Fruits and vegetables and cancer prevention

I can imagine people who have read today’s media coverage about fruits and vegetables and cancer risk might be feeling confused. It is all too easy when organisations like World Cancer Research Fund (WCRF) say it is important to eat plenty of fruits and vegetables for cancer prevention and then newspapers like the Guardian report that “Fruit and vegetables do not reduce overall cancer risk”.

We have responded to today’s coverage with a statement saying fruits and vegetables are still important for cancer prevention.

But why does the picture on fruits and vegetables and cancer seem so confusing?

Let’s start with some facts most scientists in this area do agree on:

  • Fruits and vegetables probably do reduce risk of cancer, although the evidence is not strong enough for us to be certain
  • Any direct protective effect seems to be limited to certain types of cancer such as cancers of the stomachoesophagus, and mouth, pharynx and larynx
  • Because fruits and vegetables are only linked to risk of certain types of cancer, the percentage of overall cancer cases that could be prevented is quite small
  • But because there are so many cases of cancer diagnosed every year, this still means thousands of cases could be prevented each year if everyone ate more fruits and vegetables
  • Even aside from any direct effect of fruits and vegetables on cancer risk, they still play an important role in keeping us healthy, particularly as people who eat plenty of them are still less likely to be overweight
  • This is important because there is convincing evidence that excess body fat increases risk of six types of cancer, including bowel cancer and breast cancer

None of these facts is controversial.

Essentially, these are the findings of WCRF’s 2007 landmark cancer prevention report. They also reflect the findings of a big study on fruits and vegetables and cancer that was published earlier this year, which suggested about 7,000 cases of cancer a year could be prevented in the UK if we all ate an extra two portions a day.

What’s more, these facts are consistent with the findings of this latest review.

So why have studies with similar findings led to such dramatically different headlines?

Well, it’s all a question of emphasis. Essentially, it boils down to whether your glass is half full or half empty.

Some people choose to focus on the fact that we are not certain that fruits and vegetables reduce cancer risk and that the overall proportion of cancer cases they could probably prevent is small.

And this is true.

But at World Cancer Research Fund, we think it is worth encouraging people to eat plenty of fruits and vegetables because the evidence shows they probably reduce cancer risk.

And while the proportion of cancers that could be prevented may be small, this still adds up to thousands of cases in the UK every year. There is also the added benefit that eating plenty of fruits and vegetables is a good way of maintaining a healthy weight.

Also, there are other health benefits of eating fruits and vegetables, including reducing risk of heart disease.

We are confident in our Recommendation to eat at least five portions of fruits and vegetables as part of a plant-based diet because this is the judgement of an independent panel of 21 world-renowned scientists who made recommendations after looking at all the scientific evidence. This means the people who follow our 10 Recommendations for Cancer Prevention can be confident they are following the best advice available.

So despite the news stories that say the opposite, people who are concerned about cancer should still eat plenty of fruits and vegetables as part of a wider healthy lifestyle.

The media coverage of this review has been unhelpful. It gives the impression it has found something dramatically new, which it hasn’t.

And it is also likely to reinforce the impression that scientists are always changing their minds or cannot agree about cancer risk. Actually, the advice on how to reduce your risk has not changed that much over the last 10 years and in many areas the evidence behind our Recommendations has become stronger.

We asked YouGov to carry out a survey on this and it found that 27 per cent of people said that, because scientists are always changing their minds, the best approach is to ignore health advice and just eat what you want.

This is why media coverage matters and in fact World Cancer Research Fund’s Policy Report identified the media as one of the nine groups in society that can make changes that can help prevent cancer.