Dai X., Stanilka J.M., Rowe C.A. et al. Consuming Lentinula edodes (Shiitake) Mushrooms Daily Improves Human Immunity: A Randomized Dietary Intervention in Healthy Young Adults. J Am Coll Nutr. 2015;34(6):478–487.
Rationale
Most immune-mushroom evidence used extracts; this study asked whether ordinary dietary quantities of whole shiitake do the same — the practically relevant question.
Methods
A randomized parallel dietary intervention: 52 healthy adults (21–41) ate 5 or 10 g/day of dried shiitake for 4 weeks, with ex vivo lymphocyte function, activation-receptor expression, salivary sIgA and CRP as readouts.
Results
γδ-T-cell ex vivo proliferation rose 60% and NK-T cell proliferation doubled (both p<0.0001); both populations expressed activation receptors more strongly. Salivary secretory IgA increased; C-reactive protein fell.
Conclusions
A month of eating shiitake at culinary doses produced measurable immune-function gains and lower systemic inflammation in healthy young adults.
Worth noting
This is the second card covering the same Dai et al. 2015 dataset (the catalog keeps both the immune-marker and dietary-framing writeups). The activation-receptor detail distinguishes this from a simple count increase — the cells were not just more numerous but functionally primed. Food-matrix research like this is what "mushrooms and immunity" claims should cite — not extract data extrapolated to soup.