(P31-09-26) Does Consuming Ultraviolet Light-Exposed Mushrooms Improve Immune Cell Function and Inflammation Status in Adults? Results From a Randomized Controlled Trial

Objectives: Consuming vitamin D₂-containing mushrooms may support the immune system’s response during winter. This exploratory study assessed whether wintertime consumption of UV light-exposed Agaricus bisporus mushrooms (UVM) improves adaptive immune cell response to ex vivo stimulation.

Methods: In this parallel, randomized controlled trial (late fall and winter), 41 adults (22 F, age 43 ± 11 y, BMI 29.8 ± 5.9 kg/m², mean ± SD) complemented their habitual diets with either 84g of fresh UVM twice/d (800 IU of vitamin D₂/d, n = 20) or 1 tsp of breadcrumbs twice/d (Control; n = 21). At baseline and week 6, we collected fasting whole blood. Peripheral blood mononuclear cells (PBMCs) were isolated and frozen at −80°C. Thawed cells were stained with viability dye, Fc block, and surface marker panels and analyzed by flow cytometry to determine immune cell subset frequency (%). In a separate functional assay, PBMCs were cultured in complete RPMI supplemented with IL-2 (50 U/mL) and stimulated with phytohemagglutinin-M (10 µg/mL). After 72 hours, we collected supernatants and quantified cytokines using a cytometric multi-analyte bead assay (LEGENDplex, BioLegend).

Results: Independent of group, total 25OHD decreased (p = 0.008; -4.8 ± 5.8 ng/mL). The composition of most innate and adaptive immune cells did not change after stimulation ex vivo. Within the total CD8⁺ T cell population, % CD8 memory cells increased (p = 0.039; 0.05; 0.01, 0.09, LSMeans; 95% CI) and CD8 naïve cells decreased (p = 0.017; −0.06; −0.12, −0.00) in the UVM group compared to Control. Independent of group, within the total CD4⁺ T cell population, % CCR6⁺ CD4 memory cells decreased (p = 0.009; −0.08; −0.14, −0.02) while regulatory CD25⁺ CD4 memory cells increased (p = 0.029; 0.01; −0.01, 0.03). Corresponding with decreased CCR6⁺ CD4 memory cells, CD80⁺ antigen-presenting cells decreased (p = 0.002; −0.01; 0.02, 0.03). NK cells increased (p = 0.013; 0.01; 0.04, 0.08). IL-2, IL-4, IP-10, TNF-α, IL-6, IL-10, IFN-γ, and IL-8 production did not change.

Conclusions: Daily UVM consumption promoted the CD8⁺ memory T cell phenotype without amplifying pro-inflammatory cytokine production after ex vivo stimulation. Consuming UVM during winter may support adaptive immune function without risking dysregulated inflammation.

Funding Sources: The Mushroom Council