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 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, more research is needed to understand the mechanisms involved."

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