News and information
Lifestyle
Health professionals
What the experts say
The truth about diet and cancer: what we all need to know
By Professor Karol Sikora, Medical Director Cancer Partners UK
Not a day goes by without us opening the newspaper to reveal the latest ‘superfood’ with cancer-busting properties. One week it’s watercress, the next blueberries. At the same time, other foods are regularly singled out as causing cancer and other diseases. The latest advice from the World Cancer Research Fund is that parents should avoid putting ham or other processed meats into their children’s lunchboxes.
The media love the concept of cancer-busting foods, just as much as they love telling us other foods will increase our cancer risk, but it’s broadly a myth.
There is nothing especially dynamic about any one food, and eating a wheelbarrow full of watercress won’t stop you from getting cancer, just as eating a ham sandwich won’t cause it. It’s all a question of balance.
All these stories do is continue to confuse and alarm people. A poll earlier this year for BBC’s Newsnight programme found that two thirds of people have not changed their diet or lifestyle to reduce the risk of cancer. This is despite public health campaigns by groups like WCRF that highlight diet and lifestyle as a cause of between a third and half of all cancers. It’s no doubt a reflection of the fact people feel food and health ‘fatigue’ and don’t change their behaviours as a result.
These stories are not only misleading, they cause responsible parents to panic and feed the insecurities of the worried well. They also bring additional stress to patients already struggling with cancer who may blame themselves for their illness because of something they have eaten or done many years before and will need reassurance that this is unlikely to be the case.
It is generally accepted that approximately 30 per cent of cancers are caused by diet. So for scientists dietary changes can seem to be an attractive tool to fight cancer. But the problem is diet is the most complex factor in relation to cancer. And the risks and benefits from different diets may be different depending on our individual genetic make-up.
It is not just what you eat; it’s what you eat with it, how you cook it and what you don’t eat. It’s also how diet interconnects with other things in your life. Take red meat as an example – what the experts frequently overlook is that people rarely eat red meat on its own. Usually it’s eaten with vegetables, thus providing us with the protective benefits that vegetables and fibre can bring. And exercise is an important part of the dietary balance. This needn’t be marathon running or 25 mile hikes. Just walking instead of short bus journeys or using the stairs rather than lifts can have great benefit.
Despite all the research done to date on the relationship between diet and cancer, there is still no strong evidence to show that any specific foods really correlate with cancer prevention or its recurrence. It is most likely that a combination of lifestyle factors put us at more risk. Demonising an individual food group is misleading at best, and often downright unhelpful. Excluding a whole food group such as meat can also put you at risk of other health issues such as iron and protein deficiency.
The past 30 years have seen a revolution in cancer care. With far better understanding of the disease we are now able to offer increasingly effective screening and treatment. When I first started in medicine less than a third of cancer patients could expect to survive beyond five years. That figure has now risen to half of all patients.
However, there is still much we don’t know about the disease and its causes. There are certainly no magic solutions, and there is no such a thing as a cancer-busting diet. We need to keep things in perspective, and not suggest rigid avoidance. There is simply no evidence to say that having a ham sandwich will give you cancer, and most sensible people, including experts such as the Food Standards Agency, acknowledge this.
I certainly won’t stop having a ham sandwich, the occasional glass of wine or a takeaway. After 30 years as a doctor spent treating cancer patients it is clear to me that cancer and the risk factors associated with it are far more complex than some of the simplified media coverage often suggests.
