Association between visceral adiposity index and bone mineral density: an NHANES study

Objectives: With the improvement of living standards and changes in dietary structure, the number of individuals with central obesity is increasing. Recent studies have indicated that visceral fat accumulation is closely linked to osteoporosis. Therefore, we aimed to explore the relationship between obesity status and bone density mineral (BMD) from a novel perspective of visceral adiposity. Methods: The study included 9,016 participants from the National Health and Nutrition Examination Survey (NHANES) 2007-2010. The visceral adiposity index (VAI) was calculated by anthropometry parameters (body mass index and waist circumference) and functional parameters (triglycerides and high-density lipoprotein cholesterol). Considering the complex survey design and sample weights, we employed multivariate linear regression models and smooth curve fittings to evaluate the correlation between VAI and BMD. For addressing the nonlinear relationship, we employed a two-piecewise regression to calculate the inflection points. Results: After adjusting for multiple covariates, there was a significant positive correlation between VAI and lumbar spine, total femur, and femoral neck BMD. After converting VAI to a categorical variable (quartiles), participants in the highest VAI quartile had a 0.049g/cm 2 higher BMD than those in the lowest VAI quartile (β =0.049, 95%CI: 0.040-0.057, P ＜0.001). In subgroup analyses stratified by age, the relationship between VAI and lumbar BMD was an inverted U-shaped curve in the age ≤18 groups, with a point of inflection at 4.86. Conclusions: VAI was significantly positively correlated with lumbar BMD, demonstrating the complex relationship between visceral fat and bone metabolism. In addition, VAI may be used as a useful predictor of osteoporosis and provide new ideas for the evaluation and screening of osteoporosis.