People who do not eat meat are at greater risk of broken bones, particularly their hips, according to the largest study of this risk. The result can emerge from a lack of calcium and protein in their diet, as well as from the fact that they appear to be thinner and thus have less flesh to cushion a fall.

Several previous studies have shown that vegetarians have weaker bones than meat-eaters, but it was unknown if this would have a direct impact on their risk of fractures.

The new research took advantage of a long-term study, EPIC-Oxford, initially set up to investigate whether diet affects the risk of cancer by tracking the health of some 65,000 people in the United Kingdom from 1993 onwards. The research documented a normal diet of people and monitored their health via hospital records.

By 2010, vegans had fractured hips at more than double the pace of meat-eaters, whereas vegetarians and fish eaters were at a lower risk of around 25%. Vegans - but not vegetarians and pescetarians - were often at greater risk of breaking other bones.

The potential risk to vegans was comparatively minimal, leading to an additional 20 broken bones per 1,000 people over 10 years of age. But the fracture rate is likely to be higher in elderly people who break their hips more frequently than not, as the average age of participants at the beginning was 45, says researcher Tammy Tong at Oxford University.

When people's diets were measured, meat-eaters absorbed more calcium and protein. Calcium is an important component of bones, and proteins can help in the absorption of calcium from food.

"Unless they are actively supplementing, it's quite unlikely that vegans will have a sufficient intake of calcium just from the diet," says Tong.

But people who consume a vegan diet today may likely have higher calcium levels. There was less fortification of plant milk in the 1990s, the study noted.

Heather Russell, a dietitian at the Vegan Society in the United Kingdom, emphasized that you can look after your bones on a well-planned vegan diet, but people need the information to make healthy choices.

Studying the same group of people has previously shown that being vegetarian is associated with a 10% lower incidence of cancer after 15 years and a 20% lower prevalence of heart disease - but also a 20% higher chance of stroke.