Vitamin D2 enriched mushrooms stimulate innate immunity in LPS challenged rats

Vitamin D (vit D) functions in both innate and acquired immunity. The high prevalence of poor vit D status is due in part to limited intake of naturally rich or vit D‐fortified foods. We exposed white button edible mushrooms to UVB light to markedly increase vit D 2 content, creating a naturally rich food source. Our goal was to determine whether the higher vit D 2 content of UVB exposed edible mushrooms is bioavailable and functional in modulating innate immune response in rats acutely challenged with lipopolysaccharide (LPS). For 10 wk, 300 weanling female rats were fed 1 of 5 diets, all formulated based on AIN93G to contain: 1) control levels of vit D; 2) no vit D; 3) no vit D +5% unexposed mushroom; 4) no vit D +2.5% UVB exposed mushroom, and 5) no vit D +5% UVB exposed mushroom (Research Diets, New Brunswick, NJ). After vit D analyses, dry powdered mushroom was added at the expense of non‐nutritive fiber. At wk 10, rats were challenged with either saline (control) or LPS and necropsies were performed at 3, 24 and 72 hrs when spleen cells were evaluated for alterations in natural killer cell activity (NK). NK activity was assessed by the standard 51 Cr release assay using YAC‐1 cells as target cells and rat splenocytes as the effector cells (1:100 ratio). Independent of the saline or LPS challenge, the NK activity was higher in rats fed the highest level (5%) of vit D enhanced mushrooms when compared to the control fed or vit D deficient diets with 5% unexposed or no mushroom. Conclusions Vitamin D 2 from UVB exposed white button mushrooms is bioavailable and effectively functions in innate immunity to stimulate NK activity in a rat model. Source of research support: The Mushroom Council and FDA