Last updated: October 2026
Functional mushrooms are non-psychedelic fungi such as lion’s mane, reishi, cordyceps, chaga, turkey tail and shiitake, sold in the UK as powders, capsules and drinks. Most are legal as foods, but no mushroom has an authorised health claim in Great Britain, and the human research is small and early. Lion’s mane has the most promising trials.
You’ll also see them called adaptogenic or medicinal mushrooms. This guide compares the eight you’re most likely to find on UK shelves, explains what the evidence really shows, how to read a label (fruiting body, mycelium, extracts, beta-glucans), the UK rules, and who should avoid them.
Want an easy way to try reishi? Our Reishi Mushroom Adaptogenic Complex is a reishi hot chocolate powder made with reishi mushroom extract, organic cacao, maca, coconut milk powder and coconut sugar. Stir it into warm milk or water. It contains a little natural caffeine from the cacao, so it isn’t caffeine-free. Vegan, made in the UK and third-party lab tested.
What are functional mushrooms?
“Functional mushrooms” is a marketing name for edible and traditional mushrooms taken for wellbeing rather than just as food. The same group is sold as “adaptogenic” or “medicinal” mushrooms.
“Adaptogen” deserves an honest word. It comes from herbal medicine, where it describes plants and fungi said to help the body cope with stress. It isn’t a scientific or regulatory category. Under UK advertising rules a general claim like “functional” or “adaptogenic” has to sit alongside a specific authorised health claim, and there are none for mushrooms themselves. So when you see the word on a pack, read it as a description of tradition, not a promise.
Most of the scientific interest comes from compounds such as beta-glucans (a type of fibre found in mushroom cell walls), triterpenes in reishi, and hericenones and erinacines in lion’s mane.
Lion’s mane is often sold as a nootropic. For the wider picture, see our nootropics UK guide: what they are, what is legal and what the evidence shows.
Interest in the UK is growing but still niche. In a 2024 YouGov survey of 2,009 adults in Great Britain, 18% had heard of lion’s mane, 7% cordyceps, 3% reishi, 2% tremella and 1% chaga, and 44% said they would be interested in eating mushrooms for health and wellbeing.
They are a completely different thing from psychedelic “magic” mushrooms, which contain psilocybin and are a Class A drug in the UK. Functional mushrooms aren’t psychoactive.
The FSA’s 10mg a day figure for CBD is precautionary advice rather than a legal limit, set while longer-term safety research continues. At Evopure we think it is a very cautious figure, and many adults use more. If you go above it, increase slowly, and check with your GP or pharmacist first if you take any medication.
8 functional mushrooms compared
Here is what each one is studied for, how strong the human evidence really is, what form and amount the trials used, and the one safety point to know. Each has a detailed guide.
| Mushroom | Studied for | Human evidence (honest) | Form and amount in studies | Key safety point | Our guide |
|---|---|---|---|---|---|
| Lion’s mane (Hericium erinaceus) | Memory, focus, mood | Limited but the most promising: two small placebo-controlled trials | Dried fruiting body powder, 1.8g to 3g a day | No adverse effects found on lab tests in the main 16-week trial; avoid with a mushroom allergy | Lion’s mane guide |
| Reishi (Ganoderma lucidum) | Fatigue, wellbeing, immune markers | Limited: one trial on fatigue; Cochrane reviews found too little evidence for cancer or heart risk factors | Extracts, roughly 1.4g to 5.4g a day | Rare liver injury reports with reishi powder; may raise bleeding risk | Reishi guide |
| Cordyceps (Cordyceps sinensis, C. militaris) | Exercise and energy | Mixed: one small positive trial in older adults, no effect in trained cyclists | Cs-4 extract, 1g to 3g a day | Some species, such as C. militaris, are likely unauthorised novel foods in GB | Cordyceps guide |
| Chaga (Inonotus obliquus) | Antioxidants, traditional tea | Very weak: almost no human trials | Tea or powdered extract | Very high in oxalate; kidney damage case reports | Chaga guide |
| Turkey tail (Trametes versicolor) | Immune function alongside cancer treatment | Moderate for one medicine: the extract PSK is approved in Japan as an add-on to cancer treatment; supplement evidence is early | PSK or mushroom preparation, 3g to 9g a day | Likely an unauthorised novel food in GB; not a cancer treatment on its own | Turkey tail guide |
| Shiitake (Lentinula edodes) | Immune markers, food | Weak: one 4-week eating trial with no placebo group | 5g to 10g dried shiitake a day, cooked | Raw or undercooked shiitake can cause a whip-like rash | Shiitake guide |
| Maitake (Grifola frondosa) | Immune markers, blood sugar | Weak: mostly lab and animal work; one small safety trial | Liquid extract dosed by body weight | Immune effects went up and down depending on dose | Maitake guide |
| Tremella (Tremella fuciformis, snow fungus) | Memory, skin | Weak: one 8-week trial in 75 people | Extract, 600mg or 1,200mg a day | Side effects no more common than placebo in that trial | Covered on this page |
Deciding between the three best known? See lion’s mane vs reishi vs cordyceps. Curious how reishi compares with a herbal adaptogen? Read reishi vs ashwagandha.
Do they work? The human evidence
Short answer: a few small trials are interesting, but none of these mushrooms is proven to treat or prevent any condition. Here is what the best human studies found.
- Lion’s mane: in 30 Japanese adults aged 50 to 80 with mild memory decline, 3g a day for 16 weeks improved cognitive scores compared with placebo; the effect faded within four weeks of stopping. A UK pilot at Northumbria University in 41 healthy adults aged 18 to 45 found faster performance on one attention task an hour after 1.8g, and a trend towards lower stress after 28 days, alongside some null results.
- Reishi: in 132 people with long-term fatigue (neurasthenia), a reishi polysaccharide extract for 8 weeks improved symptoms more than placebo. Cochrane reviews found the trials too few and too weak to support reishi as a cancer treatment or for blood sugar, blood pressure or cholesterol in type 2 diabetes. More in reishi for sleep.
- Cordyceps: in 20 adults aged 50 to 75, 12 weeks of a Cs-4 extract improved some exercise thresholds, but a 5-week trial in 22 trained cyclists found no effect on endurance. See adaptogens for energy.
- Tremella: in 75 Korean adults with self-reported memory complaints, an extract for 8 weeks improved memory questionnaire scores more than placebo.
- Shiitake: in 52 healthy young adults, eating 5g or 10g of dried shiitake daily for four weeks changed some markers of immune cell activity. There was no placebo group.
- Turkey tail and maitake: the human research is mostly in people with cancer, using specific extracts alongside medical treatment. That tells you little about a shop-bought supplement. See mushrooms for inflammation for how these studies are often overstated.
- Chaga: very little good human research.
Independent reviewers reach a similar view. The US National Cancer Institute says no medicinal mushroom is approved by the FDA to treat any condition, and Which? concluded in 2025 that there isn’t good evidence for solid health claims for most popular functional mushrooms. Treat them as part of a healthy routine, not a cure for anything. If stress or low mood is your reason for looking, our guide to mushrooms for anxiety and low mood goes through the evidence honestly.
Fruiting body, mycelium and extracts: what the label means
Two packs can both say “1,000mg lion’s mane” and be very different products. Three things on the label tell you what you’re actually getting.
Fruiting body or mycelium?
The fruiting body is the mushroom you can see and pick. The mycelium is the root-like network that grows underneath. Commercial mycelium is often grown on grain such as rice or oats, and the finished powder can include that grain, which is mostly starch. Most of the human trials above used fruiting bodies or named extracts, so a product that doesn’t say which part it uses is hard to compare with the research.
Beta-glucans, not “polysaccharides”
Beta-glucans are the fibre-like compounds most studied in mushrooms. A general “polysaccharides” figure can include alpha-glucans such as starch from grain. Lab methods developed for mushroom and mycelium products measure total glucan and alpha-glucan separately and work out beta-glucan as the difference, which is why a stated beta-glucan percentage tells you far more than a polysaccharide one.
Extracts and ratios
An extract concentrates the mushroom, usually with hot water, alcohol or both. A ratio such as 10:1 describes how much dried mushroom went into each gram of extract; it doesn’t tell you the beta-glucan content. Look for both the ratio and a tested beta-glucan figure.
UK rules: novel foods and health claims
People search for a “functional mushroom ban” in the UK. There isn’t a blanket ban, but two sets of rules matter.
- Novel foods. A food that wasn’t eaten to a significant degree in the UK or EU before 15 May 1997 is a novel food, and it needs authorisation before it can be sold in Great Britain. The Advertising Standards Authority has said turkey tail and some cordyceps species, such as Cordyceps militaris, are likely to be treated by the Food Standards Agency as unauthorised novel foods. Status can depend on the species and the form sold, so if in doubt, ask the seller.
- Health claims. Any health claim on a food in Great Britain must be on the GB Nutrition and Health Claims Register. We checked the register: it has no authorised health claim for any mushroom, and claims submitted for shiitake, cordyceps and reishi are listed as non-authorised. That’s why responsible brands describe ingredients and research rather than promising effects.
- Medicinal claims. Saying a food prevents, treats or cures a disease is only allowed for medicines licensed by the MHRA. A mushroom supplement that claims to treat anxiety, cancer or anything else is breaking the rules.
- Magic mushrooms are a separate matter: they are a Class A drug and illegal to possess, give away or sell.
How to choose a functional mushroom in the UK
Use this checklist before you buy:
- The species is named, ideally with its Latin name (Hericium erinaceus, Ganoderma lucidum and so on).
- The part is stated: fruiting body, mycelium, or both. If it’s mycelium, check whether the grain is included.
- Extract and beta-glucan content are given per serving, not just “1,000mg mushroom”.
- The amount per serving is in the same ballpark as the studies, which used roughly 1g to 3g a day for most mushrooms.
- Third-party testing for heavy metals and contaminants, as mushrooms absorb them from where they grow. Ask to see the reports.
- No disease claims. A brand saying its mushroom treats or cures a condition is breaking UK advertising rules, which says something about the rest of its labelling.
- Novel food status: be wary of turkey tail and Cordyceps militaris products sold in Great Britain unless the seller can show they are authorised.
- A format you’ll actually use every day: capsules, powders or a drink.
Not sure which mushroom to start with? This is how people commonly use them. It’s based on popular use and early research, not proven effects.
| If you’re interested in… | People often choose | When |
|---|---|---|
| Focus for the working day | Lion’s mane | Morning |
| An evening wind-down ritual | Reishi | Evening |
| Something before exercise | Cordyceps | Morning or pre-workout |
| More mushrooms in your diet | Shiitake, maitake | Cooked, with meals |
Start with one, take it daily for at least four weeks, then decide. For a full buyer’s guide, see the best mushroom supplement in the UK.
Our reishi drink
We make one mushroom product: the Reishi Mushroom Adaptogenic Complex, a hot chocolate powder made with organic cacao, reishi mushroom extract (Ganoderma lucidum), maca root extract, coconut milk powder and organic coconut sugar. You stir 1 to 2 teaspoons (4g to 8g) into warm, not boiling, milk or water, and a pouch makes around 30 servings. It is vegan, made in the UK and third-party lab tested, with no artificial sweeteners or flavourings.
Two things to know. Cacao naturally contains a little caffeine, so it isn’t caffeine-free; if you’re sensitive, have it earlier in the evening. And like all our products it is for adults only, and we don’t recommend it during pregnancy or breastfeeding. Read more about reishi cacao and the maca root in it. Stocking up? Our sale runs 27 to 30 November: see our Black Friday supplement deals.
Mushroom coffee, tea and hot chocolate
Many people meet functional mushrooms in a mug rather than a capsule. The amount of mushroom per cup varies widely, so check the label as above.
- Mushroom coffee is usually coffee blended with lion’s mane, chaga or cordyceps. It still contains caffeine from the coffee. Our mushroom coffee guide looks at whether it’s worth it.
- Mushroom tea is the traditional way to take reishi and chaga: dried mushroom simmered in water. See how to make mushroom tea.
- Reishi hot chocolate pairs reishi’s bitter taste with cacao. Cacao contains theobromine and a little caffeine; more in dark chocolate benefits. It also makes a good alcohol-free nightcap.
Safety and who should avoid them
Most healthy adults tolerate functional mushrooms well in the short trials, but they are not risk-free. Talk to your GP or pharmacist first if any of these apply.
- Pregnancy and breastfeeding: there isn’t enough safety data, and we don’t recommend our products during pregnancy or breastfeeding.
- Children: our products are for adults (18+) only.
- Blood thinners and surgery: reishi may increase the risk of bleeding, so check with your pharmacist if you take warfarin or other blood thinners, and tell your surgical team if you have an operation coming up.
- Immunosuppressants: reishi can enhance immune responses, and maitake extract both raised and lowered immune markers in a trial. If you take medicines that dampen the immune system, such as after a transplant, check first.
- Diabetes or blood pressure medicines: check with your pharmacist before adding a mushroom supplement.
- Liver: reishi powder has rare case reports of liver injury, including a fatal case in Thailand and a case linked to reishi with alcohol in the US. In both of the first reports, people had taken boiled reishi safely before switching to powder.
- Kidneys: chaga is very high in oxalate and has been linked with kidney damage in case reports, after daily powder for 3 to 6 months. Avoid it if you’ve had kidney stones or kidney problems. See chaga side effects.
- Raw or undercooked shiitake can cause an itchy, whip-like rash. French poison centres recorded 59 cases between 2014 and 2019; all recovered.
- Cancer treatment: don’t add mushroom extracts alongside chemotherapy or radiotherapy without asking your cancer team.
- Mushroom allergy: avoid all of them.
- Never forage for medicinal mushrooms unless you’re an expert. Some poisonous species look similar.
Related guides
- Wondering about menopause? Read what the evidence says on mushrooms for menopause, including whether they affect oestrogen.
- Gummies are now one of the most popular formats; our mushroom gummies guide covers what to check on the label.
- Reishi also turns up in serums and creams: see reishi mushroom benefits for skin for what the research actually tested.
- DIRTEA: what’s in its mushroom drinks and gummies.
- Rheal Superfoods: which blends contain mushrooms.
- Looking at a specific brand? See Four Sigmatic: ingredients, caffeine and UK availability.
- For what one UK shop stocks, see lion’s mane at Holland and Barrett.
- For a worked example of extracts versus whole powders, read Hifas da Terra: mushroom supplements explained.
- For reishi specifically, see which reishi form to choose, from whole powder to dual extract tinctures.
- Several of these mushrooms appear together in 10-in-1 gummies; see what’s in Ankhway mushroom gummies.
FAQs
What are adaptogenic mushrooms?
Non-psychedelic mushrooms such as lion’s mane, reishi, cordyceps, chaga, turkey tail, shiitake and maitake, taken as supplements or drinks. “Adaptogen” is a traditional term, not a scientific category.
What is the most powerful adaptogenic mushroom?
None has been proven more powerful than the others. Lion’s mane has the most promising human trials, for memory in older adults.
Are adaptogenic mushrooms psychedelic?
No. Functional mushrooms contain no psilocybin and aren’t psychoactive. Psilocybin mushrooms are a Class A drug in the UK.
Are functional mushrooms legal in the UK?
Most are. Lion’s mane, reishi, chaga and shiitake are sold as foods and food supplements. Some types, such as turkey tail and Cordyceps militaris, are likely to be unauthorised novel foods in Great Britain, and no mushroom has an authorised health claim.
Can you take several adaptogenic mushrooms together?
Healthy adults usually can. Add one at a time, and split them by time of day, such as lion’s mane in the morning and reishi in the evening.
How long do adaptogenic mushrooms take to work?
Most trials ran for 4 to 16 weeks. Take one daily for at least four weeks before judging it.
Are functional mushrooms safe?
For most healthy adults they are well tolerated in short trials. Avoid them in pregnancy and breastfeeding, and check with your GP or pharmacist if you take blood thinners, immunosuppressants, diabetes or blood pressure medicines. Reishi powder has rare liver case reports, and chaga is very high in oxalate.
Is there a functional mushroom ban in the UK?
No blanket ban. But foods without a history of use before May 1997 need novel food authorisation, and turkey tail and some cordyceps species are likely to be treated as unauthorised novel foods in Great Britain.
Is fruiting body or mycelium better?
Most human trials used fruiting bodies or named extracts. Mycelium grown on grain can include a lot of starch, so look for a product that states the part used and a tested beta-glucan content.
Do functional mushrooms contain caffeine?
Mushrooms themselves don’t. Mushroom coffee does, from the coffee, and reishi hot chocolate contains a little natural caffeine from the cacao.
What is the best functional mushroom to start with?
Pick one that matches how you’ll use it: lion’s mane is the most studied for focus and memory, reishi suits an evening routine, and cordyceps is popular before exercise. Start with one and give it four weeks.
Sources
- Food Standards Agency. Novel foods authorisation guidance. GOV.UK.
- Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. GOV.UK (checked October 2026).
- CAP/ASA. Shroom for improvement? Navigating the advertising rules for functional mushrooms. November 2024.
- GOV.UK. Drugs penalties.
- Which?. What are functional mushrooms and do they really have health benefits? November 2025.
- YouGov. Are Britons interested in “functional” mushrooms? March 2024.
- National Cancer Institute. Medicinal mushrooms (PDQ).
- Memorial Sloan Kettering Cancer Center. Reishi mushroom: About Herbs.
- Mori K et al. Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment. Phytother Res, 2009. PMID 18844328.
- Docherty S et al. The acute and chronic effects of lion’s mane mushroom supplementation on cognitive function, stress and mood in young adults. Nutrients, 2023. PMID 38004235.
- Tang W et al. A Ganoderma lucidum polysaccharide extract in neurasthenia. J Med Food, 2005. PMID 15857210.
- Jin X et al. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane Database Syst Rev, 2016. PMID 27045603.
- Klupp NL et al. Ganoderma lucidum mushroom for the treatment of cardiovascular risk factors. Cochrane Database Syst Rev, 2015. PMID 25686270.
- Chen S et al. Effect of Cs-4 (Cordyceps sinensis) on exercise performance in healthy older subjects. J Altern Complement Med, 2010. PMID 20804368.
- Parcell AC et al. Cordyceps sinensis (CordyMax Cs-4) supplementation does not improve endurance exercise performance. Int J Sport Nutr Exerc Metab, 2004. PMID 15118196.
- Ban S et al. Efficacy and safety of Tremella fuciformis in individuals with subjective cognitive impairment. J Med Food, 2018. PMID 29319408.
- Dai X et al. Consuming Lentinula edodes (shiitake) mushrooms daily improves human immunity. J Am Coll Nutr, 2015. PMID 25866155.
- Torkelson CJ et al. Phase 1 clinical trial of Trametes versicolor in women with breast cancer. ISRN Oncol, 2012. PMID 22701186.
- Deng G et al. A phase I/II trial of a polysaccharide extract from Grifola frondosa (maitake mushroom) in breast cancer patients. J Cancer Res Clin Oncol, 2009. PMID 19253021.
- McCleary BV, Draga A. Measurement of beta-glucan in mushrooms and mycelial products. J AOAC Int, 2016. PMID 26957216.
- Yuen MF et al. Hepatotoxicity due to a formulation of Ganoderma lucidum (lingzhi). J Hepatol, 2004. PMID 15464254.
- Wanmuang H et al. Fatal fulminant hepatitis associated with Ganoderma lucidum (lingzhi) mushroom powder. J Med Assoc Thai, 2007. PMID 17621752.
- Guedikian R et al. Ganoderma lingzhi (reishi mushroom)-induced acute liver injury in the setting of alcohol use. Cureus, 2023. PMID 37885515.
- Kikuchi Y et al. Chaga mushroom-induced oxalate nephropathy. Clin Nephrol, 2014. PMID 23149251.
- Kwon O et al. Chaga mushroom-induced oxalate nephropathy that clinically manifested as nephrotic syndrome: a case report. Medicine, 2022. PMID 35451393.
- Boels D et al. Shiitake dermatitis: experience of the Poison Control Centre Network in France from 2014 to 2019. Clin Toxicol, 2022. PMID 35404185.
