Both women and men who follow a vegetarian diet faced a higher risk of hip fracture than regular meat-eaters, a study in the journal BMC Medicine found.
The research by the University of Leeds suggested that an understanding of diet quality and the balance of key nutrients could help to reduce this risk and improve bone health.
Hip fractures cost the NHS an estimated £2 billion each year. They were a "growing problem in an ageing society and can trigger debilitating health conditions and a loss of quality of life", according to study lead James Webster, a doctoral researcher at the university's School of Food Science and Nutrition.
Although it had already been recognised that vegetarian women had an "elevated" risk of hip fracture, the reasons for this remained unclear, highlighted the authors. Moreover, studies looking at the impact of a vegetarian diet on men had been "small scale and inconclusive", they added.
Data from UK Biobank
The researchers set out to investigate the risk of hip fracture in occasional meat-eaters, pescatarians, and vegetarians, compared with regular meat-eaters, and to explore the role of potential mediators of any observed risk differences.
The observational study analysed data from the UK Biobank of 413,914 men and women who were either regular meat eaters who ate meat five or more times a week; occasional meat eaters consuming meat fewer than five times week; pescatarians eating fish but not meat; or vegetarians who consumed dairy foods but not fish or meat.
At recruitment, on average, pescatarians and vegetarians were younger than meat-eaters, though time to hip fracture and age at hip fracture were similar across the diet groups.
Data on the individuals was linked to their hospital records and cases of hip fracture were recorded in the follow-up period to 2021. Over a median follow-up time of 12.5 years, 3503 hip fractures were observed, which corresponded to 0.8% of the cohort.
The researchers found that after adjustment for confounders, vegetarians (HR 1.50) - but not occasional meat-eaters (HR 0.99) or pescatarians (HR 1.08) - had a greater risk of hip fracture than regular meat-eaters.
"Both men and women who follow a vegetarian diet face a 50% greater risk of a hip fracture compared to people who regularly eat meat," underlined the authors. Although the overall risk of having a hip fracture was low, the relative risk between vegetarians and regular meat eaters was "large" the authors said.
There was no difference in risk between occasional and regular meat-eaters. Pescatarians had a slightly greater risk (8%) than regular meat-eaters, but this was a non-significant difference, the researchers reported.
Mr Webster emphasised that whilst vegetarians faced a 50% greater risk of hip fracture than meat-eaters, this translated to "just 3 more hip fractures per 1000 people over 10 years".
The authors predicted that on average, 6.5 regular meat eaters and 6.5 occasional meat eaters would experience a hip fracture, whilst there would be 7 cases among pescatarians, and 9.5 cases among vegetarians.
Adequate Nutrient Intake and Weight Management
The authors pointed out that they had only found limited evidence of effect modification by BMI on hip fracture risk across diet groups, and no clear evidence of effect modification by age or sex.
"The lower average BMI in vegetarians explained some of the observed risk difference compared with regular meat-eaters," the authors said, "but a large proportion remained unexplained". Vegetarians were around 17% less likely to meet protein recommendations than meat-eaters, they noted.
Ensuring adequate nutrient intake and weight management was particularly important in vegetarians in the context of hip fracture prevention, they said. "Vegetarians need to ensure they are getting a balanced diet with enough protein and maintain a healthy BMI," urged Mr Webster.
Professor Janet Cade, who leads the Nutritional Epidemiology Group Nutritional Epidemiology Group at the University of Leeds, and who supervised the research, emphasised that whilst vegetarian diets had health benefits, understanding diet quality and the balance of key nutrients might help to "reduce risk and improve future bone health".
"The health benefits of a vegetarian diet, including a lower risk of cancer and cardiovascular disease, may still outweigh any increases in hip fracture risk," Mr Webster suggested.
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