Eating more fruit and vegetables has only a modest effect on protecting against cancer, a study into the link between diet and disease has found.
The study of 500,000 Europeans joins a growing body of evidence undermining the high hopes that pushing “five-a-day” might slash Western cancer rates.
The international team of researchers estimates only around 2.5% of cancers could be averted by increasing intake.
But experts stress eating fruit and vegetables is still key to good health.
In 1990, the World Health Organization recommended that everyone consume at least five portions of fruit and vegetables a day to prevent cancer and other chronic diseases.
The advice has formed a central plank of public health campaigns in many developed countries. It has been promoted in the UK since 2003 and in the US for nearly two decades.
But research has failed to substantiate the suggestion that as many as 50% of cancers could be prevented by boosting the public’s consumption of fruit and vegetables.
This latest study, which analysed recruits from 10 countries to the highly-regarded European Prospective Investigation into Cancer and Nutrition, confirms that the association between fruit and vegetable intake and reduced cancer risk is indeed weak.
The team, led by researchers from the Mount Sinai School of Medicine, in New York, took into account lifestyle factors such as smoking and exercise when drawing their conclusions.
But writing in the Journal of the National Cancer Institute, they said they could not rule out that even the small reduction in cancer risk seen was down to the fact that the kind of people who ate more fruit and vegetables lived healthier lives in many other respects too.
Broccoli not biscuits
In the best case scenario, an extra two portions of fruit and vegetables each day could prevent 2.6% of cancers in men and 2.3% of cases in women, the study concluded.
Vegetables, which tend to be richer in nutrients, appeared to be more beneficial than fruits, while heavy drinkers seemed to gain the most from a higher intake of both when it came to protection from cancers caused by alcohol and smoking.