Vegetarian diet can slash the risk of five cancers by as much as 30% – study

A vegetarian diet can slash the risk of five cancers by as much as 30%, research suggests.

The largest ever study of its kind found vegetarians have a 21% lower risk of pancreatic cancer and a 9% lower risk of breast cancer compared with meat eaters.

They also have a 12% reduced risk of prostate cancer, 28% lower risk of kidney cancer and 31% lower risk of multiple myeloma.

However, researchers at the University of Oxford found vegetarians have nearly double the risk of the most common type of cancer of the oesophagus compared with meat eaters.

This might be due to vegetarians missing out on some key nutrients, the team suggested.

It is already known that eating processed meat such as ham, bacon and salami is linked to an increased risk of bowel cancer, and possibly stomach cancer.

Red meat such as beef, pork and lamb also increases the risk, while white meat, such as chicken and turkey, has not shown a link.

Experts behind the new study, published in the British Journal of Cancer, said more work was needed on whether it is overall meat consumption that is problematic when it comes to cancer, or whether something specific in vegetarian diets lowers cancer risk.

The new research included data from various studies across the world, with most people coming from the UK and US.

Some 1.64 million meat eaters were included, alongside 57,016 poultry eaters (no red meat), 42,910 people who ate fish and no meat (pescatarians), 63,147 vegetarians and 8,849 vegans.

Led by researchers at Oxford Population Health, which is part of Oxford University, and funded by the World Cancer Research Fund, the study investigated 17 different cancers, including those of the gastrointestinal tract, lung, reproductive system, urinary tract, and blood cancer.

Food intake, generally over the previous 12 months or a “typical diet”, was assessed using food questionnaires. Factors that may influence the results, such as body mass index, were taken into account.

When looking at vegans, researchers found they had a significantly higher risk of bowel cancer when compared with meat eaters.

They said this may be due to a low average intake of calcium compared with other people (590 milligrams per day compared to a recommendation of 700 milligrams per day), and low intakes of other nutrients.

Cancer Research UK has already found that calcium lowers bowel cancer risk, with a large glass of milk a day linked to a 17% reduction.

However, the Oxford team said more research was needed in this area owing to the fact only 93 bowel cancers were found in the vegan group.

For the other cancers studied, there was no evidence that risk in vegans differed from meat eaters, and for some less common cancers there were too few vegan cases to analyse.

Vegetarians also did not have a lower risk of bowel cancer, compared with meat eaters, which the researchers said was “inconsistent” with the knowledge that processed and red meat increases the risk.

They said this was likely because processed meat intake in the meat eating group was moderately low.

Aurora Perez Cornago, principal investigator of the study, said: “Vegetarians typically consume more fruit, vegetables and fibre than meat eaters and no processed meat, which may contribute to lower risks of some cancers.”

She added: “The higher risk of oesophageal squamous cell carcinoma in vegetarians and bowel cancer in vegans may relate to lower intakes of certain nutrients more abundant in animal foods.

“Additional research is needed to understand what is driving the differences in cancer risk found in our study.”

Tim Key, emeritus professor of epidemiology at Oxford Population Health and co-investigator of the study, said there are around three million vegetarians in the UK and interest “in vegetarianism growing in many parts of the world”.

He said that, although it is true that vegetarians do eat more fibre and more fruit and vegetables, the differences in the study between the two groups were “not very big” and may not explain the findings.

He said “my feeling is the differences are more likely to be related to meat itself than to simply vegetarians eating more healthy foods”.

“But that’s sort of an opinion which we haven’t looked at directly,” he added.

Dr Helen Croker, assistant director of research and policy at the World Cancer Research Fund International, said: “To increase your overall protection from cancer, our advice is to build meals around wholegrains, pulses, fruit and vegetables, and avoid processed meat and limit red meat.”

Amy Hirst, health information manager at Cancer Research UK, said the “high-quality study” offers some interesting insights, but the findings were not strong enough to draw definitive conclusions.

“More research in larger, more diverse populations is needed to better understand these patterns and what’s causing them.

“When it comes to reducing cancer risk, keeping a healthy, balanced diet overall matters more than individual foods.

“Aim for plenty of fruit, vegetables, wholegrains and sources of protein – as well as cutting down on processed and red meat, alcohol, and foods high in fat, salt and sugar.”