Diet and food supplements

You may make changes to your diet to improve your overall health, or to cope with the effects of cancer and its treatment. Nutritional therapies cannot cure cancer. But following a healthy diet is one of the most important changes you can make for your health.

Nutritional therapists work with you to find a diet that suits your needs. They may use detoxing, high-dose vitamins or avoiding certain food groups to try to improve your health. If you’re lacking essential vitamins, minerals and essential fatty acids, dietary supplements can help. These can be particularly beneficial for people with cancer who struggle to get the right nutrients.

Always speak to your doctor before taking any nutritional therapies. Some supplements, for example antioxidants, can affect how well your cancer treatment works. Some may even increase the risk of some cancers developing.

What are diet and food supplements?

Many people make changes to their diet after a cancer diagnosis as a way of staying as healthy as possible. They may also do this to help their body cope with the effects of cancer and its treatments. Giving up smoking, increasing physical activity and following a healthy diet are the most important changes people can make for their health.

For most people, making these types of changes will make the biggest difference to their health. They can be more helpful than making any one particular change.

People often ask about ‘superfoods’ or foods that boost the immune system. But there isn’t any medical evidence that suggests these work.

There still isn’t enough clear information to make exact recommendations about what someone with cancer should eat. In general, cancer experts recommend following a healthy, balanced diet. Your healthcare team (this includes your GP, doctors and nurses) are the best people to advise you what, if any, lifestyle changes you can make that may help.

We have more information about Healthy eating and cancer and a useful video with tips for healthy eating.

Nutritional therapists

Nutritional therapists don’t aim to cure cancer through diet but try to improve your health. They use methods such as detoxing, high-dose vitamins or avoiding certain food groups.

There’s no medical evidence that nutritional therapy can reduce the chance of cancer coming back and no reliable research has shown that it can improve health.

Nutritional therapists assess your general health and recommend a diet that’s thought to be specific to your needs. Nutritional therapists are different from dietitians. Dietitians use current medical evidence to give specific advice to people with eating or weight problems as well as advice on healthy eating in general. Your doctor or nurse can refer you to an NHS dietitian.

Dietary supplements

We need nutrients such as vitamins, minerals and essential fatty acids for our bodies to work properly. The best way to get these is by eating a healthy diet. However, some people with cancer aren’t able to get all the nutrients they need from their diet. This may be because of problems with eating or because their bodies aren’t able to absorb the nutrients.

If you’re concerned about your diet or nutrition, ask your doctor or nurse to refer you to a dietitian. They can give you advice on what to eat and may prescribe nutritional supplements for you. If you aren’t able to eat a healthy balanced diet, your doctor may prescribe a daily multivitamin and multi-mineral supplement. This will give you the recommended daily allowance (RDA) of the nutrients you need.

If you’re thinking of taking dietary supplements, it’s important to talk to your cancer doctor first.

Some people think that if something is good for you in small amounts, taking larger amounts is even better. But this isn’t always the case. Nutrients, which are essential for our health in small amounts, can be harmful and cause unpleasant side effects when taken in large amounts. And some may interact with, or lessen the effectiveness of, cancer treatments.

Despite a lot of research into cancer and dietary supplements, there isn’t enough evidence to suggest that taking them can help treat cancer or stop it from coming back. But, research has found that taking certain supplements could increase the risk of some cancers developing.


Antioxidants such as vitamins A, C and E, coenzyme Q10 and selenium are some of the most commonly taken dietary supplements.

Antioxidants can help to prevent cell damage. Because of this, some doctors have concerns that taking antioxidant supplements during cancer treatment may make cancer treatment less effective. Your cancer doctor may recommend that you don’t take antioxidant supplements during your treatment, unless it’s as part of a clinical trial.

If you’d like to discuss dietary supplements and get more information, call us on 0808 808 00 00.