(P29-042-23) Association Between Plant-Based Diets and Risk of Hip Fractures in Women

Objectives: Previous research has found that vegetarian diets are associated with lower bone mineral density and a higher risk of fractures, but these studies did not differentiate the quality of plant-based foods. Therefore, we assessed the association between plant-based diet quality and hip fracture risk among postmenopausal women in the Nurses’ Health Study (NHS).

Methods: We included 70,285 postmenopausal women from NHS (1984-2014). Diet was assessed every 4 years using a validated semi-quantitative food frequency questionnaire. We assessed plant-based diet quality using two previously validated indices – the healthful plant-based diet Index (hPDI) and the unhealthful plant-based diet index (uPDI). In the hPDI, healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, vegetable oils, tea/coffee) received positive scores, while less healthy plant foods (fruit juices, sweetened beverages, refined grains, potatoes, sweets/desserts) and animal foods received reverse scores, thus higher hPDI indicated greater intake of healthy plant foods. In the uPDI, positive scores were given to less healthy plant foods and reverse scores to healthy plant foods and animal foods, thus higher scores indicated greater adherence to less healthy plant foods. Hip fractures were self-reported on biennial questionnaires. Cox-proportional hazards regression with time-varying covariates computed the hazard ratios (HR) (95% CIs) for hip fracture.

Results: We ascertained 2,347 cases of hip fractures during up to 30 years of follow-up. Long-term hPDI or uPDI was not associated with hip fracture risk (hPDI Q5 vs Q1 HR=1.02 (95% CI: 0.89-1.17); uPDI Q5 vs Q11.00 (0.80-1.15). However, when examining recent intake, hPDI was associated with 19% lower hip fracture risk (Q5 vs Q1: 0.81 (0.70-0.94) while uPDI was associated with a 26% higher risk of hip fracture (Q5 vs Q1: 1.26 (1.08-1.47); p-trend=0.01).

Conclusions: Among postmenopausal US women, following a plant-based diet over time was not associated with risk of fracture. However, results differed depending on the quality of the most recent plant-based diets such that higher intake of healthier plant foods was associated with lower risk and higher intake of unhealthy plant foods was associated with higher hip fracture risk.

Funding Sources: ISCIII, FEDER/FSE, NIH