Healthy eating and cancer

Healthier diets could help prevent up to one-third of cancers (30%) in the UK. Some foods may increase our risk of cancer, but others may protect us.

Diet and cancer

Healthier diets could help prevent up to one-third of cancers (30%) in the UK. A lot of research is being done into which types of food may affect your risk of developing cancer.

Research shows that being overweight increases the risk of developing some types of cancer. There are many reasons why people are overweight. But an unhealthy diet and lack of physical activity are often factors.

Some foods may increase our risk of cancer, but others may protect us. The link between diet and the risk of developing cancer is complicated. Scientists still do not completely understand it. Research suggests that eating more fibre may reduce the risk of certain cancers. Eating a lot or red and processed meat may increase the risk of bowel cancer. We have some answers to common questions about food and cancer.

What we do know is that a healthy, balanced diet and regular exercise helps us keep to a healthy weight. This can help reduce the risk of developing some cancers.

Booklets and resources

Why is a healthy diet important?

Food has nutrients that our bodies need. The main groups of nutrients are carbohydrates, proteins, vitamins and minerals, fats, fibre and fluids.

A healthy, balanced diet gives you all the nutrients you need to keep your body working well. For most people, this includes:

  • lots of fruit and vegetables – at least 5 portions a day
  • plenty of starchy foods (carbohydrates) – choose wholegrain types such as wholemeal bread, rice, pasta, noodles, couscous and potatoes
  • some protein-rich foods, such as lean meat, poultry, fish, nuts, eggs and pulses (beans and lentils)
  • some milk and dairy foods, such as cheese and yoghurt.

You should limit foods that are high in fat and sugar. This is because they often do not have any additional vitamins or minerals. High-fat or sugary foods give you a large amount of energy, but they can cause weight gain. Choose unsaturated fats, such as nuts, avocados and olive oil.

Try to reduce the amount of processed and red meats you eat. You should also avoid foods which have a lot of salt or sugar.

It is best to drink water or unsweetened squashes that contain no added sugar. You can also drink tea and coffee (without sugar). If you drink fizzy drinks or sugary squashes, try to reduce the amount you drink and have the diet, sugar-free types instead. Try to limit the amount of fruit juice you drink to 1 glass a day (150ml), as these also contain sugar. It is better to eat whole fruits.

Having a healthy, balanced diet is one of the best choices you can make for your overall health. This includes thinking about what and how much you drink. Many people find making the decision to follow a healthy, balanced diet helps give them a sense of control. It can also help you feel that you are doing the best for your health.

Eating well and keeping to a healthy weight will help:

  • you feel stronger
  • increase your energy levels
  • keep your immune system healthy
  • improve your sense of well-being.

It can also help reduce the risk of new cancers and other diseases, such as heart disease, diabetes and strokes.

It is important to eat well when you are getting ready for cancer treatment. We have information about this in our videos about prehabilitation

After cancer treatment, some people have a higher risk of other health problems. This can include diabetes, heart disease or osteoporosis (bone thinning). If you have been told that you are at increased risk, it is very important to follow a healthy diet to help prevent them. Some people also need to make changes to their diet if cancer treatment has affected their immune system.

We have more information about different food types.

Keeping to a healthy weight

It is not healthy to be overweight or underweight. Eating too much can make you overweight. This can lead to health problems such as:

  • heart disease
  • high blood pressure
  • diabetes.

Eating less food than your body needs can make you underweight. This can also affect your health.

Many people in the UK are heavier than the recommended weight for their height. And some types of cancer treatment, such as hormonal therapy or steroids, can lead to weight gain.

Losing weight can be difficult. But trying to keep to a healthy weight is one of the best ways to reduce your risk of developing cancer. Being overweight increases the risk of many types of cancer including bowel, kidney, womb and oesophageal (gullet) cancer. Women who are overweight and have been through the menopause have an increased risk of breast cancer. Being a healthy weight may also help reduce the risk of some cancers coming back.

Being overweight may increase the chances of complications if you need surgery.

Try to keep your weight within the normal range for your height. Body mass index (BMI) is a way of measuring if you are a healthy weight for your height. Your GP or nurse will work out your BMI for you. There is also a BMI calculator on the NHS website.

If you are concerned about your weight, ask your GP or a dietitian for advice and support. Dietitians can give you advice about food choices that are more healthy but still make you feel full.

Be patient with yourself. Losing weight is a gradual process. It is important to eat a healthy, balanced diet to make sure you get all the nutrients you need to keep your body healthy. It is reasonable to aim to lose about 0.5 to 1kg (1 to 2 pounds) a week.

Tips for keeping to a healthy weight

  • Only eat as much food as you need. This depends on how active you are. You may need to talk to a dietitian about this.
  • Eat a healthy diet with lots of fruit and vegetables and less fat and sugar.
  • Try to be physically active.


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About our information

  • References

    Below is a sample of the sources used in our healthy eating information. If you would like more information about the sources we use, please contact us at

    Fang X et al. Quantitative association between body mass index and the risk of cancer: A global Meta-analysis of prospective cohort studies. International Journal of Cancer. 2018 Oct 1;143(7):1595-1603.

    British Nutrition Foundation website (accessed December 2019).

    Bhaskaran K et al. Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5·24 million UK adults. The Lancet, August 2014..

    The Eatwell Guide: Helping you eat a healthy, balanced diet, Food Standard Scotland, October 2019.

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 01 August 2020
Next review: 01 August 2023

This content is currently being reviewed. New information will be coming soon.

Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.