Bone Mineral Density Variation Across Anatomical Regions: Insights From the National Health and Nutrition Examination Survey

Abstract

Objectives

Bone mineral density (BMD), a critical measurement of overall bone health, is sensitive to nutritional, hormonal, immunological, lifestyle, and genetic factors through their impact on bone remodeling and age-related BMD loss. Further, bone responds to repetitive mechanical loading by increasing bone mineral deposition, suggesting that differences in bone loading could moderate associations between age and BMD by buffering weight-bearing regions against age-related resorption. We examine whether age-BMD relationships differ across skeletal sites and between weight-bearing (WBR) and nonweight-bearing (non-WBR) regions.

Methods

Data from adult participants (n = 12,403) of the National Health and Nutrition Examination Survey (NHANES; 2007–2018) were analyzed using multivariate linear regression, adjusting for body mass index, gender, racialized group, socioeconomic status, smoking, alcohol consumption, and sedentary behavior. BMD was evaluated across 12 anatomical regions.

Results

WBR and non-WBRs showed similar age-related declines in BMD overall, though this pattern varied by gender. Women showed a steeper age-related BMD decline in non-WBRs; men showed comparable negative associations between regions. Non-Hispanic Black participants had significantly higher BMD in every region than non-Hispanic White participants. Socioeconomic status and heavy smoking were strong predictors of BMD. Notably, increased sedentary time was linked exclusively to lower BMD in non-WBRs (all p < 0.001).

Discussion

These results indicate habitual loading alone may be insufficient to buffer bones against age-related loss. Rather, social and lifestyle factors significantly moderate the age-BMD relationship. Further research employing longitudinal data, direct mechanical loading measurements, and bone microarchitecture assessments could help clarify the interplay of biomechanical and social factors influencing BMD.