Ku Y.H., Kang J.H., Lee H. Effects of Phellinus linteus extract on immunity improvement: A CONSORT-randomized, double-blinded, placebo-controlled trial. Medicine (Baltimore). 2022;101(34):e30226.
Rationale
Phellinus linteus (mesima) is one of East Asia's major medicinal polypores with a long adjunctive-use tradition, but controlled human immune data were thin. This CONSORT-reporting trial measured a functional immune endpoint directly.
Methods
A randomized double-blind placebo-controlled parallel-group trial: 98 adults took 1000 mg/day of fermented P. linteus mycelium extract or 1000 mg/day dextrin placebo for 8 weeks. Primary endpoint: NK-cell activity by LDH cytotoxicity assay; secondary: cytokines and immunoglobulins; safety: liver and kidney panels.
Results
NK-cell activity increased significantly in the mesima group (p<0.05) versus placebo. Secondary cytokine and immunoglobulin measures did not reach significance (trend toward improvement). No hepatic or renal abnormalities.
Conclusions
Eight weeks of mesima extract produced a measurable increase in functional NK-cell activity with a clean safety profile — a real, if modest, human immune signal.
Worth noting
NK activity is a functional assay — more meaningful than cell counts alone. The selective significance (NK yes, cytokines/immunoglobulins no) is honest reporting: immune effects are narrow, not global. n=98 and CONSORT compliance put this above the average supplement trial methodologically.