Relation of Serum 25(OH)-Vitamin D to Fat Mass and Lean Mass, Bone Mineral Content and Body Composition in Adults – a DXA-Based Study

Obesity has been linked with vitamin D deficiency in a number of cross-sectional studies, reviews and meta-analyses. The aim of the present study was to assess the correlations of plasma 25(OH) vitamin D levels with indices of body composition examined by DXA with an emphasis on lean and bone mass as well as on indices such as android/gynoid fat, appendicular lean mass, fat-mass indexes (FMI) and fat-free mass indexes (FFMI). 62 adult subjects consented to participate – 27 men (43.5%) and 35 women (56.5%). Their mean age was 45.3 ± 9.5 years. Fan-beam dual-energy X-ray (DXA) body composition analysis was performed on a Lunar Prodigy Pro bone densitometer with software version 12.30. Vitamin D was measured by electro-hemi-luminescent detection as 25(OH) D Total (ECLIA, Elecsys 2010 analyzer, Roche Diagnostics). Statistical analyses were done using the SPSS 23.0 statistical package. The serum 25(OH)D level was correlated significantly only to the whole body bone mineral content, the appendicular lean mass index (ALMI) and the ALM-to-BMI index, underlining a predominant role for lean and fat-free mass. Vitamin D showed a very weak correlation to % Body Fat and the Fat Mass Index (FMI) in men only. Moreover, the multiple regression equation including the associated parameters could explain only 7% of the variation in the serum 25(OH) D levels. Our conclusion was, that there are differences in the associations of the vitamin D levels with the different body composition indices, but these associations are generally very weak and therefore – negligible.