More than 61,000 people were monitored over 12 years by Cancer Research U.K. scientists from Oxford, who found that vegetarians were 12% less likely to develop cancer than people who ate meat.

The risk was almost halved for cancers of the blood including leukaemia, multiple myeloma and non-Hodgkin lymphoma, where vegetarians' risk was 45% lower than meat eaters.

People who ate fish but no meat also had a "significantly lower" chance of developing many cancers, according to the research published in the British Journal of Cancer.

The group which was studied included 32,403 meat eaters, 8,562 people who ate fish but no meat (pescetarians) and 20,601 vegetarians who ate neither.

During the study, 3,350 (5.4%) of the participants were diagnosed with cancer.

Some 2,204 (6.8%) of the meat eaters were diagnosed with a form of cancer, compared with 317 (3.7%) of pescetarians and 829 (4%) of vegetarians.

Professor Tim Key, the study's author from the Cancer Research U.K. 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 and found the differences in risks between vegetarians and meat eaters were independent of other lifestyle factors including smoking, alcohol intake and obesity, which also affect the risk of developing cancer.

Sara Hiom, director of health information at Cancer Research U.K., 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 U.K.'s advice that people should eat a healthy, balanced diet high in fiber, fruit and vegetables and low in saturated fat, salt and red and processed meat.

"It's understandable that there's a link between what you eat and cancers of the digestive system. But we are surprised to see an association between leukaemia, non-Hodgkin lymphoma and multiple myeloma, and more research is needed to understand the mechanisms involved."

Previous studies have suggested vegetarians have a reduced risk of bowel cancer.

This study, which pools data from the Oxford Vegetarian Study and the EPIC-Oxford study, "did not observe any significant difference in the incidence of colorectal cancer between the dietary groups."

The authors suggested more research was needed into the possible relationship between meat consumption and colorectal cancer.

Stomach cancer was said to be significantly lower in the vegetarian group which had around a third of the risk of meat eaters. The group that ate fish also had a much lower risk than the meat eaters.

The relative risk of cervical cancer in vegetarians and fish eaters was double that of the meat eaters, but the study's authors said the results were based on only 50 cases in total and may have been influenced by other factors including differences in women's attendance for screening.

From the July 6, 2009, Prepared Foods E-dition