Medicinal Mushrooms Simply Explained

1. What It Is About

Medicinal mushrooms are mushroom species that have long been used in Asian medicine. The best known are Reishi, Chaga and Cordyceps. Teas, powders or capsules are made from them. The mushrooms contain substances such as polysaccharides (multiple sugars) and triterpenes (a group of plant substances). These substances show effects on the immune system, on inflammation and on oxidative processes (harmful conversion processes in the body) in laboratory and animal studies. Preparation of the mushrooms varies: water mainly extracts the multiple sugars, alcohol rather the triterpenes. This is why the extracts in studies are often not the same. Sometimes several mushroom species or additives such as vitamins are also mixed. This makes comparison of the studies difficult. Research in humans is still limited: there are 41 controlled studies in which humans were examined, alongside many observational studies and review articles. Most controlled studies examine safety and effects on the immune system.

2. What Studies Show

Tolerability is the best documented. In a controlled study with 88 men with urinary complaints, participants took a Reishi extract daily for 12 weeks. No serious side effects occurred and blood values remained unchanged. The complaints improved slightly 3. A 2021 review summarises that clinical studies on Reishi mostly reported only mild side effects such as nausea, diarrhoea or muscle pain; serious side effects were not observed 5. Another controlled study with 16 healthy people showed that Reishi was safe over 10 days and caused no laboratory changes 2. There are indications regarding the immune system: in a randomised study, certain white blood cells (lymphocytes) increased under Reishi extract 4. Whether this had a benefit for the participants’ health was not examined. In cancer as adjunct therapy, review articles found insufficient evidence for a direct effect against the tumour. There were, however, indications of better quality of life and a stronger immune response, especially when the mushroom extracts were given together with chemotherapy. A large 2016 review reports that quality of life improved in 65 % of lung-cancer patients under Reishi. The authors emphasise that mushroom extracts are considered a supportive measure, not a direct therapy. In rheumatoid arthritis (an inflammatory joint disease), a small pilot study with 65 participants showed that pain and general well-being improved under a mixture containing Reishi, but inflammatory markers in the blood remained unchanged 1. There are still no clear results in humans regarding oxidative stress and metabolism.

3. What Remains Unclear

Many studies are small, often not blinded and use different extracts. This makes it difficult to compare the results. Most studies come from Asia, where medicinal mushrooms are traditionally used; cultural habits could influence the results. There are hardly any data on long-term effects, on certain diseases such as diabetes or cardiovascular conditions, and on changes in the gut flora. It is also unknown whether the observed changes in the immune system actually bring noticeable health benefits. There is insufficient evidence for a direct effect against cancer. The open questions are: which mushroom species, which preparation and which amount are useful? And how do the mushrooms act with longer-term intake?

4. What This Means in Everyday Life

Medicinal mushrooms are well tolerated and there are indications of a supportive effect on the immune system and well-being. They are not proven as a standalone treatment for diseases. Anyone wishing to try them should discuss this with a doctor, especially if they are already taking medication. There are indications that mushroom extracts can alter the effect of medicines, for example chemotherapy or antibiotics. Such interactions have not yet been sufficiently studied in humans. The most important next question is whether standardised extracts show an actual benefit in larger, well-planned studies for specific diseases.

All Details with Study Numbers and Sources: detailed page on medicinal mushrooms (Reishi, Chaga, Cordyceps). For children: medicinal mushrooms (Reishi, Chaga, Cordyceps) for children.