Impact of dietary index for gut microbiota on muscle and bone health: A cross-sectional study

Distortions in homeostasis of the gut microbiota may be correlated with or may even contribute to abnormalities in musculoskeletal system function. This study thus aims to examine the impact of dietary index for gut microbiota (DI-GM) on bone and muscle health. This study utilized data extracted from the National Health and Nutrition Examination Survey database. Dietary data was used to calculate DI-GM. Osteoporosis, bone mineral density (BMD), sarcopenia, muscle quality index (MQI) and fracture were selected as observational indicators in this study. The random forest algorithm filled in the missing data. The weighted data were utilized to create logistic or linear regression models. Odds ratios (ORs) or beta, along with their corresponding 95% confidence intervals (CIs), were calculated. In addition, restricted cubic spline and stratification analysis were performed. DI-GM decreased the risk of osteoporosis (OR: 0.96; 95% CI: 0.93-0.996; P = .03). DI-GM decreased the likelihood of sarcopenia (OR: 0.86; 95% CI: 0.77-0.96; P = .01) and increased MQI (beta: 0.02; 95% CI: 0.01-0.03; P = .002) and BMD (beta: 0.003; 95% CI: 0.001-0.005; P = .001). However, no association was observed between DI-GM and sarcopenia, BMD, MQI after adjusting for covariates. Nevertheless, no correlation was observed between DI-GM and fracture. Additionally, a nonlinear relationship between DI-GM and osteoporosis was found after adjustment (P = .002), with an inflection point at 3.97 (median is 4), and risk dropped rapidly above this threshold. DI-GM decreases the risk of osteoporosis and sarcopenia and increases BMD and MQI, especially osteoporosis. However, it had no effect on fractures.