Cross-sectional associations between adipose tissue depots and areal bone mineral density in the UK Biobank imaging study

Summary: The relationship between obesity and osteoporosis is poorly understood. In this study, we assessed the association between adiposity and bone. The fat–bone relationship was dependent on sex, body mass index classification, and menopausal status. Results highlight the importance of accounting for direct measures of adiposity (beyond BMI) and menopause status. Introduction: Assess the relationship between direct measures of adiposity (total body fat mass, visceral adipose tissue, and abdominal subcutaneous adipose tissue) with the whole body and clinically relevant bone sites of the lumbar spine, and femoral neck areal bone mineral density (aBMD) in men and women. Methods: This cross-sectional analysis was conducted utilizing de-identified data from the UK Biobank on participants (n = 3674) with available dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI) data. Sex-stratified multiple linear regression was used to assess the relationship between adiposity measures and aBMD outcomes, controlling for age, race, total body lean mass (DXA), height, BMI class, physical activity, smoking, menopausal status (women), and hormone use (women). Results: In men, significant interactions were observed between measures of adiposity and BMI on aBMD for the whole body and lumbar spine. Interactions indicated a positive relationship between adiposity and aBMD in men classified as normal weight, but an inverse relationship in men with elevated BMI. In women, significant interactions between adiposity measures and menopausal status were observed primarily for the whole body and femoral neck aBMD bone outcomes which indicated a negative relationship between adiposity and aBMD in premenopausal women, but a positive relationship in postmenopausal women. Conclusion: Total body adiposity, abdominal subcutaneous adipose tissue, and visceral adipose tissue were all significantly associated with aBMD in both men and women. The strength and direction of association were dependent on sex, BMI classification, and menopausal status (women).