Can diet affect my risk of cancer?

Lizzie Tuckey
Director of Clinical Strategy, Bupa
07 November 2017

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This article is more than three years old. It reflects the best available evidence at the time of publication.

These days, we all know that smoking and getting sunburnt will increase your cancer risk. If we’re sensible, we avoid both. But what about what you eat? It sometimes seems as if hardly a day goes by without us hearing that something we eat or drink causes cancer. It gets really confusing, so we want to take a closer look at the evidence.

What we know for sure

One of the most important ways diet can affect your risk of cancer is through weight gain. Being overweight increases the risk of 13 different types of cancer, including bowel cancer and post-menopausal breast cancer. The World Health Organisation says that overweight and obesity is the most important avoidable cause of cancer, apart from smoking.

The good news is that if you follow the healthy eating guidelines for preventing both cancer and cardiovascular disease, you’re likely to keep to a healthy weight.

There’s good evidence that eating plenty of fruit and vegetables can reduce your risk of mouth, larynx and lung cancers. You’ll also be getting plenty of fibre in your diet – and that lowers your risk of bowel cancer.

There’s also strong evidence that alcohol increases the risk of many types of cancer. And too much red and processed meat in your diet increases bowel cancer risk. Processed meat means sausages, bacon, ham and salami.

Early evidence

Cancer researchers are now interested in foods that cause a rush of blood sugar. You may have heard of ‘GI diets’. This stands for ‘glycaemic index’ – and tells you how quickly or slowly a food causes your blood sugar to rise. High-GI foods cause the blood sugar to rise rapidly. There is some evidence that these can increase risk of cancers, including bowel breast and womb cancers. High-GI foods include white breads, sugary drinks, white rice, biscuits, potatoes and some dried fruits, such as raisins and dates. So far, the evidence suggests that a high-GI diet may result in a small or moderate increase in cancer risk. But high-GI foods also increase your risk of diabetes and heart disease, so cutting down is clearly good for our overall health.

Unfortunately, only around three in ten people in the UK have heard of the glycaemic index. In Australia, manufacturers now have to label food products as low or high GI and now more than eight out of ten people are aware of the importance of GI in diet. It seems likely that introducing GI to food labels could help to raise awareness here.

Yet to find out

Many people worry about exposure to chemicals, such as pesticides, and cancer risk. The European Union has stricter regulation than many other developed countries so fortunately for us, pesticides linked to cancer that are allowed in some other countries are banned here.

The UK Food Standards Agency say that pesticide residues in UK foods are too low to be a risk to health. But there is now some evidence of a link between working with pesticides and cancer risk. So it makes sense to take precautions if you’re using them in the home or garden.

What you can do

So how do we make sense of all this? Well at the risk of boring you all, there’s little new under the sun. On the plus side, that makes it all easier to remember! So …

  • Keep to a healthy weight – your BMI should be less than 25.
  • Eat plenty of fruit and veg – this should make up at least half your plate for main meals.
  • Eat white meat and fish in preference to red and processed meats.
  • Cut down on carbohydrates that cause a rapid rise in blood sugar – white bread and rice, potatoes, sugary drinks, cakes and biscuits.
  • Choose wholegrain breads, pasta and brown rice to keep up fibre intake.
  • Keep below the recommended maximum of 14 units of alcohol per week.
  • Wash fruit and veg before eating to remove pesticide residues.
  • Wear gloves when handling home or garden chemicals and of course, keep out of the reach of children.

Nobody likes to think about being diagnosed with cancer. But our health insurance gives you personal cancer care with support at every stage of your treatment for as long as you have a policy with us. Learn more about our health insurance.

Lizzie Tuckey
Dr Lizzie Tuckey
Director of Clinical Strategy, Bupa