Gut microbes related to the Dietary Approaches to Stop Hypertension score are associated with bone quantity but not with bone quality in a cross-sectional study of older Puerto Rican adults.

BACKGROUND: Bone mineral density (BMD) explains fractures incompletely; studies relating lifestyle to bone quality are lacking. OBJECTIVES: This study aims to examine associations of diet quality with bone measures [bone material strength index (BMSi), trabecular bone score (TBS), BMD], evaluate moderation by inflammation, identify gut microbiome features linked to diet quality, and quantify diet-microbiome-bone relationships. METHODS: This cross-sectional study included participants from the Boston Puerto Rican Osteoporosis Study. Diet was assessed with a culturally tailored food frequency questionnairew, and diet quality with the Dietary Approaches to Stop Hypertension (DASH) score. BMSi was measured using microindentation; BMD by dual-energy X-ray absorptiometry (DXA); TBS derived from DXA. Inflammation was assessed with a biomarker score (BMS) and tested as a moderator of diet-bone associations via interaction terms in linear regression. Gut microbiome composition (shotgun metagenomics) was analyzed with microbiome multivariate association with linear models regression to assess diet associations. A machine learning algorithm determined dietary, microbial, and bone-related predictors of bone health; sample sizes varied by outcome: BMSi (n = 86); TBS (n = 204); BMD femoral neck (n = 220), total hip (n = 221), lumbar spine (n = 207). RESULTS: DASH score was not associated with BMSi [β = -0.10; 95% confidence interval (CI): -0.46, 0.27; P = 0.60], TBS (β = 0.002; 95% CI: -0.002, 0.005, P = 0.36), BMD at the femoral neck (β = 0.002; 95% CI: -0.002, 0.005; P = 0.30), or lumbar spine (β = 0.002; 95% CI: -0.003, 0.006, P = 0.52) but was at total hip (β = 0.004; 95% CI: 0.003, 0.008; P = 0.03). The association was not moderated by inflammation (β = -0.0001, P = 0.89). Lachnospira eligens was 1 of 4 taxa positively associated with DASH score and BMD. No microbial pathways were associated with the DASH score. CONCLUSIONS: DASH score was associated with hip BMD, but not with BMSi or TBS. Select diet-related gut microbes and an inflammation score were associated with BMD. Future studies should examine dietary inflammation in relation to bone quality.