Objective Our aim in this study is, does 29-day regular consumption of Pleurotus ostreatus water extract by volunteer individuals who meet the study criteria have an effect on blood and cytokine values? Method In accordance with the purpose of the study, volunteers were asked to consume 100 ml of the extract every morning for 29 days. Three tubes of blood samples were taken from the volunteers on the 15th and 29th days of the study. Biochemical and hematological analysis of the blood samples were performed and immunomodulatory effects through cytokines were examined. The values obtained from 3 tubes of blood obtained from volunteers before the use of mushroom extract were used as control. The chemical composition and β-glucan content of 100 ml of mushroom water extract were also analyzed. Result IL-4, IL-6, IL-10 and IL-13 could not be detected because the values were below the lowest standard value. TNF-α, IFN-γ and IL-1β 15th and 29th day values decreased compared to the 1st day (control) values (p < 0.05). However, there was no significant difference observed between the 15th and 29th day. No abnormalities were observed in biochemical and hematological values. Also, the β-glucan content of extract was found 38.12 mg/100 ml. Conclusion The frequency range of kidney and liver function test results confirmed that P. osreatus is a reliable food source. Considering the cytokine values these results indicate that P. ostreatus water extract has an anti-inflammatory effect. As no significant difference was observed in 29 days of use, it is thought that 15 days of daily consumption of the extract may be sufficient for the anti-inflammatory effect to occur. However, a large number of qualified clinical trials are needed to support the issue.