Mythbusting Monday 15 July: Diet and Cancer

Cancer is incredibly common: 40% of us worldwide will receive a diagnosis of cancer in our lifetime. So of course, any way of preventing cancer is of great interest to us. Here are some points on cancer and diet from Mythbusting Monday, including some of your best questions.

What is cancer?

Cancer is not just one disease but rather a big group of different diseases. There are literally hundreds of types of cancer and the thing that they share in common is that they are a growth of abnormal cells, based on our normal cells that have lots the ability to self-regulate so they grow and divide more rapidly than a normal cell. Some of the more common cancer types are colon cancer, lung cancer, breast cancer and leukaemia. That is just a drop in the ocean.

It’s important to understand that cancer is not just one disease but whole host of them because then you will understand that there are so many causes, some known and some unknown.

Does diet cause cancer?

Cause is a strong word. Saying something causes cancer implies that if you do (or don’t do something) that the end result is cancer. It’s just not that simple. Cancer happens when the cell’s regulation is lost and that can be affected by many things, such as:

  • Ageing

  • Radiation

  • Genetics

  • UV radiation from the sun

  • Alcohol

  • Smoking

  • Some viruses (eg, HPV and cervical cancer, EBV can cause lymphoma)

  • Some dietary factors such as lack of fruit and vegetables or whole grains

  • And some factors that we don’t actually know

Is the uptick in breast cancer due to food?

No, not solely anyway. Breast cancer does have some lifestyle associations including dietary factors and exercise. But increases in breast cancer numbers is thought to be due to better screening programs picking up more tumours and an ageing population because cancer increases as we age. It’s hard to tease out and say this proportion of breast cancer is due to dietary factors because like all cancers, it happens as the result of many, many factors.

Does sugar cause cancer?

Again no one thing causes cancer and sugar is definitely the demon of the moment. There have been some studies that have been talked about a lot lately where sugary drinks increased the risk of being diagnosed with but not causing more cancer death. Again this is an association not a cause but it definitely warrants more investigation. That being said, when it comes to sugary drinks, there are plenty of good reasons to cut down (dental health, weight gain, heart disease and so on) but to say that sugar causes cancer is a bridge too far at the moment based on what we currently know.

Does eating red meat or processed meat cause cancer?

There is a reasonable amount of evidence to suggest that moderate consumption (ie. not every day) of red meat can reduce the risk of bowel cancer. There is also evidence to suggest that processed meats and charred meats may also increase cancer risk. Studies show an increase in cancer risk of the bowel around 1.1 to 1.43 times baseline. So if your original risk of bowel cancer was let’s say 10% and you eat a steak every night, your risk of bowel cancer may go up to 11-14%. There are some proposed mechanisms like substances in cooked meat that may directly damage cells, leading to the loss of regulation that leads to cancer. May. More work to be done but recommendations say to limit red meat to three times a week and this advice is sound for bowel cancer risk but also general health and sustainability issues.

Do food additives cause cancer?

Another demon of the week. People are very worried about chemicals and additives in food at the moment. Generally, stories about the dangers of chemicals aren’t supported by science. Same goes for pesticides, unless you’re bathing in them.

Is fasting beneficial in cancer?

There have been some studies that have investigated the effects of fasting on the effectiveness of chemotherapy which showed some promising results. However, there is nothing firm yet. We also need to keep in mind that getting enough nutrition for people who have cancer and are undergoing treatment is very important since cancer likes to sap all your body’s stores. There have also been some very early studies including animal studies that have come up with a maybe, but the evidence is just not good enough to recommend intermittent fasting at the moment.

Can diet cure cancer?

No. Just no.