When compared with regular meat eaters, those who consume smaller amounts meat have a 2% lower risk of cancer.
Meanwhile pescatarians – who eat fish and vegetables – have a 10% reduced risk and vegetarians are 14% less likely to develop cancer.
The 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.
The participants, aged between 40 and 70, were asked about their dietary habits including how regularly they ate meat or fish.
More than half (52%) ate meat more than five times per week, 44% of participants ate meat five or less times per week, 2% ate fish but not meat, and 2% were vegetarian or vegan.
Researchers then tracked their health records for up to 11 years to see whether or not they went on to develop cancer.
During this time 55,000 cases of cancer were identified among the participants.
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.”
Healthy diet ‘great way’ to lower risk of cancer
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.”