Reishi mushrooms, as they are typically referred to in the West, are made up of 90% water by weight. The remaining 10% is rich in protein, dietary fiber and contains various trace minerals and vitamins, with potassium, calcium, phosphorus, magnesium and selenium accounting for most of the mineral content. All of these play a role in the many reported health benefits of reishi mushrooms.
The medicinal mushrooms contain a wide variety of bioactive molecules, with polysaccharides, peptidoglycans and triterpenoids being the major and most researched constituents. Polysaccharides, which are sub-divided into β-1,3-glucans and polysaccharide peptides like peptidoglycans, are reported to demonstrate a wide range of activities. These include antiinflammatory, anticancer, antiulcer, hypoglycemic (sugar regulating) and most notably, stimulating the production of immune cells—with the latter driven by the activity of β-1,3-glucans. Triterpenes, which are found in high quantities in the mushroom and are responsible for their bitter taste, have been shown to exhibit lipid-lowering and antioxidant properties.
When looking at effective therapeutic applications, the desired goal is to offer value with little to no toxicity. Research to date on the therapeutic potential of reishi mushrooms demonstrates its role in relation to chronic diseases like cancer and diabetes, as well as viral and bacterial infections and liver disease.
To date, there is considerable evidence supporting the immune cell stimulating effects of reishi, which could result in improved protection against invaders and the removal of dangerous or cancerous cells. The antioxidant effects of polysaccharides and triterpenes in reishi have also been demonstrated in in vitro (outside of organism) studies, owing largely to the rich polyphenolic content in these molecules. Antioxidants offer protection against oxidative damage, which is likely to reduce the risk of mutations and cancer, and also protect cells of the immune system so they can continue to work efficiently.
Hundreds of plant species, including mushrooms, have been studied in the search for preventative and therapeutic agents against cancer. Many polysaccharides and triterpenes in reishi have been shown to demonstrate anticancer, or more specifically, antitumor activity, in vitro and in vivo (inside organism) studies through various mechanisms of action, including inhibiting or down-regulating critical enzymes involved in cancer cell growth. Promising antitumor activity has been demonstrated in several cancer cell lines, including prostate, colon, breast and lung.
Randomized, controlled trials on cancer patients supplementing with reishi have also demonstrated positive outcomes. In one trial, patients with advanced cancers of different types were supplemented with a dosage of 1800 mg/day of reishi for 12 weeks. In 80% of patients, there was a significant increase in levels of key immune cells, as well as natural killer (NK) cell activity.
Another human trial by the same research group looked at lung cancer patients supplementing with reishi and also showed significantly increased levels of immune cells in the reishi-treated group, along with increased quality of life scores in 65% of patients. These results provide some evidence that the anti-cancer properties of reishi are associated with its effects on the immune system.
The inhibition of viral and bacterial multiplication is another area of reishi mushroom research. This is due to two factors: 1) the need for new agents with less side effects; and 2) the rise of resistant and mutant strains in response to current therapies. Current in vitro research demonstrates the inhibited replication of herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), human immunodeficiency virus (HIV)-1 and hepatitis B virus. However, further research is needed to understand the mechanisms of action.
Small trials on patients with varicella zoster virus, which causes chicken pox and shingles, have also reported beneficial effects of the mushroom taken orally, however additional studies are needed to validate results. In vitro and in vivo studies have also been done with reishi to explore its antibacterial potential, with inhibitory effects demonstrated against multiple bacterial strains. While promising preliminary data exists, further research is required for both antiviral and antibacterial studies.
Components of reishi have also been shown to have hypoglycemic or blood glucose modulating effects in animal studies, either alone or in combination with conventional treatments. Reishi has also demonstrated protection against liver and gastric injuries in animal studies, through several different mechanisms of action.