Compared with people who ate meat, vegans with lower calcium and protein intakes (on average) had a 43 per cent higher risk of fractures anywhere in the body, researchers have warned.
According to the findings, published in the journal BMC Medicine, vegetarians and people who ate fish but not meat had a higher risk of hip fractures, compared to people who ate meat.
However, the risk of fractures was partly reduced once body mass index (BMI), dietary calcium and dietary protein intake were taken into account.
"We found that vegans had a higher risk of total fractures which resulted in close to 20 more cases per 1000 people over a 10-year period compared to people who ate meat," said study author Tammy Tong from the University of Oxford in the UK.
"The biggest differences were for hip fractures, where the risk in vegans was 2.3 times higher than in people who ate meat, equivalent to 15 more cases per 1000 people over 10 years," Tong added.
For the findings, the research team, analysed data from nearly 55,000 people in the EPIC-Oxford study, a prospective cohort of men and women living in the UK, who were recruited between 1993 and 2001, many of whom do not eat meat.
Out of the 54,898 participants included in the present study, 29,380 ate meat, 8,037 ate fish but not meat, 15,499 were vegetarians, and 1,982 were vegans when they were recruited.
Their eating habits were assessed initially at recruitment, then again in 2010. Participants were followed continuously for 18 years on average, until 2016 for the occurrence of fractures.
During the time of the study, 3,941 fractures occurred in total, including 566 arm, 889 wrist, 945 hip, 366 leg, 520 ankle and 467 fractures at other main sites, defined as the clavicle, ribs and vertebrae.
In addition to a higher risk of hip fractures in vegans, vegetarians and pescetarians (those who eat seafood but not meat) than the meat eaters, vegans also had a higher risk of leg fractures and other main site fractures.
The authors observed no significant differences in risks between diet groups for arm, wrist or ankle fractures once BMI was taken into account.
The researchers found that the differences in risk of total and site-specific fractures was partly reduced once BMI, dietary calcium and dietary protein intake had been taken into account.
"This study showed that vegans, who on average had lower BMI as well as lower intakes of calcium and protein than meat eaters, had higher risks of fractures at several sites," the authors wrote.