We often hear about the health benefits of veganism, vegetarianism and other diets low in red and other meat. While those benefits are often legitimate, it seems that some diets may put you at a higher risk for bone fractures. What might cause this bone fracture risk?
According to the analysis of data from the EPIC-Oxford study performed by the Universities of Oxford and Bristol in the United Kingdom, vegans, vegetarians and pescetarians have a problem. Their findings indicate an increased risk of both total fractures (anywhere in the body) and site-specific fractures for many people on these diets.
A prospective cohort study is one in which researchers identify a group of people, usually based on physical characteristics (gender, age, common ailment,) location or lifestyle habits (diet, exercise, smoking, etc.) and follow them for a period of time to assess how certain factors influence specific health or other outcomes.
For this study, 54,898 participants in the EPIC-Oxford study were selected to have their health data from the study analyzed by the Oxford-Bristol team. The cohort included men and women recruited to the EPIC-Oxford study between 1993 and 2001. Many of these were not meat-eaters.
29,380 of the EPIC-Oxford participants whose data was reviewed ate meat. Of the rest, 1,982 were vegans, 15,499 were vegetarians and 8,037 were pescetarians (eating fish but no meat.) Participants in the study were tracked for an average period of 18 years. Their eating habits had been assessed at the time of their recruitment and reassessed in 2010.
The total of fractures for all participants for the EPIC-Oxford study period was 3,941. Of those, 945 were hip fractures, 889 wrist, 566 arm, 520 ankle, 366 leg and 467 fractures at sites like the ribs, vertebrae and clavicle.
In findings published in the open access journal BMC Medicine, the study found that vegans with lower protein and calcium intakes had an average 43% higher risk of total fractures. They also had a higher risk of site-specific fractures, including the hips, vertebrae and legs. Compared with meat eaters, pescetarains and vegetarians showed a higher risk of hip fractures. Once dietary protein and calcium, along with body mass index (BMI) were accounted for, that risk was somewhat lower.
Study lead author Dr Tammy Tong, Nutritional Epidemiologist at the Nuffield Department of Population Health, University of Oxford, said: “This is the first comprehensive study on the risks of both total and site-specific fractures in people of different diet groups. 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. 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.”
The news seems to be the worst for vegans. While vegans, vegetarians and pescetarians all had higher hip fracture risk, the vegans could add a higher risk of leg and other main site fractures to their risk list. Interestingly, once BMI was accounted for, there were no observable, significant differences in risk of ankle, arm or wrist fractures between the groups.
Dietary calcium, dietary protein and BMI seem to play a key role in reducing the risk of fractures. Once these were accounted for, researchers saw the risk of both total fractures and site-specific fractures partly reduced for all three groups.
Dr Tong said: “Previous studies have shown that low BMI is associated with a higher risk of hip fractures, and low intakes of calcium and protein have both been linked to poorer bone health. 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. 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. 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.”
Data on the actual causes of the fractures weren’t available. Because of this, it is impossible to know which fractures were related to poorer bone health (like those that occur during a fall from standing height or lower) and those related to accidents. It was also noted that the researchers couldn’t get a fully accurate measure of dietary calcium and dietary protein, since their estimates couldn’t take into account any supplementation of either nutrient.
Another acknowledged limitation of the study had to do with demographics. Since the study included predominantly white Europeans, it’s difficult to generalize the results to other ethnicities or populations. The authors believe this could be significant, since previous studies have observed variations in both bone mineral density and risk of fractures in different ethnicities.
The researchers think more studies will help. Looking at various populations, including non-Europeans, will broaden the cohort allow for risk ranking by region and ethnic background. They’d also like to study more men, since about 75% of the participants in the EPIC-Oxford study were women.
With all the health benefits of vegan, vegetarian and pescetarian diets, this was a somewhat surprising result. Being aware of dietary calcium and dietary protein should mitigate the risk somewhat. It just means paying attention to what you eat. Of course, successful dieting of any kind has that as a foundation!
Keep the faith and keep after it!
Journal Reference – Tammy Y. N. Tong, Paul N. Appleby, Miranda E. G. Armstrong, Georgina K. Fensom, Anika Knuppel, Keren Papier, Aurora Perez-Cornago, Ruth C. Travis, Timothy J. Key. Vegetarian and vegan diets and risks of total and site-specific fractures: results from the prospective EPIC-Oxford study. BMC Medicine, 2020; 18 (1) DOI: 10.1186/s12916-020-01815-3