OXFORD, UNITED KINGDOM — A study published in the British Journal of Cancer indicates women who always or mostly eat organic foods have the same likelihood of developing cancer as women who eat conventionally produced foods. The study was conducted by researchers at University of Oxford and included a survey of approximately 600,000 women aged 50 or over.

Kathryn Bradbury and colleagues in Oxford’s Cancer Epidemiology Unit found no evidence that regularly eating a diet that was grown free from pesticides reduced a woman’s overall risk of cancer. They looked at how many of the women developed 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 found no difference in overall cancer risk when comparing 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 the results may be partly due to chance and other factors, according to the researchers.

“In this large study of middle-aged women in the U.K. we found no evidence that a woman’s overall cancer risk was decreased if she generally ate organic food,” said Tim Key, a professor at the University of Oxford and the author of the study.

Claire Knight, health information manager for Cancer Research U.K., 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 9% of cancer cases in the U.K. may be linked to dietary factors, of which almost 5% 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.”

The study is a part of the U.K.’s Million Women Study, which is a national study of women’s health that involves more than 1 million U.K. women aged 50 and over. It is a collaborative project between Cancer Research U.K. and the National Health Service, with additional funding from the Medical Research Council and the Health and Safety Executive, which aims to answer questions about the factors affecting women’s health in this age group.