Optimal Vitamin D Status is Associated with Healthier Immune Indices in Untrained, but not Trained Females

The anti-inflammatory effects of chronic exercise are well established; less is known about immune changes associated with vitamin D. This study explored the relationship between inflammatory indices in exercise trained (TR) and untrained (UN) individuals with 25-hydroxyvitamin D (25OHD) concentrations either above (HD) or below (LD) optimal concentrations. Subjects (n=63, 19-35 years) were evaluated for body composition and maximal aerobic capacity (VO2peak). 25OHD levels, lipopolysaccharide (LPS)-stimulated interleukin-6 (IL-6) production, and inflammatory monocytes and toll like receptor 4 (TLR4) expression were determined in whole blood. TR (n=30) had higher 25OHD levels (p=0.015) and VO2peak (p<0.0001), lower body weight (p=0.039) and percent body fat (p=0.011), and lower LPS-stimulated IL-6 production (p=0.0163) compared to UN (n=33). UN with HD had lower numbers of total monocytes, CD14+CD16- cells, and lower TLR4 expression on CD14+CD16+ cells compared to UN with LD. Exercise was related to increa...