor, nurse or dietitian before making any dietary changes.


The Alkaline diet

The alkaline diet and claims of its cancer curing or cancer protective effects is another topic which has received lots of media coverage.

The idea behind this diet is that cancer cells are able to thrive in acidic environments. Therefore, it is claimed that by eating lots alkaline (the opposite of acidic) foods, such as green fruit and vegetables, acids are neutralised (made less acidic) and cancer cells are unable to survive.

Your body’s pH is a measure of how acidic your blood is. This is very carefully regulated and balanced by your kidneys and lungs. The foods we eat have very little effect on our body’s pH. Any extra acids or alkalis we do take in are usually passed out in the urine when we empty our bladder.

A benefit of the alkaline diet is that it encourages you to eat lots of fruit and vegetables. However, these benefits are down to the vitamins, nutrients and fibre we get from fruit and vegetables, not because of any effect on the acid balance (pH) in the body.

Whilst the diet itself isn’t necessarily unsafe, there is a real risk that following a strict alkaline diet would cause you to lose out on and become deficient in (i.e. not have enough) other important vitamins, nutrients and protein. If you are considering following an alkaline diet, it is therefore very important to speak to a dietitian or nutritional expert to make sure that you are still getting everything that you need.

The University of California have published a blog post with input from an expert dietitian which explains the alkaline diet in detail.

The topic is also covered in Cancer Research UK’s myth busting science blog.


The Paleo diet

The Paleo or Paleolithic diet is based upon the diets of our ancestors would have eaten 10,000 years ago. Followers of this diet believe that, in only consuming the foods that hunter gatherers would have been able to eat, they will be able to avoid the illnesses and health conditions which have developed with modern day lifestyles.

A Paleo diet includes fruits, vegetables, meats & fish, eggs, nuts & seeds and healthy oils (including olive, coconut and flaxseed). It also requires followers to cut out sugar, salt, potatoes, vegetable oils and all dairy, grains and legumes (e.g. beans, peas, lentils, chickpeas, soybeans and peanuts).

At first glance, this seems reasonably healthy. It is rich in healthy proteins & fats and fresh fruits & vegetables and low in sugar and salt. However, because it cuts out major food groups, the Paleo diet is not a complete, balanced diet. Without any dairy, it is difficult to get enough calcium in the diet and cutting out grains and legumes puts people at risk of becoming deficient in essential B vitamins. Vegetarians would struggle to get enough protein from a Paleo diet, since all dairy products and legumes (which includes soybean and tofu) are ruled out.

As for the potential of the Paleo diet to prevent diseases of the modern day such as cardiovascular (heart) disease and type II diabetes, the evidence does not exist. To reduce the risk of cardiovascular disease, evidence actually support diets high in grains and legumes. Similarly, claims that the Paleo diet can help prevent osteoporosis are confusing, since we know that calcium is essential for bone health and this diet promotes cutting out all calcium-rich dairy products.

Currently, there is no strong evidence to support claims that the Paleo diet can prevent or improve disease or health conditions. Realistically, our idea of what our ancestors diets was made up of, and in what quantities, is based on ancient remains and assumptions. The Paleo diet doesn’t consider the very different lifestyles they would have led all those thousands of years ago, living outdoors and likely being very physically active, and the impact this would have had on their health.

Overall, the Paleo diet encourages key healthy principles such as eating plenty of fresh fruit and vegetables and cutting down on processed food, salt and sugar. Yet these principles would be better followed as part of a complete, balanced diet to prevent the risk of becoming deficient in (not have enough of) key vitamins and nutrients. 


Harvard Health Publishing: The Paleo Diet – Back to the Stone Age

The Keto diet

The Keto or Ketogenic diet is high in fat and low in carbohydrate, with a reasonable amount of protein.

The body needs glucose for energy. Normally, it is able to break down carbohydrate to release glucose.  When following a keto diet, since the body is taking in less carbohydrate, it isn’t able to get energy in the usual way. Instead, it is forced to release glucose by breaking down fat from the diet or from body stores. This process is known as ‘ketosis’.

The keto diet was first developed to help treat children with epilepsy and it has recently been suggested (in research carried out in 2018) that it has the potential to help in the treatment of cancer [1].

Scientists are looking at whether this could be used to support the treatment of cancer since, unlike normal body cells, some cancer cells are unable to get energy by ketosis. While normal body cells can adapt (change or shift) to get their energy by this alternative process, cancer cells are dependent on getting it from carbohydrates in the usual way. This means that they could starve due to lack of glucose [1,2].

Recently, there has been promising evidence for anti-cancer effects of the keto diet (i.e. that it stops cancer growing) in what are known as pre-clinical studies. These are studies carried out on animals or cells to work out whether it is then safe to perform the scientific study on humans. However, to be able to prove that this effect could be used in cancer treatment, there needs to be scientific trials showing these positive effects in humans. This is what is currently lacking. Importantly, some pre-clinical studies have also shown that the keto diet in fact caused growth of the cancer (i.e. a ‘pro-tumour’ effect). Though this has been seen much less frequently than the anti-tumour effect, much more research is needed to make sure we fully understand how and why this happens, and whether this is the case for particular cancers or people with particular genes, before the keto diet can be recommended as a safe ‘adjuvant’ treatment for cancer (i.e. used alongside or in addition to usual cancer treatment) [1, 2].

Scientists and researchers are now calling for randomised controlled trials (i.e. a study where human participants are randomly selected to either receive the thing we are studying or to NOT receive it and the two groups are then compared. In this case, they would look to compare the effect of patients with different cancers being treated with usual treatment plus the keto diet with patients treated with usual treatment and a normal diet). This will allow us to confirm whether the promising effects so far seen in preclinical studies are also found in humans and are significant enough to support cancer treatment [1, 2, 3]. 


  1. Weber DD, Aminazdeh-Gohari S, Kofler B. Ketogenic diet in cancer therapy. Aging (Albany NY). 2018 Feb;10(2):164.
  2. Weber DD, Aminzadeh-Gohari S, Tulipan J, Catalano L, Feichtinger RG, Kofler B. Ketogenic diet in the treatment of cancer-where do we stand?. Molecular metabolism. 2019 Jul 27.
  3. Klement RJ. Beneficial effects of ketogenic diets for cancer patients: a realist review with focus on evidence and confirmation. Medical Oncology. 2017 Aug 1;34(8):132.

Other sources

BBC Food: Is a keto diet the best way to lose weight?

Further information on diet & nutrition

If you have come across a headline or news story which discusses a particular food, diet or supplement in relation to cancer, you can check the evidence behind the claims by visiting ‘NHS behind the headlines’.

Please also see our section on How to read the evidence.

You can also speak to a dietitian about any questions or queries you might have using Macmillan’s online ‘ask the expert’ forum.

Though it is not specific to living with advanced cancer, you may also find Macmillan’s guide on ‘Healthy eating and cancer’ useful.

Page last updated: April 2020