On the potential differences in fracture risks between vegetarians, vegans, and non-vegetarians, there is a paucity of prospective evidence.
Adult and older age-related fractures are a prevalent occurrence that place a heavy load on health systems around the world. Although vegetarian diets may increase the risk of fracture, previous epidemiological research have revealed that vegetarians had lower bone mineral density (BMD) than non-vegetarians. Different risks could exist, and this is feasible.
But due to variations in a number of dietary components, such as the significantly lower calcium intakes in vegans, the lower dietary protein intakes in vegetarians and vegans, and the lower body mass index (BMI) of non-meat eaters.
Both calcium and protein intakes have been connected to bone health in previous research, but their connections to fracture risks are complex. Although earlier meta-analyses on calcium revealed that calcium supplements can produce modest increases in BMD, it is less certain if this level of improvement would be adequate to lower the risk of fracture. However, a recent meta-analysis of randomised trials revealed that calcium supplementation when paired with vitamin D supplementation was effective in preventing fractures, whereas vitamin D supplementation alone did not. This finding supports the significance of calcium.
With regard to protein, more recent research has suggested a positive relationship between protein and bone health, even though this might not translate to differences in fracture risk. Older studies had suggested that a high protein diet might cause higher calcium excretion and, consequently, weaker bones.
A recent study revealed that the decreased BMD seen in US vegetarians may be mostly explained by their lower BMI and waist circumference because BMI is also a crucial factor for fracture risk. Low BMI has been linked to a higher risk of hip fracture but a lower risk of ankle fracture, with the directions of relationship between BMI and fracture risk varying between fracture sites. However, this analysis had a short follow-up (5 years) and relied on self-reported outcome data.
The largest study to date on the vegetarian diet group and fracture risks came from previous analyses in EPIC-Oxford on roughly 30,000 participants and reported that vegans, but not vegetarians, had higher risks of total fractures. The only other two studies on the subject had few participants and didn’t document site-specific fractures. As a result, it is still unknown if the risk of fracture varies depending on the location of the fracture or by vegetarian diet groups.
Using a prospective cohort with an average follow-up of nearly 18 years and a significant number of site-specific fractures, this study sought to investigate the risks of total and site-specific fractures. Dietary data were gathered for this large cohort EPIC-Oxford study at baseline (1993–2001) and the follow-up until 2010. At both time points, the UK’s roughly 65,000 participants were divided into four diet groups (with 29,380 meat eaters, 8037 fish eaters, 15,499 vegetarians, and 1982 vegans at baseline in analyses of total fractures).
Up until the middle of 2016, outcomes were determined by linking to hospital records or death certificates. The study calculated the risks of total (n = 3941) and site-specific fractures (arm, wrist, hip, leg, ankle, and other key sites, such as clavicle, rib, and vertebra, n = 467) over an average of 17.6 years of follow-up for each diet group using multivariable Cox regression.
In comparison to meat eaters, fish eaters had higher hip fracture risks (hazard ratio 1.26; 95% CI 1.04-1.54), vegetarians had higher hip fracture risks (1.25; 1.04-1.50), and vegans had higher hip fracture risks (2.31; 1.66-3.22). These differences correspond 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 a ten-year period, respectively. In addition, compared to meat eaters, vegans had greater rates of overall (1.43; 1.20-1.70), leg (2.05; 1.23-3.41), and other primary site (1.59; 1.02-2.50) fractures. Overall, the significant relationships seemed to be stronger when BMI was not taken into account, and they were slightly less but still significant when dietary calcium and/or total protein were taken into account.
The risks of wrist or ankle fractures by diet group, with or without BMI correction, as well as the risks of arm fractures following BMI adjustment, did not differ significantly.
According to the study’s findings, non-meat eaters, particularly vegans, were more likely to sustain total or site-specific fractures, particularly hip fractures.
This is the first prospective study of a food group that includes total and many distinct fracture sites in vegetarians and vegans, and the results imply that further study is necessary to understand the bone health of vegans.