Commonly asked questions about diet

Can diet reduce the risk of cancer coming back?

People often ask if what they eat can reduce their risk of the cancer returning. This is the subject of a lot of research. There is some early evidence from breast and bowel cancer studies that diet may make a difference to the chances of the cancer coming back.

But there still isn't enough clear information to make precise recommendations about what someone with a particular type of cancer should eat. In general, cancer experts recommend following a healthy balanced diet.

For most people, the factors that are most likely to have the greatest impact on your health include diet, weight control and regular physical activity. The biggest difference will probably be from a combination of factors, rather than from making any one particular change.

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 reduce your risk of cancer coming back.

What foods should I avoid when I have low immunity?

Make sure that eggs are well-cooked, and use shop-bought, not home-made mayonnaise. If your immunity is low, avoid paté, raw eggs, live bacterial yoghurt and cheeses made from unpasteurised milk, such as Brie and blue-veined cheeses. These foods may contain harmful bacteria.

If you’re on high-dose chemotherapy, your healthcare team may suggest that you avoid additional foods – ask them for advice.

Should I take dietary supplements?

For most people, a balanced diet provides all the nutrients they need, and taking large doses of vitamins, minerals and other dietary supplements isn't recommended. But people who find it difficult to eat a balanced diet may benefit from taking a multivitamin or mineral supplement containing up to 100% of the recommended daily allowance.

Supplements may be beneficial in some situations, such as for people who aren't able to absorb all the nutrients they need because of surgery for stomach cancer. People at increased risk of bone thinning (osteoporosis) may benefit from taking calcium and vitamin D supplements to help strengthen their bones.

Several studies have looked at whether taking supplements can reduce the risk of developing certain cancers. But the results have been disappointing, and in general the evidence is that taking supplements doesn't reduce the risk of cancer. There is even evidence that taking high doses of some supplements can increase the risk of cancer developing in some people.

One study found that people who smoke were more likely to develop lung cancer if they took supplements of beta-carotene (a substance the body uses to make vitamin A). And the results of other studies suggest that high doses of beta-carotene and vitamin A supplements may increase the risk of getting cancers of the gullet and stomach.

It’s possible that some supplements may interfere with how cancer treatments work, and make them less effective. So if you're currently having treatment for cancer, it’s important to get advice from your cancer specialist before taking any supplements. They can advise you about which, if any, you should take, and which doses might be suitable for you. They can also tell you about any possible side effects and interactions with other medicines.

What about ‘superfoods’?

There isn't any scientific evidence for any one particular food being a 'superfood'. The greatest benefit to your health is likely to come from eating a balanced diet that includes a wide and varied combination of foods.

There are many substances in fruits and vegetables that may potentially have anti-cancer properties. However, at the moment we don’t know this for certain, and we don’t understand which ones are most likely to help or how they work.

So instead of looking for a 'superfood', it’s better to aim for a 'superdiet' as recommended in healthy eating guidelines. This will help you make sure you’re getting the widest possible variety of these substances. It will also make your diet more enjoyable and interesting, and it will probably be cheaper too.

Should I follow a dairy-free diet?

Many research studies have looked for a link between diets that are high in dairy products, and cancer (in particular breast and prostate cancer). But these studies haven’t shown a clear link. Because of this, cancer experts don’t recommend following a dairy-free diet to try to reduce the risk of cancer.

Dairy products are an important source of protein, calcium and some vitamins, but can be high in fat. Choose low-fat products to avoid putting on weight. Calcium is needed for strong bones and may help reduce the risk of bowel cancer. So if you decide to follow a dairy-free diet, you’ll need to make sure you get enough calcium from other food sources, such as tinned sardines and salmon (with bones); dark green leafy vegetables, such as spinach; or fortified foods, such as some types of soya milk.

Does sugar feed cancer?

Sugar in your diet doesn't directly increase the risk of cancer, or encourage it to grow. But sugar contains no useful nutrients, apart from energy, and we can get all the energy we need from healthier sources. So it's best to limit the amount of sugar in your diet.

Should I only eat organic food?

Many people wonder if they should follow an organic diet to prevent cancer from coming back. Studies that examined the nutritional benefits of organic fruit and vegetables had mixed outcomes. Some claim that organic fruit and vegetables have better flavour and stay fresh for longer. So far, no research has been done to find out if an organic diet is more effective at stopping the recurrence or occurrence of cancer, compared to a non-organic diet.

Some people may worry that pesticides used in non-organic farming may cause cancer. In the UK, a pesticide can only be used once its safety has been tested. Laws ensure that all agricultural pesticides are used within a safe level.

Genetically modified (GM) crops have proved to be safe in the seven years they’ve been grown. But some people might feel that the long-term effects are unknown.

Buying organic or non-organic food is ultimately a personal choice. The current advice is to wash all fruit and vegetables, non-organic as well as organic, thoroughly before use to remove any form of pesticide.

Do anti-cancer diets work?

There has been a lot of publicity about alternative diets for treating cancer over the past few years. Many dramatic claims for cures have been made. It’s understandable that people may be attracted to diets that seem to offer the hope of a cure. However, there isn’t good evidence that these diets can make a cancer shrink, increase a person’s chance of survival, or cure the disease.

Some people get satisfaction from following these special diets, but others find them quite boring and even unpleasant to eat, and time-consuming to prepare. Some diets may lack important nutrients or be unbalanced in other ways, and may even be harmful.

It can be confusing to be faced with conflicting advice about what to eat, but most doctors and specialist nurses recommend a well-balanced and enjoyable diet.

Back to Healthy eating

Diet and cancer

Eating a healthy, balanced diet and keeping to a healthy weight can help reduce the risk of developing some cancers.

Staying healthy

A balanced diet will provide everything you need to keep your body healthy. It will contribute to your well-being.