As of 2015, limited research suggests that reishi mushroom extract may help to prevent cancer growths, lower blood pressure and improve liver function, according to Healthline. More research is necessary to prove any beneficial properties of the extract, notes WebMD.
A small amount of research indicates that in individuals with colorectal ademonas, taking a supplement of reishi mushroom extract daily over a period of one year may reduce the number of benign tumors in the colon and rectum, notes WebMD. Limited research also suggests that the extract may lower blood pressure when taken daily for at least 12 weeks; however, this effect only occurred in patients with severe high blood pressure.
Reishi mushrooms may have a blood-thinning effect, notes Healthline. Patients who are already taking anticoagulants or other blood pressure medications should consult a doctor before starting to take reishi mushroom extract. Researchers have yet to perform clinical trials to test this property of the extract.
Reishi mushrooms, particularly the red variety, contain antioxidants. While research has theoretically linked antioxidants to anti-cancer and anti-tumour benefits, science has not proven this link, according to Healthline. Reishi mushroom extract is generally safe when taken orally for up to one year, notes WebMD.