Organic food doesn’t lower overall cancer risk

Cancer Research UK

Women who always or mostly eat organic foods are no less likely to develop cancer than women who eat a more conventional diet, according to a study* published in the British Journal of Cancer.“In this large study of middle-aged women in the UK we found no evidence that a woman’s overall cancer risk was decreased if she generally ate organic food." - Prof Tim Key, study author

Cancer Research UK scientists from the University of Oxford found no evidence that regularly eating a diet that was grown free from pesticides reduced a woman’s overall risk of cancer.

The researchers asked around 600,000 women aged 50 or over, who were part of the Million Women Study**, about whether they ate organic foods, and tracked the development of 16 of the most common types of cancer in a nine year period following the survey. Around 50,000 women developed cancer in this period.

The scientists’ analysis found no difference in overall cancer risk when comparing the 180,000 women who reported never eating organic food with around 45,000 women who reported usually or always eating organically grown food.

When looking at the results for 16 individual types of cancer they found a small increase in risk for breast cancer but a reduction in the risk for non-Hodgkin lymphoma in women who mostly ate organic food, although these results could be partly due to chance and other factors.

Professor Tim Key, a Cancer Research UK epidemiologist based at the University of Oxford and one of the study authors, said: “In this large study of middle-aged women in the UK we found no evidence that a woman’s overall cancer risk was decreased if she generally ate organic food. More research is needed to follow-up our findings of a possible reduction in risk for non-Hodgkin lymphoma.”

Pesticides are widely used in agriculture and there are concerns that they could increase the risk of cancer but so far the evidence has not been strong enough to give us any clear answers***. Conventionally grown fruit and vegetables sometimes contain very small amounts of pesticides but there is no evidence that these small amounts increase the risk of cancer in people who eat them.

Dr Claire Knight, Cancer Research UK’s health information manager, said: “This study adds to the evidence that eating organically grown food doesn’t lower your overall cancer risk. But if you’re anxious about pesticide residues on fruit and vegetables, it’s a good idea to wash them before eating.

“Scientists have estimated that over nine per cent of cancer cases in the UK may be linked to dietary factors, of which almost five per cent are linked to not eating enough fruit and vegetables. So eating a well-balanced diet which is high in fruit and vegetables – whether conventionally grown or not – can help reduce your cancer risk.”

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References

*Bradbury, KE et al. Organic food consumption and the incidence of cancer in a large prospective study of women in the UK (2014) British Journal of Cancer. doi:10.1038/bjc.2014.148

Notes to Editor

**The study, funded by Cancer Research UK and the Medical Research Council, is following the health of than one million white women, almost 6,000 south Asian women and almost 5,000 black women in England. Women were recruited between 1996 and 2001, when they were aged 50-64 years, and filled in questionnaires asking about their lifestyle and other risk factors.

***People exposed to higher levels of pesticides as part of their job – for example in industry or in farming - may be at slightly higher risk of certain cancers, particularly leukaemias and lymphomas. The International Agency for Research into Cancer (IARC) have looked at the evidence and said that regularly spraying pesticides as part of your job “probably” slightly increases the risk of cancer. But for individual pesticides, the evidence was either too weak to come to a conclusion, or only strong enough to suggest a “possible” effect. Some potentially dangerous pesticides such as DDT and lindane have been used in the past but are now banned.