In a study of more than 61,000 people, Cancer Research UK scientists from Oxford followed meat eaters and vegetarians for over 12 years, during which 3,350 of the participants were diagnosed with cancer.
They found that the risk of being diagnosed with cancers of the stomach, bladder and blood* was lower in vegetarians than in meat eaters.
The most striking difference was in cancers of the blood including leukaemia, multiple myeloma and non-Hodgkin lymphoma. The risk of these diseases was 45 per cent lower in vegetarians than in meat eaters.
Professor Tim Key, study author from the Cancer Research UK Epidemiology Unit at Oxford University, said: "Our large study looking at cancer risk in vegetarians found the likelihood of people developing some cancers is lower among vegetarians than among people who eat meat. In particular vegetarians were much less likely to develop cancers of the blood which include leukaemia and non-Hodgkin lymphoma. More research is needed to substantiate these results and to look for reasons for the differences."
The study looked at 20 different types of cancers. The differences in risks between vegetarians and meat eaters were independent of other lifestyle behaviours including smoking, alcohol intake and obesity which also affect the chance of developing cancer.
Sara Hiom, director of health information at Cancer Research UK, said: "These interesting results add to the evidence that what we eat affects our chances of developing cancer. We know that eating a lot of red and processed meat increases the risk of stomach cancer. But the links between diet and cancer risk are complex and more research is needed to see how big a part diet plays and which specific dietary factors are most important.
"The relatively low number of vegetarians who developed cancer in this study supports Cancer Research UK's advice that people should eat a healthy, balanced diet high in fibre, fruit and vegetables and low in saturated fat, salt and red and processed meat.
"It's understandable that what you eat can be linked to cancers of the digestive system, but more surprising to see an association between diet and leukaemia, non-Hodgkin lymphoma or multiple myeloma. More research is needed to understand the mechanisms behind this."
Notes
*Blood cancers include non-Hodgkin lymphoma, multiple myeloma and leukaemia
**The results include data from two previous studies - Oxford Vegetarian Study and EPIC-Oxford
Source
Cancer Research UK