Previous studies suggest that bone loss and fracture risk are associated with higher inflammatory milieu, potentially modifiable by diet. The primary objective of this analysis was to evaluate the association of the dietary inflammatory index (DII), a measure of the inflammatory potential of diet, with risk of hip, lower-arm, and total fracture using longitudinal data from the Women's Health Initiative Observational Study and Clinical Trials. Secondarily, we evaluated changes in bone mineral density (BMD) and DII scores. DII scores were calculated from baseline food frequency questionnaires (FFQs) completed by 160,191 participants (mean age 63 years) without history of hip fracture at enrollment. Year 3 FFQs were used to calculate a DII change score. Fractures were reported at least annually; hip fractures were confirmed by medical records. Hazard ratios for fractures were computed using multivariable-adjusted Cox proportional hazard models, further stratified by age and race/ethnicity. Pairwise comparisons of changes in hip BMD, measured by dual-energy X-ray absorptiometry from baseline, year 3, and year 6 were analyzed by quartile (Q1 = least inflammatory diet) of baseline DII scores in a subgroup of women (n = 10,290). Mean DII score improved significantly over 3 years (p < 0.01), but change was not associated with fracture risk. Baseline DII score was only associated with hip fracture risk in younger white women (HR Q4,1.48; 95% CI, 1.09 to 2.01; p = 0.01). There were no significant associations among white women older than 63 years or other races/ethnicities. Women with the least inflammatory DII scores had less loss of hip BMD (p = 0.01) by year 6, despite lower baseline hip BMD, versus women with the most inflammatory DII scores. In conclusion, a less inflammatory dietary pattern was associated with less BMD loss in postmenopausal women. A more inflammatory diet was associated with increased hip fracture risk only in white women younger than 63 years.

IMPORTANCE: Considerable efforts have been undertaken to relate single nutrients to bone health. To this point, results are inconsistent. Suboptimal single nutrient intake does not occur in isolation but rather reflects a poor diet quality. OBJECTIVE: To assess the association between adherence to a diet quality index constructed on the basis of dietary recommendations or existing healthy dietary patterns and fractures in postmenopausal women. DESIGN, SETTING, AND PARTICIPANTS: Post hoc analysis was conducted of longitudinal data from 40 clinical centers throughout the United States included in the Women's Health Initiative (WHI) observational study. Participants in the prospective cohort included 93676 women who were eligible for the WHI if they were aged 50 to 79 years. Recruitment was conducted from October 1, 1993, to December 31, 1998, with the study ending August 29, 2014. The WHI food frequency questionnaire was used to derive nutrient and food intake at baseline. Diet quality and adherence were assessed by scores on the alternate Mediterranean Diet (aMED), a 9-category measure of adherence to a Mediterranean dietary pattern; the Healthy Eating Index 2010 (HEI-2010), a 100-point measure of 12 food components; the 11-item Alternate Healthy Eating Index 2010 (AHEI-2010); or the 8-component Dietary Approaches to Stop Hypertension (DASH) diet score. MAIN OUTCOMES AND MEASURES: Outcome measures included incident total and hip fractures. Hazard ratios (HRs) by quintiles of dietary index scores were estimated using Cox proportional hazards regression analyses. RESULTS: Of the 93676 participants, 90014 were included in the analysis (mean [SD] age, 63.6 [7.4]) years. During a median follow-up time of 15.9 years, there were 2121 cases of hip fractures and 28718 cases of total fractures. Women scoring in the highest quintile (Q5) of the aMED index had a lower risk for hip fractures (HR, 0.80; 95% CI, 0.66-0.97), with an absolute risk reduction of 0.29% and a number needed to treat of 342 (95% CI, 249-502). No association between the aMED score and total fractures was observed (Q5 HR, 1.01; 95% CI, 0.95-1.07). Higher HEI-2010 or DASH scores tended to be inversely related to hip fracture risk, but the results were nonsignificant (Q5 HR, 0.87; 95% CI, 0.75-1.02; and Q5 HR, 0.89; 95% CI, 0.75-1.06, respectively). The AHEI-2010 score was associated with neither hip nor total fractures. CONCLUSIONS AND RELEVANCE: Higher adherence to a Mediterranean diet is associated with a lower risk for hip fractures. These results support that a healthy dietary pattern may play a role in maintaining bone health in postmenopausal women.