Choi J.Y., Paik D.J., Kwon D.Y., Park Y. Dietary supplementation with rice bran fermented with Lentinus edodes increases interferon-γ activity without causing adverse effects: a randomized, double-blind, placebo-controlled, parallel-group study. Nutrition Journal. 2014;13:35.
Rationale
Fermenting rice bran with shiitake mycelium yields an exo-biopolymer (RBEP) designed to be an oral immune adjuvant; this trial measured its cytokine and NK-cell effects in humans.
Methods
A randomized double-blind placebo-controlled parallel study: 80 healthy adults with leukocyte counts 4000–8000/µL took 3 g/day RBEP or placebo for 8 weeks, measuring serum cytokines including IFN-γ and NK-cell activity.
Results
Serum IFN-γ increased significantly in the RBEP group; NK activity and other cytokines did not change.
Conclusions
RBEP shifted a Th1-polarity cytokine upward — supporting an immune-adjuvant mechanism — while the NK-cell effect seen in other shiitake work did not replicate here.
Worth noting
The honest split — IFN-γ yes, NK no — matters more than either half alone: the immunomodulation is specific, not global. A fermented-bran product is a different material from mushroom powder or extract; RBEP results do not generalize to culinary shiitake.