Differences in fracture risk between diets
There is limited evidence from prospective studies of fracture risk among vegetarians, full vegans, and non-vegetarians, and here is one that aimed to study this in a prospective cohort with a high proportion of non-meat eaters.
In EPIC-Oxford.
Dietary information was collected at baseline (1993-2001) and follow-up (≈2010), and participants were classified into four dietary groups at both time points.
(In the analysis of total fractures.
29,380 meat-eaters
8,037 fish eaters
15,499 vegetarians
1982 vegans.
Outcomes were identified through links to hospital records or death certificates through mid-2016, and multivariate Cox regression was used to estimate total (n = 3941) and site-specific fracture risk.
Results.
Compared to meat eaters, after adjustment for socioeconomic factors, lifestyle confounders, and BMI, the risk of hip fracture was found to be higher in vegans than in meat eaters for leg and other major site fractures.
Overall, the significant association appeared to be stronger without adjustment for BMI, which weakened slightly, but remained significant after further adjustment for dietary calcium and/or total protein.
Tong, T.Y.N., Appleby, P.N., Armstrong, M.E.G. et al. Vegetarian and vegan diets and risks of total and site-specific fractures: results from the prospective EPIC-Oxford study. BMC Med 18, 353 (2020). Available at: https://doi.org/10.1186/s12916-020-01815-3
Summary
The results of the EPIC-Oxford study show that vegans have a higher risk of hip and other fractures than meat eaters, even when accounting for variables such as BMI, which has a strong effect, and hormonal balance, which may make vegans more vulnerable to impact fractures. This is a good thing.
However, there were only a few people in the vegan group who had a higher BMI than the norm, so there was little concern. The results also showed that the vegans in the comparison had less muscle mass. The lower muscle mass also increases the risk of falling when they get older and has a higher risk of fractures.
In addition, the meta-analysis also showed that dietary calcium intake increases bone density, so supplementation with milk or supplements may be advisable.
However, recent experimental evidence suggests that a high-protein diet also increases the efficiency of calcium absorption in the intestine, so supplementing with more protein may be recommended, but epidemiological studies have not proven a link between osteoporosis and a high-protein diet, so it is better to hold off on whether more protein can improve bone density.
The results showed that even with such adjustments for protein and calcium, the risk of fracture was still significantly higher for those on a vegan diet.
I guess we should take into consideration that being biased towards something may have some harmful effects while deciding what to eat.
