Vegan diets may be linked to a higher risk of bone fractures

A newly published study has found that vegans may be at higher risk of bone fractures than people who incorporate meat into their diet. The risk may also be higher for vegetarians and pescatarians.

Researchers have found that vegans with lower calcium and protein intakes had a 43% higher risk, on average, of experiencing bone fractures than people who ate meat.

The longitudinal study that reached this finding appears in the journal BMC Medicine.

According to the study, among the study participants eating a vegan diet, there were close to 20 more cases of fractures per 1,000 people over a 10-year period. In particular, vegans faced a higher risk of fractures of the hips and legs, as well as other main site fractures, such as the clavicle, ribs, and vertebrae.

“This is the first comprehensive study on the risks of both total and site-specific fractures in people of different diet groups,” says Tammy Tong, lead author and a nutritional epidemiologist at the Nuffield Department of Population Health at the University of Oxford in the United Kingdom.

“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 1,000 people over 10 years.”

– Tammy Tong

Risk with vegetarian and pescatarian diets

Vegetarians and pescatarians — individuals who do not eat meat but do eat fish — also had a higher risk of sustaining hip fractures than people who ate meat, according to the study.

However, the researchers found that taking body mass index (BMI), dietary calcium, and dietary protein into account partly reduced the risk of fractures in these groups.

The researchers analyzed data from nearly 55,000 men and women living in the U.K. who had agreed to participate in the Oxford component of the European Prospective Investigation into Cancer and Nutrition (EPIC) study to examine how diet affects fracture risk.

Of the participants, nearly 30,000 ate meat, about 8,000 were pescatarians, more than 15,000 were vegetarians, and nearly 2,000 were vegans at the time of their recruitment between 1993 and 2001.

Researchers at the Universities of Oxford and Bristol examined the outcomes of the participants by monitoring their hospital records and death certificates until mid-2016. The team followed the participants for more than 17 years, on average.

Over the course of the study, 3,941 fractures occurred in total, including 566 arm, 889 wrist, 945 hip, 366 leg, and 520 ankle fractures and 467 fractures at other main sites, which the researchers established to mean the clavicle, ribs, or vertebra.

The authors observed no significant differences in risks between diet groups for arm, wrist, or ankle fractures once they took BMI into account.

Diet and bone health

Earlier studies have linked calcium and protein intake to bone health. Researchers have also shown that a low BMI is associated with a higher risk of hip fractures but a lower risk of ankle fractures.

Regarding specific diet types, previous studies found that vegetarians had lower bone mineral density (BMD) than those who ate meat.

According to other research, people who follow vegan or vegetarian diets have lower intakes of dietary protein, as well as lower BMIs than those who eat meat. Additionally, vegans may have substantially lower intakes of calcium.

The study’s authors found that the differences in the risk of total and site-specific fractures became less once they factored in BMI, dietary calcium, and dietary protein.

A 2019 analysis found that combined vitamin D and calcium supplements were effective in fracture prevention.

“Well-balanced and predominantly plant-based diets can result in improved nutrient levels and have been linked to lower risks of diseases, including heart disease and diabetes,” says Tong. “Individuals should take into account the benefits and risks of their diet and ensure that they have adequate levels of calcium and protein and also maintain a healthy BMI — that is, neither under nor overweight.”

Vegan bone health requires more research

A 2007 study from the Oxford-EPIC cohort that included almost 35,000 participants also found that vegans had a higher risk of total fractures, but not vegetarians.

However, when the study only looked at the participants who reported consuming at least 525 milligrams a day of calcium, the increased risk dissipated.

Researchers caution that this study had a shorter follow-up period of 5 years and relied on the participants’ self-reporting.

The authors of the new study caution that they were unable to pinpoint the causes of the fractures and did not know whether the participants had used calcium supplements.

They hope to see additional studies looking at non-European populations, as other studies have indicated that there are differences in BMD and fracture risks among ethnic groups.

As three-quarters of the participants in this study were women, the researchers also call for a study with a larger proportion of men to explore differences in risk by sex.

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