Vegetarians and vegans are much less likely to develop a range of cancers, a detailed diet study has discovered.
The research study looking at 80,000 people in North America has found that vegetarians had a 12% lower risk of developing cancer than meat eaters.
A vegan diet is understood to reduce the risk of cancer by about a quarter.
A vegetarian diet was also credited with reducing the risk of specific cancers even further.
Being vegetarian reduces the risk of stomach cancer by up to 45% as well as reducing the risk of lymphomas by 25%.
The study’s lead author, Gary Fraser, said this is the first study with strong information to report on the association between various vegetarian diets and the risk of less common cancers.
Mr Fraser said the study also offered solid evidence confirming previous studies that vegans have lower risks of the common breast and prostate cancers.
The risk of colorectal cancer was reduced by approximately 20% with a vegetarian diet, Mr Fraser added.
“This is all relatively unique information and possibly the most robust that’s out there concerning cancers such as stomach and lymphoma,” Fraser said. “It may also be pointing the finger at several other cancers, such as lung, ovary, and pancreas, where the evidence from this study was suggestive of lower risk in vegetarians, but did not quite reach the necessary standard to say more.”
Fraser said other cancers, such as uterine, myeloma, myeloid leukaemias, or those of the nervous system, gave no hint of protection from diet.
The study was published this month in the American Journal of Clinical Nutrition, and around half of the 80,000 people who took part were vegetarians.
Researchers followed nearly 80,000 members of the Seventh-day Adventist Church in North America, who already have a much lower risk of cancer compared to the general population in the United States.
“Many of those non-vegetarian Adventist people in this study were still very health-conscious people, so in some ways, it’s amazing that we found anything at all,” Mr Fraser added.
While the new study found overall increased benefits for vegans compared to other vegetarian diets, one exception was that a pescatarian diet was found to have less risk of colorectal cancers compared to other vegetarian diets.
Vegetarians who ate dairy and eggs also had some protection against blood cancers, the study added.
Vegetarians were also found to be leaner, smoked and drank less, exercised slightly more and were more likely to have a university degree.
Dr Tilman Kuhn of Queen’s University Belfast, who was not involved in the study, told the Times that the reduced risk for vegetarians of developing gastrointestinal cancers was unsurprising.
He said: “Diets low in meat and high in fibre, via wholegrains, fruits and vegetables, have been shown to be associated with lower risks of these cancers in other populations.”
“The results on lymphoma are surprising and new, as underlying mechanisms are not known,” he added. “The study is one of the few studies worldwide with meaningful numbers of vegans and vegetarians under long-term observation. Comparing long-term diets is a powerful research model.”
