Answering your questions about diet and exercise during cancer treatment.
> Do I need to follow a fad diet?
> Is a vegan diet safe during cancer treatment?
> Should I avoid sugar?
> Should I avoid soy if I have breast cancer?
> Is it safe to exercise during and after cancer treatment?
> Should I continue with my medication if I follow your recommendations?
> What about supplements and natural remedies?
> Is your advice for people living with cancer endorsed by dietitians?
> How do I know your advice is reliable?
> Is your advice safe for all adults with cancer?
> What if my doctor’s advice conflicts with your advice?
> Where do I go for further advice and support?
‘Fad’ diets (diets that are very restrictive, include few foods or focus on unusual combinations of foods) that claim to help you fight cancer can seem very appealing and get a lot of media attention. However, there’s no scientific evidence that following any type of diet can cure cancer or replace cancer treatments.
Also, following a ‘fad’ diet while you’re having treatment can have risks, such as not providing your body with all the nutrients it needs.
Of course! But if someone is following a vegan diet because they think they “must”, rest assured that whilst we know eating more plant-based foods is good for our health, there is no evidence that a strict vegan diet provides any advantages. There is some evidence that eating foods containing soy and fibre may reduce the risk of breast cancer recurrence.
> Read more on this topic
All cells need fuel for energy. The primary fuel is a simple sugar, glucose, which is processed by cells to release energy.
In the 1920s, a German scientist called Otto Warburg found that cancer cells use up a lot of glucose. It isn’t clear why cancer cells do this but it may have advantages in ensuring sufficient building blocks are available for rapidly dividing cells.
More recent research has looked into using diet therapy to ‘starve’ cancer cells of energy. By removing dietary sources of glucose it is suggested that cancer cells would not be able to fuel growth and replication, even though the body is able to produce glucose in the absence of dietary sources.
Most studies have focused on the ketogenic diet, which restricts intake of sugar and carbohydrates to very low levels.
A 2018 review of all the available studies on the ketogenic diet and people living with cancer found that overall there was not enough high-quality research.
Population studies do not indicate increased risk for breast cancer survivors who consume soy. In fact, limited evidence shows the potential for greater overall survival and perhaps decreased recurrence among women a year or more after diagnosis who include moderate amounts of soy. For now, there is no reason to steer clear of soy foods, and there is also no reason to consider them must-haves if people prefer not to include them in their diet.
There’s growing evidence that people who are active before and after a cancer diagnosis have a better chance of survival.
Generally, it’s safe, and beneficial, for people with cancer to exercise. However, it’s best to start slowly and build up if you aren’t used to exercising regularly.
Let your doctor or nurse know if you want to be more active as they may be able to signpost you towards a specialist who can give you individual advice and support.
> Read more on this topic
> Is swimming safe for people with cancer?
There’s no scientific evidence that changes to your diet or lifestyle can cure cancer, so it’s vital to continue taking prescribed medication as instructed by your doctor.
If you feel you no longer need a certain medication, do make sure you discuss this with your doctor before you stop taking it.
As with all medication, make sure you ask your doctor or a pharmacist, or read the patient information, to check if it interacts with any foods or drinks.
We advise people to get all their nutrients from their food and drinks, where possible. If you aren’t able to eat as normal, your doctor or dietitian may prescribe supplements for you. It is important that you take these as suggested.
However, if you’re considering taking other supplements or homeopathic, natural or herbal remedies that haven’t been prescribed for you, you need to discuss this with your doctor before you start taking them to check they are safe for you.
The advice in this section of the website, and the information contained in our Eat well during cancer booklet, is endorsed by the British Dietetic Association (BDA), the only body in the UK representing the whole of the dietetic workforce. Founded in 1936, the BDA is one of the oldest and most experienced dietetic organisations in the world.
BDA specialist dietitian Deborah Howland (left) says: “When going through cancer, eating can be a challenge and knowing what to eat can be very difficult and sometimes confusing. That’s why Eat Well During Cancer is an important piece of work which will be a real help to many people living with cancer.
“The booklet features some invaluable tips on how different foods can help people cope with some of the common side-effects of cancer treatment. It has the benefit of being written with specialist dietitians so people can be confident that the information is not only accurate but practical. The booklet won’t only be useful for patients but for health professionals too.”
The booklet has also been recognised by doctors, and was commended in the 2018 BMA Patient Information awards.
Our advice for people living with cancer has been written by World Cancer Research Fund’s team of experienced nutritionists, with the support of dietitians from the Oncology Specialist Group of the British Dietetic Association (BDA).
The BDA’s backing ensures our advice is based on the most up-to-date scientific evidence and practical expert advice.
Our advice has been written in conjunction with specialist oncology dietitians, and should be safe to follow for most adults who have cancer. However, it’s a general guide and is not suitable for people who are eating very little, have lost a lot of weight unintentionally or are receiving end-of-life treatment – people in these groups will need specialist information and advice.
If you follow a special diet for another medical condition, such as heart disease, diabetes or renal failure, or have had a colostomy or ileostomy, this website may not be suitable for you. Talk to your doctor or dietitian about safe changes to make to your diet.
Where the advice in this section of our website differs from the advice given to you by your doctor or dietitian, it’s always best to follow their advice as it will be specific to your needs.
It should also be noted that many of the specific suggestions in this section of the website, while safe, will not help everyone – they are suggestions that other people have found helpful and that you might also want to try.
Our Support and advice page provides information on some of the many organisations that offer help to people living with cancer, and their familes. If you are nearing the end of your treatment, you may find our booklet Healthy living after cancer useful.
