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 (VO 2 peak). 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 VO 2 peak ( 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 increased 25OHD, improved body composition, and decreased inflammation. Additionally, vitamin D may mediate inflammation in those who do not exercise.