Reviewed: Jessica Passador and Kate Kaegi, Oncology Dieticians at Austin Health
On this page: Can poor nutrition and lack of exercise cause cancer? | Overweight and obesity | Can good nutrition and exercise prevent cancer? | Can certain foods or exercise cure cancer? | Beware of ‘anti-cancer' diets | Alcohol and cancer
You may have heard that some foods are thought to cause cancer. Some people may even try to convince you that eating certain foods or avoiding others can cure your cancer. Here we'll answer some frequently asked questions relating to food and cancer.
We also look at exercise and cancer. It appears that exercise helps to prevent certain cancers. Exercising can help to speed up recovery during and after treatment and help you to feel better.
There are many different types of cancers, with many different causes. Only some of these are understood. The development of cancer is the result of complex processes in which diet and exercise can sometimes play a part.
It's unlikely that any one food will cause a person's cancer. It's more likely that general eating habits, over a long period of time, have a greater effect than any one food or food additive.
Being overweight increases the risk of several different cancers including breast cancer, bowel cancer and aggressive prostate cancers. A good diet and regular exercise will help you to keep a healthy body weight.
There are many causes of cancer and no single food or diet will prevent cancer.
Regular physical exercise appears to decrease the risk of colon cancer and breast cancer. Exercise may help reduce the chance of cancer coming back. People with cancer, or who are recovering after cancer treatment, need to discuss with their doctor or physiotherapist what level of exercise is safe for them to do.
Once a cancer has developed, no particular food or diet, or type of exercise, will cure it.
You need to eat a variety of foods to keep you well nourished during your treatment and keep your weight stable. This helps you to feel better, have more energy and be able to tolerate your treatment better.
Regular exercise has many benefits. It can help to combat fatigue, depression and muscle weakening. Unless there are particular reasons why you should not exercise, try to do some exercise on most days. This will help your body as you recover from cancer and cancer treatment.
No special foods, supplements or diets have been scientifically proven to cure cancer. Despite this, certain diets and supplements are promoted as helpful for people with cancer. Some are even claimed to cure cancer. Some of these diets could cause great harm. They may interfere with your treatment, result in poor nutrition, or lead to weight loss.
Avoid diets that remove whole food groups, such as dairy products, meat or breads and cereals, as these are important sources of nutrients in your diet. Diets that avoid these foods may not provide you with enough energy or protein. You may then become more tired and lose weight.
It's also important to be wary of dietary supplements such as high doses of vitamins, minerals and herbs. Just because they are ‘natural' doesn't mean that they're always safe. Some vitamins can be toxic in large quantities. Some dietary supplements can interact with chemotherapy, radiotherapy or medications so that treatments don't work as they should.
Check with your cancer specialist before starting a new dietary supplement to make sure that it is safe and won't affect your medical treatment.
There are a number of questions you should ask before starting any special diet or dietary supplement.
Remember to be cautious, ask questions and confirm claims. Ask your doctor or dietitian for advice before making major changes to your diet.
Alcohol can increase cancer risk. There is also increasing evidence to link alcohol intake with a risk for cancer recurrence and an effect on survival. Talk to your doctor about your situation, potential risk and any recommendations for abstaining from alcohol. It is also important for people with cancer not to replace nutrient-rich food with alcohol, as it has little or no nutritional value.