'Five-a-day' has limited impact on cancer risk

Posted on: 07 April 2010 by Mark O'haire

Eating fruit and vegetables to ward off cancer has a "modest" impact on reducing the risk, according to a new Europe-wide study.

Research on almost 500,000 people found eating five portions of fruit and vegetables a day had little effect on cancer risk, as did eating more or fewer portions.

Data was analysed from 23 centres in 10 European countries part of the European Prospective Investigation into Cancer and Nutrition.

Experts said that while there is evidence of a "small" protective effect of fruit and vegetables, the chance a reduced risk could be caused by something else cannot be ruled out.

In the study daily fruit and vegetable consumption was combined and adjusted to incorporate other factors likely to influence the results such as smoking, alcohol, obesity and exercise. Factors specific to women such as if they had ever taken the Pill or hormone replacement therapy were also analysed. 

The results showed that regardless of which group people were in, if everyone ate an extra 200g of fruit and vegetables a day, the overall reduced risk of cancer was 3 per cent.

Eating an extra 100g of vegetables a day decreased the risk by about 2 per cent while an extra 100g of fruit a day reduced the risk by about 1 per cent.

The link between eating a large amount of vegetables and reduced cancer risk only applied to women, the study found.

And while heavy drinkers had a reduced risk from eating lots of fruit and vegetables, this reduction only applied to cancers caused by alcohol or smoking.

Further analysis showed that if everyone in the sample ate an extra 150g a day of fruit and vegetables, 2.6 per cent of cancers in men and 2.3 per cent of cancers in women could be avoided.

The research, published in the Journal of the National Cancer Institute concluded that the link between reduced rick of cancer and fruit and vegetables was "very weak".

Experts have said the despite the findings it is still important to maintain a healthy lifestyle.

Dr Rachel Thompson, science programme manager for the World Cancer Research Fund, said: "This study suggests that if we all ate an extra two portions of fruits and vegetables a day (about 150g), about 2.5 per cent of cancers could be prevented.

"Given the fact that there are many types of cancer where there is no evidence eating fruits and vegetables affects risk, it is not surprising that the overall percentage is quite low.

"But for the UK, this works out as about 7,000 cases a year, which is a significant number.

"If you look at specific types of cancer, including mouth, pharynx and larynx, stomach and oesophagus, the evidence shows that eating plenty of fruits and vegetables probably reduces risk.

"Even if fruits and vegetables did not directly reduce risk, it would still be a good idea to eat them because people who eat plenty of fruits and vegetables are less likely to become overweight.

"Scientists now say that, after not smoking, maintaining a healthy weight is the most important thing you can do for cancer prevention."

In the UK, centres at Cambridge and Oxford were included in the study, which looked at cancer risk between 1992 and 2000.

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