“The results … suggest that specific dietary behaviours such as low meat [and] vegetarian or pescatarian diets can have an impact on reducing the risk of certain cancers; in this case bowel, breast and prostate,” said Dr Giota Mitrou, director of research and innovation at World Cancer Research Fund International (WCRF), which co-funded the study with Cancer Research UK.
The results confirm WCRF’s longstanding advice that people should limit their intake of red and processed meat and eat more wholegrains, vegetables, fruit and pulses, she added.
The Oxford study authors said: “The lower risk of colorectal [bowel] cancer in low meat-eaters is consistent with previous evidence suggesting an adverse impact of meat intake. Vegetarian women’s lower risk of postmenopausal breast cancer is likely to be “largely” explained by their lower BMI.
“It is not clear whether the other differences observed for all cancers and for prostate cancer reflect any causal relationship or are due to other factors.”
While the researchers found that “being a low meat-eater, pescatarian or vegetarian was associated with a lower risk of all cancer”, they added that this “may be a result of dietary factors and/or non-dietary differences in lifestyle, such as smoking”. Their results are published on Thursday in the journal BMC Medicine.
Richard McIlwain, chief executive of the Vegetarian Society, said: “This study adds to a growing body of research reinforcing the positive, protective effects of a vegetarian diet.
“With cancer now affecting one in every two of us across the country, adopting a healthy vegetarian diet can clearly play a role in preventing this disease. Indeed, evidence from previous surveys suggests a balanced vegetarian diet can also reduce the risk of heart disease and diabetes, in addition to cancers.”
Watling and his colleagues are undertaking further research among vegetarians, pescatarians and vegans to examine more closely the relationship between diet and cancer risk.
Between 5% and 7% of Britons are thought to be vegetarian and 2-3% follow a vegan diet, according to surveys by YouGov.
Dr Julie Sharp, Cancer Research UK’s head of health and patient information, said that while reducing intake of processed meat has been proven to reduce the risk of bowel cancer “having some bacon or ham every now and then won’t do much harm”, adding: “If you are having a lot of meat a lot of the time then cutting down is a good idea, but a vegetarian diet doesn’t always mean someone is eating healthily.”