A low or meat free diet could help reduce the risk of cancer, a study of almost half a million people found.
Eating meat five times or less per week is associated with a lower overall cancer risk, according to a study published in the open access journal BMC Medicine.
The University of Oxford study, published in the journal BMC Medicine and co-funded by World Cancer Research Fund and Cancer Research UK, saw researchers from the University of Oxford analysing data collected from 472,377 British adults taking part in the UK Biobank study between 2006 and 2010.
Participants, who were aged between 40 and 70 years, reported how frequently they ate meat and fish and the researchers calculated the incidence of new cancers that developed over an average period of 11 years using health records.
Compared with regular meat eaters, those who consume small amounts of meat have a 2 per cent lower risk of cancer, while pescatarians – who eat fish and vegetables – have a 10 per cent reduced risk and vegetarians are 14 per cent less likely to develop cancer.
Experts said that people who do not eat a lot of meat had a 9 per cent lower risk of developing bowel cancer compared with “regular” meat eaters.
And vegetarian women were 18 per cent less likely to develop postmenopausal breast cancer compared with those who ate a regular amount of meat.
The researchers also found that the risk of prostate cancer was 20 per cent lower among men who ate fish but not meat and 31% lower among men who followed a vegetarian diet.
Lead researcher Cody Watling, from Oxford Population Health’s Cancer Epidemiology Unit, said: “Previous evidence has suggested that vegetarians and pescatarians may have a lower risk of developing cancer, however the evidence for a lower risk of developing specific types of cancer has been inconclusive.
“Being overweight after menopause is known to increase the risk of breast cancer and so the reduced risk of postmenopausal breast cancer in vegetarian women, due to lower BMI, was unsurprising – but we were surprised by the substantially lower risk of prostate cancer in vegetarians.”
Dr Giota Mitrou, director of research and innovation at World Cancer Research Fund International, said: “One in two of us will get cancer in our lifetime and while there are lots of things about cancer we cannot control, we know that currently 40% of cancer cases could be prevented through lifestyle changes including diet, weight and physical activity.
“The results of this large, British study suggest that specific dietary behaviours such as low meat, vegetarian or pescatarian diets can have an impact on reducing the risk of certain cancers: in this case bowel, breast and prostate.”
Dr Julie Sharp, head of health and patient information at Cancer Research UK, said: “Maintaining a healthy diet is a great way to lower your risk of cancer and eating less processed meat reduces your risk of bowel cancer, specifically.
“But more research is needed to understand the link between red and processed meat and other cancer types.
“Having some bacon or ham every now and then won’t do much harm. 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.
“It’s more important to have a balanced diet with lots of fruit, vegetables and high fibre foods, like wholegrains and pulses, and low in processed and red meat and foods high in salt, sugar and fat.”
The impact was particularly significant for certain cancers.
The authors found that those who ate the least meat had a 9 per cent lower risk of colorectal cancer, compared to those with the meat-heavy diet.
They also found that the risk of prostate cancer was 20 per cent lower among men who ate fish but not meat and 31 per cent lower among men who followed a vegetarian diet, compared to those who ate meat more than five times per week.
Post-menopausal women who followed a vegetarian diet had an 18 per cent lower risk of breast cancer. However, the findings suggest that this was due to vegetarian women tending to have a lower body mass index (BMI) than women who ate meat.
The researchers caution that the observational nature of their study does not allow for conclusions about a causal relationship between diet and cancer risk. Additionally, as the data was collected at a single time-point, rather than over a continuous period of time, it may not be representative of participants’ lifetime diets.
The authors suggest that future research could investigate the associations between diets containing little or no meat and the risk of individual cancers in larger populations with longer follow-up periods.