Vegetarians and fish-eaters may be at slightly lower risk of cancer than meat-eaters, according to a new study.
Studies of how diet affects cancer risk have been notoriously inconclusive. Some have shown that more meat consumption leads to a higher risk of bowel cancers - but other studies have not. About the only factors known to increase the risk are obesity and alcohol consumption, says Oxford University epidemiology professor Tim Key.
"When you come to, does it matter what you eat, apart from alcohol and how fat you are? It's been very hard to reach firm conclusions."
In the latest study, Key and his colleagues looked at more than 60 thousand people over the course of 12 years and found that vegetarians had about a 12 percent lower risk of cancer. The risk for people who ate fish - but not other meat - was reduced by about 18 percent.
To put that in perspective, Key says about 33 out of 100 people in the United States will develop cancer in their lifetimes. Reducing risk by 12 percent means that 29 vegetarians will develop cancer.
"So, it's a reduction. It's not a massive reduction," he says.
"The vegetarian diet, though, is a healthy diet, if - I should say if - done correctly," says Keri Gans, a registered dietitian and a spokeswoman for the American Dietetic Association.
She says other research clearly shows a vegetarian diet is healthier for your heart. But she stresses that vegetarians need to be sure they get enough of certain nutrients that non-vegetarians get regularly, such as protein and calcium.
Key's study was published in the British Journal of Cancer.