Does the relationship between 25-hydroxyvitamin D status and bone mass vary according to skin color in adults? Results of a Brazilian population-based study.

ABSTRACT

Skin color has been indicated as an important factor in determining serum concentrations of 25-hydroxyvitamin D [25(OH)D], and consequently bone health. However, studies are controversial and scarce for mixed populations. PURPOSE/INTRODUCTION: To analyze the association of 25(OH)D with bone mineral content (BMC) and bone mineral density (BMD); and to investigate the presence of interaction with skin color in Brazilian adults. METHODS: This is a cross-sectional, population-based study conducted with adult individuals (20-59 years) of both genders. Bone health was assessed by dual energy radiological absortometry. Vitamin D status was measured using serum 25(OH)D. Skin color and other variables in the adjusted model were collected using a questionnaire and anthropometric assessment. Associations and interactions were evaluated using linear regression models stratified according to gender. RESULTS: Non-white men with vitamin D deficiency (< 20.0 ng/mL) have less bone mass than those with insufficiency and sufficiency for the femoral neck and hip sites. According to the adjusted regression analysis, the deficient status of 25(OH)D in men was associated with worse bone health for the lumbar spine sites (ß = - 0.1; p = 0.006), femoral neck (ß = - 0.08; p = 0.006), and hip (ß = - 0.08; p = 0.009). No statistically significant associations were observed between 25(OH)D and bone health in women. In addition, no statistical interaction was identified between skin color and vitamin D status in relation to bone health (p > 0.05 for all tests) in either gender and for all bone sites evaluated. CONCLUSION: Deficient vitamin D status is associated with lower bone mass in adults with differences observed according to gender, but not according to skin color.