If you’re vegetarian, pay extra attention to your bone health. A recent study in BMC Medicine—which followed more than 26,000 women, ages 35 to 69, for 22 years—found that those who ate plant-based diets (vegetarian and vegan) were about one-third more likely to break a hip than regular meat eaters (five or more servings per week). This was true after the researchers controlled for age, ethnicity, menopausal status, physical activity, body weight, smoking, alcohol, and other factors that can affect bone health. Pescatarians (who eat fish but no meat) and occasional meat eaters (less than five servings a week) did not have increased hip fracture risk compared to regular meat eaters. The findings were largely similar to those of two previous cohort studies that followed large groups of people over time.
It’s not clear what accounted for the increased fracture risk, but as the researchers noted, vegetarians tend to have lower intakes of nutrients associated with good bone and muscle health—including protein, calcium, vitamin D, vitamin B12, and omega-3 fatty acids, which are more abundant in animal products than in plant foods.
Vegetarians also tend to have lower bone mineral density, as well as lower body weight. Although there was no clear evidence of body weight affecting the results in any group in this study, higher body weight has long been considered a protective factor for bone health and has been inversely associated with hip fracture risk. That’s possibly because greater muscle and fat mass increase bone strength due to greater mechanical loading on bones, while increased fat may reduce the risk of fractures during falls by acting as a cushion.
The study had several weaknesses, however—for instance, it did not take into account diet changes over time, and it included mostly white European women. More research is clearly needed to tease out the role of diet in the complexity of bone health in this and other populations.
Keep in mind, also, that the study is certainly no reason to forgo a plant-based diet since such diets are associated with reduced risk of many chronic conditions, including heart disease, cancer, and diabetes, not to mention a lower carbon footprint. Rather, the takeaway is that vegetarians—and especially vegans—should take extra steps to ensure that they get enough bone-essential nutrients in their diets (or with supplements as needed), engage in weight-bearing exercise, not smoke, drink alcohol in moderation if at all, and follow recommendations for bone density testing.