LAUSR

BACKGROUND In obesity, low levels of vitamin D (VD) and vitamin B12 (VB12) may be the result of different pathophysiological mechanisms, but the possible association between them has not been defined yet. The aim of this cross-sectional analysis was to investigate the possible relationship between serum 25-hydroxyvitamin D (25(OH)D) and VB12 levels in middle aged women. METHODS In 80 women, we indirectly evaluated body composition and body volumes [extracellular fluid volume (ECV) and total body water (TBW)] by anthropometric and bioelectrical impedance analysis. Vitamin D and VB12 status was assessed by laboratory measurement [serum 25(OH)D levels by electrochemiluminescent immunoassay; VB12 by chemiluminescent microparticle immunoassay]. RESULTS Obese women were mostly VD deficient [25(OH)D below 50 nmol/L; 40/50, 80%]. Also, among obese we observed presence of VB12 deficiency [VB12 below 148 pmol/L; 13/50, 26%) and marginal depletion of VB12 level (marginal VB12 status 148-221 pmol/L; 20/50, 40%). All anthropometric indicators of obesity, ECV and TBW were significantly associated with both, 25(OH)D and VB12 (P<0.001) levels. In univariate regression analysis serum level of 25(OH)D was significantly associated with VB12 levels (R2=0.170, P<0.001). In regression models, 25(OH)D was significantly associated with VB12 level, independently of fat mass and extracellular fluid volume. CONCLUSIONS Obesity may negatively affect VB12 level, indirectly, by reducing 25(OH)D level in middle aged women.