In so-called alternative medicine (SCAM), we have numerous diets that are either promoted for specific conditions or that are popular in a more general sense. Meat-free forms of nutrition can perhaps not be characterised as SCAM, but they are certainly popular with consumers as well as practitioners of SCAM. It is often said that meat-free diets are healthy, but few entusiasts like to consider that it might be associated with health risks.
This study tested whether vegetarianism and veganism are risk factors for bone factures in a prospective cohort with a large proportion of non-meat eaters.
In EPIC-Oxford, dietary information was collected at baseline (1993–2001) and at follow-up (≈ 2010). Participants were categorised into four diet groups at both time points (with 29,380 meat eaters, 8037 fish eaters, 15,499 vegetarians, and 1982 vegans at baseline in analyses of total fractures). Outcomes were identified through linkage to hospital records or death certificates until mid-2016. The risks were calculated of total (n = 3941) and site-specific fractures (arm, n = 566; wrist, n = 889; hip, n = 945; leg, n = 366; ankle, n = 520; other main sites, i.e. clavicle, rib, and vertebra, n = 467) by diet group over an average of 17.6 years of follow-up.
Compared with meat eaters and after adjustment for socio-economic factors, lifestyle confounders, and body mass index (BMI), the risks of hip fracture were higher in
- fish eaters (hazard ratio 1.26; 95% CI 1.02–1.54),
- vegetarians (1.25; 1.04–1.50),
- vegans (2.31; 1.66–3.22).
This was equivalent to rate differences of 2.9 (0.6–5.7), 2.9 (0.9–5.2), and 14.9 (7.9–24.5) more cases for every 1000 people over 10 years, respectively. The vegans also had higher risks of total (1.43; 1.20–1.70), leg (2.05; 1.23–3.41), and other main site fractures (1.59; 1.02–2.50) than meat eaters. Overall, the significant associations appeared to be stronger without adjustment for BMI and were slightly attenuated but remained significant with additional adjustment for dietary calcium and/or total protein. No significant differences were observed in risks of wrist or ankle fractures by diet group with or without BMI adjustment, nor for arm fractures after BMI adjustment.
The authors concluded that non-meat eaters, especially vegans, had higher risks of either total or some site-specific fractures, particularly hip fractures. This is the first prospective study of diet group with both total and multiple specific fracture sites in vegetarians and vegans, and the findings suggest that bone health in vegans requires further research.
The effect is by no means large, and I doubt that it will persuade many non-meat eaters to change their diet. However, perhaps the study can serve as a reminder that people who avoid meat might some lack essential nutrients and that they should therefore consider making sure that no deficiencies can develop.