09 April 2010
Do you still need your five-a-day?
Eating fruit and vegetables may only have a modest effect on your risk of developing cancer, according to new research published in the Journal of the National Cancer Institute.
The study comes from the European Prospective Investigation into Cancer and Nutrition (EPIC), which looked at over half a million people from 10 countries across Europe to see whether diet has an effect on cancer risk. The current analysis from the EPIC study was carried out specifically to look at the link between fruit and vegetable intake and overall cancer risk, and included just under half a million people.
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Dr Annabel Bentley, Assistant Medical Director, Bupa |
Don't ditch your five-a-day just yet. Although fruit and vegetables may not lower cancer risk by much, they do have a protective effect against heart disease and stroke. 
The study participants filled out a questionnaire at the start of the study about their diet over the past year. Some were also asked to report what they had eaten in the last day to ensure the results were accurate. For the current analysis, the researchers looked at the amount of fruit (not including fruit juices) and vegetables (not including potatoes, pulses or vegetable juices) that the people in the study ate. The researchers then followed up the participants for an average of nearly nine years and found out whether they had developed cancer by contacting them or their next of kin, and searching through cancer and mortality registries in each country.
The men and women in the study were also asked various questions about their lifestyle, such as whether they smoked, their alcohol intake and the amount of physical activity they did. People who ate more fruit and vegetables tended to have other healthy lifestyle factors too, which are known to be related to reduced cancer risk, such as not smoking. The researchers took these factors into account when analysing their results, so that they only looked at the effect of fruit and vegetable intake.
Over the study period about 30,000 people developed cancer. The researchers found that the more fruit and vegetables people ate, the less likely they were to develop cancer. However, this reduction in risk was small. For every 200g increase (about two and a half portions) in fruit and vegetables eaten per day, the overall risk of cancer was reduced by three percent. The effect of fruit was found to be weaker than that of vegetables. Based on these results, the researchers calculated that in practice, this would mean that if everyone in the study ate 150g more fruit and vegetables a day (or nearly two extra portions), one in every 38 cancers in men and one in every 43 cancers in women would be prevented.
As the study only looked at overall cancer risk and not specific types of cancer, it couldn't show whether fruit and vegetable intake may have a greater effect on some cancers more than others. It also didn't investigate possible differences in specific types of fruit and vegetables. For instance there is evidence that a chemical called lycopene found in tomatoes can reduce risk of prostate cancer.
Commenting on the study, Bupa's Assistant Medical Director Dr Annabel Bentley said: "This study adds to our understanding of cancer risk. But don't ditch your five-a-day just yet. Although fruit and vegetables may not lower cancer risk by much, they do have a protective effect against heart disease and stroke."
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Related information
Read the study
Boffeta P, Couto E, Wichmann J, et al. Fruit and vegetable intake and overall cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC). J Natl Cancer Inst 2010; 102:1-9. doi: 10.1093/jnci/djq072
