Reishi

About Reishi

A woody bracket fungus used for centuries in Chinese and Japanese medicine, sold as hot-water extract, ethanol extract, dried powder or spore preparations. Its studied constituents are beta-glucan polysaccharides and ganoderic acid triterpenes.

Reishi has the longest documented traditional use of any mushroom in this catalogue and one of the weaker modern evidence bases relative to how it is sold. A Cochrane review of reishi in cancer found five randomised trials, judged the evidence low quality, and concluded it could not be recommended as a first-line intervention, noting only that some immune parameters shifted. Trials in fatigue, blood glucose and blood pressure are small and inconsistent. Two practical issues matter more than the mechanistic literature: the product problem common to the whole category, and a small but real set of liver injury reports, including a fatal case in Thailand associated with powdered reishi.

Sold as

Hot-water extract capsule, Dual extract (water and ethanol), Dried fruiting body powder, Cracked-wall spore powder, Tincture

Standardised to

Sometimes expressed as percentage polysaccharide or triterpene; a measured beta-glucan figure is more informative than "polysaccharide", which can include grain starch — a product without this marker may not resemble what was studied.

Also known as

Lingzhi, Ling chih, Mannentake, Ganoderma

Regulation: Sold as a dietary supplement in the US with no pre-market efficacy or safety review. Used within licensed traditional medicine systems in China, Japan and Korea, where the preparations are specified differently from most Western retail product.

What the research used

The amounts, forms and durations published trials of Reishi actually administered.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.