Medicinal Mushrooms & Supplements

What lies behind medicinal mushrooms

Healing mushrooms such as the lacquered bracket, better known as Reishi, have been used in Asia for more than 2,000 years. The active compounds are considered to be mainly beta-glucans, that is, polysaccharides from the cell wall, and in some species triterpenes. What is sold is either the dried fruiting body, that is, the visible mushroom, or the mycelium, the fungal network, which is often grown on grain.

This makes a difference. Mycelium grown on grain contains a lot of starch from the growth medium, which with some measurement methods can distort beta-glucan values. According to the Verbraucherzentrale (German consumer advice centre), the fruiting bodies of the caterpillar fungus and the lacquered bracket have been used as food supplements in the EU for more than 20 years, but mycelium powder has not.

The four best-known mushrooms

Reishi has the most studies, with mixed results: for fatigue there is a positive signal, while for blood sugar, blood lipids and blood pressure Cochrane analyses show no effect. Lion’s mane is advertised for concentration and memory because of possible nerve growth factors; the human data are small but encouraging. Cordyceps is considered an endurance mushroom; pooled sports studies show slight improvements, while a controlled study in cyclists found no effect. Chaga is popular as a tea and antioxidant; no controlled studies in humans were found.

How to recognize good products

Reputable products state the mushroom species with its Latin name, say whether fruiting body or mycelium was used, and name the extraction method. Good manufacturers provide a certificate of analysis that lists beta-glucan and alpha-glucan, that is, starch, separately, plus tests for heavy metals, pesticides and mycotoxins. Healing claims against cancer, rheumatism or depression should make you skeptical, because they are not permitted for food supplements. Advice in a shop is good if it also says what a mushroom is not supported for.

What the studies show

Reishi for fatigue, 2005

Tang and colleagues gave 132 patients with neurasthenia a Reishi polysaccharide extract or placebo for 8 weeks. Severity and fatigue fell significantly more under the extract; 51.6 versus 24.6 percent were more than minimally improved. The extract was well tolerated.

Lion’s mane in mild cognitive impairment, 2009

Mori and colleagues divided 30 Japanese people aged 50 to 80 into two groups. After 8, 12 and 16 weeks, scores in the cognitive test under lion’s mane were significantly above placebo. 4 weeks after stopping, they fell markedly again, so the effect lasted only while intake continued.

Reishi for cardiovascular risk factors, Cochrane 2015

Klupp and colleagues found 5 studies with 398 participants. Reishi lowered neither long-term blood sugar (HbA1c) nor blood lipids or blood pressure to a statistically or clinically meaningful degree.

Where the data stop

The big promises are not supported. A 2016 Cochrane analysis found only 5 randomized studies on Reishi in cancer, and none of them recorded long-term survival. A 2025 systematic review on lion’s mane rests on 5 randomized studies, plus pilot and laboratory studies. Many studies come from Asia, are small and each uses a different preparation, so the results can hardly be transferred to any product off the shelf. A study in 22 cyclists found no effect of 5 weeks of Cordyceps on endurance or oxygen uptake.

Then there is the question of quality. According to the Verbraucherzentrale, medicinal mushroom products often do not contain the stated substances or amounts, some were contaminated with aflatoxins, and with the caterpillar fungus the identity of the material is fundamentally questionable. For chaga there are no controlled studies in humans, and for sleep there are no reliable human data for any of the mushrooms.

Status, approval and legal

In Germany, medicinal mushrooms are sold as food supplements. For this, a notification to the Federal Office of Consumer Protection and Food Safety (BVL) is sufficient; there is no approval or efficacy testing. No medicinal mushroom is approved as a medicine. In 2015, an expert commission of BVL and BfArM stated that products made from caterpillar fungus, turkey tail and lacquered bracket that are advertised with effects against cancer, rheumatism, impotence or depression are to be regarded as medicines and would then require approval. Healing claims are not permitted for food supplements.

Safety

Most medicinal mushrooms are well tolerated; stomach complaints, headaches and allergic reactions are possible. According to the Verbraucherzentrale, Reishi can lead to dangerous hypoglycemia in people with and without diabetes. Chaga is rich in oxalate; a 2022 case report describes a 69-year-old man who developed acute kidney failure after 3 months of chaga powder. Beta-glucan extracts from mushrooms should not be combined with anti-inflammatory medicines such as cortisone. Anyone taking blood sugar or blood-thinning medication, who has kidney disease or a weakened immune system, or who is pregnant or breastfeeding, should consult a physician beforehand.

Sources

• BVL, press release of February 6, 2015 — medicinal mushrooms classified as medicines
• Verbraucherzentrale (German consumer advice centre) — medicinal mushrooms for cancer therapy?, as of 2025
• Tang W et al., J Med Food 2005 — Reishi polysaccharide extract in neurasthenia, RCT
• Mori K et al., Phytother Res 2009 — lion’s mane in mild cognitive impairment, RCT
• Menon A et al., Front Nutr 2025 — lion’s mane as a supplement, systematic review
• Klupp NL et al., Cochrane Database Syst Rev 2015 — Reishi for cardiovascular risk factors
• Jin X et al., Cochrane Database Syst Rev 2016 — Reishi in cancer treatment
• Shu MY et al., Front Nutr 2025 — mushroom supplements in athletes, meta-analysis
• Parcell AC et al., Int J Sport Nutr Exerc Metab 2004 — Cordyceps in cyclists, RCT
• Kwon O et al., Medicine 2022 — oxalate nephropathy after chaga powder, case report