Clinical trial to analyze the effects of oral intake of Phellinus linteus (sanghuang) extract on immune function: a study protocol for a randomized, double-blind controlled trial

Abstract Background As the population of Korea ages, interest in healthcare has increased. In particular, there is an increasing demand for immune-function improvement to prevent infectious diseases. Phellinus linteus (PL) has previously been shown to exert immune-enhancing and anticancer effects. We aim to evaluate whether PL mycelium extract, cultured from the PL KCTC0399BP strain, can increase immune function, as measured using blood-test indicators. This clinical trial protocol is designed as the main trial and is based on the results of a pilot study. Methods This clinical trial is a randomized, double-blinded, placebo-controlled trial. Ninety-eight participants are enrolled and randomly divided into two groups: the experimental group (PL 1000 mg) and the control group (placebo). Participants are administered with experimental food or placebo for eight weeks. Blood tests are performed before trial initiation and 8 weeks later, at trial completion. Laboratory evaluation items are as follows: natural killer cell activity, tumor necrosis factor-α, interferon-γ, interleukin (IL)-1β, IL-2, IL-6, IL-12, immunoglobulin (Ig)G1, IgG2, and IgM. We will mainly use the full analysis dataset to statistically analyze the effectiveness of the treatment. Discussion This study evaluates the effects of PL extract on immune function and will contribute to knowledge on the value of PL as an immune-function–boosting functional food. Trial registration Clinical Research Information Service (CRIS) of Korea CRIS-KCT0005460 . Registered on 12 October 202