Cancer

What we choose to eat is one of the factors involved in cancer risk. It's estimated a third of cancers could be prevented by making healthier food choices, being physically active and having a healthy body weight
What is cancer?
The growth and function of all the cells in our body are carefully controlled by many processes. The term cancer is used when these control systems go wrong and our cells start to grow out of control. The process usually involves damage to the DNA in cells, which can be caused by chemicals found in cigarette smoke, radiation and even some viruses. The food we eat also affects DNA function, but the exact mechanisms are unclear.

In most cases, cancer is caused by many different factors, with several processes being involved in DNA damage in cells.

Food and the prevention of cancer
The link between diet and cancer is complicated, and scientists have not yet unravelled the exact mechanisms involved. This is because diets are made up of different foods containing many nutrients that interact in different ways in individuals.

Nutrition scientists need to study very large groups of people over many years to give us more specific answers to how and what foods increase the risk of cancer. These studies are ongoing, but the World Cancer Research Fund has examined all the existing evidence.

It has produced recommendations on food, nutrition and physical activity to help reduce the risk of cancer, based on current scientific evidence.

Achieve and maintain a healthy weight
Aim to stay in the healthy body mass index range of 18.5kg/m2 to 25kg/m2.

Excess body fat is a particular risk factor for cancer of the oesophagus, pancreas, colon, rectum, endometrium and kidney, as well as postmenopausal breast cancer.

Cut calories by reducing dietary fat and eating plenty of fruit and vegetables, and foods rich in fibre. Avoid sugary drinks and keep a check on portion sizes.

Develop regular physical activity habits
Aim for at least 30 minutes of moderate activity a day, then build up to either 60 minutes of moderate activity or 30 minutes of intense activity every day.

Activity not only helps protect against weight gain but also decreases the risk of colon cancer and possibly endometrium and postmenopausal breast cancer.

Moderate activity should raise your heart rate and breathing, but not make you completely breathless and unable to talk. Examples of moderate activity include brisk walking, gardening and dancing. Examples of intense activity include jogging and swimming.

Moderate alcohol intake
Men should not exceed two drinks a day and women no more than one. Check up on the risks of alcohol and find out about sensible drinking limits.

Over the past few years, research has shown alcohol increases the risk of cancer, especially of the breast and colon.

Limit intake of red meat and avoid processed meat
Try to eat no more than 500g (18oz) each week and have very little, if any, processed meat such as bacon and salami.

Red meat is an important source of nutrients, especially iron, but we only need to eat red meat in modest amounts, probably no more than two to three times a week.

Eat foods that mostly come from plants
This means eating more fruit, vegetables and unrefined cereal foods and pulses, as they are mostly rich in fibre, low in calories and packed with the nutrients that lower the risk of cancer.

Limit consumption of salty foods
Salt and salt-preserved foods are linked to an increased risk of stomach cancer. Avoid salty snacks and don't add salt at the dinner table or during cooking - use herbs and spices to flavour food instead.

Use supplements wisely
Following the principles of healthy eating should provide most individuals with the nutrients they need to minimise the risk of cancer. There's no good evidence to show supplements will protect the general population from cancer. Some studies have shown beneficial effects of supplements in groups of people who have a high risk of developing certain cancers, but these findings can't be applied to the general population.

Cancer patients and diet
If you've been diagnosed with cancer, it’s vital you continue to eat well during treatment, as it will help you to

cope with your treatment
withstand infections
reduce the risk of nutritional deficiencies
generally improve your quality of life


Maintaining a good dietary intake can be challenging because tumour growth can increase energy needs. Also, physical symptoms such as difficulty swallowing, sore mouth, taste changes, nausea, vomiting or diarrhoea make it difficult to eat well and maintain a good weight.

Ask to see a dietitian if you're struggling to eat well - you'll receive support and specific advice for maintaining your nutritional intake. Some of these practical solutions may also be helpful:

Try to regain any weight lost during acute treatment periods
Keep ready-meals in the freezer for when you're too tired to cook
Eat regularly - keep nutritious snacks to hand
Add an extra dash of olive oil in cooking or on salads and don’t worry too much about sugar intake
Try a glass of wine to stimulate your appetite


Alternative diets for cancer prevention and treatment
There are many so-called anti-cancer diets that claim to prevent or even cure cancer. They often recommend excluding whole groups of foods or eating only a few specific foods. These diets are not supported by robust scientific evidence and tend to be based on anecdotal reports of success, so be wary of those that:

suggest excessive food restrictions
are based on eating raw foods only
recommend single large doses of supplements


Before following any diet that claims to prevent or cure disease, consult your GP or a dietitian.