What are functional mushrooms? A beginner's guide
Functional mushrooms are the ones people take for what they might do for the body and mind. Lion's Mane, Reishi, Cordyceps, Chaga, Maitake and Tremella are the best known. Several of them are also perfectly good to eat, and in parts of East Asia they've been in soups, teas and tonics for centuries.
People often ask whether these are magic mushrooms. They contain no psilocybin, and all of them are legal to buy and sell as food supplements in the UK.
The six you'll see most often
| Mushroom | Latin name | Traditional use | Where the research is |
|---|---|---|---|
| Lion's Mane | Hericium erinaceus | Cooked in Chinese and Japanese kitchens, valued for a clear head | A handful of small human trials on memory, focus and mood |
| Reishi | Ganoderma lucidum | Called lingzhi in China, a calming tonic for over 2,000 years | Mostly animal studies, plus a new human sleep trial presented in 2026 |
| Cordyceps | Cordyceps sinensis | Himalayan and Tibetan tradition, for stamina | A few small human trials on exercise and energy |
| Chaga | Inonotus obliquus | Brewed as tea in Siberia and Scandinavia | Lab studies on its antioxidant compounds |
| Maitake | Grifola frondosa | Japanese cooking and folklore | Animal and lab studies on beta glucans |
| Tremella | Tremella fuciformis | Chinese beauty traditions, eaten in sweet soups | Mostly lab studies on how its polysaccharides hold water |
Maitake translates as "dancing mushroom". The story goes that foragers in Japan danced when they found one, partly because a good cluster can weigh several kilos and partly because it was worth its weight in silver. Whether anyone actually danced is anyone's guess.
What they contain
Most of the interest centres on two groups of compounds.
Beta glucans are long chains of sugar molecules in the mushroom's cell walls. They are the most studied compounds in functional mushrooms, especially Maitake and Reishi. Oats and barley contain beta glucans too, though of a different type.
Triterpenes are bitter compounds found in high amounts in Reishi. They're the reason Reishi tea tastes like tree bark, and they were the part the 2026 sleep trial standardised its extract to.
Each mushroom has its own extras. Lion's Mane contains hericenones and erinacines, which researchers have studied for nerve growth in the lab. Cordyceps contains cordycepin. Tremella's polysaccharides can hold a lot of water, which is where its skin reputation comes from.
How to read a mushroom label
This is where products vary most, and where most people get lost. Four things are worth checking.
1. Extract or powder
Mushroom powder is dried mushroom, ground up. An extract has been soaked in hot water, alcohol or both to pull out the compounds, then dried. Extracts are more concentrated, gram for gram, and the tough cell walls that lock beta glucans away have been broken down.
2. The extract ratio
A ratio like 10:1 or 20:1 tells you how much dried mushroom went into the extract. At 20:1, 20kg of dried Reishi makes 1kg of extract. A higher ratio means more mushroom per gram, though two brands can calculate ratios differently, so it's a guide.
3. Fruiting body or mycelium
The fruiting body is the part you'd recognise as a mushroom. Mycelium is the root like network that grows underground or through wood. Some supplements are made from mycelium grown on rice or oats, and the finished powder can contain a fair amount of that grain. A label that says "fruiting body" or gives a beta glucan percentage tells you more than one that just says "mushroom blend".
4. Amounts
Look for the amount of each mushroom per serving. A "proprietary blend" with one combined weight makes it impossible to know how much of each you're getting.
What the UK allows brands to say
This part surprises people. In the UK, there are no authorised health claims for any functional mushroom. Every health claim on a food or supplement has to be on the Great Britain nutrition and health claims register, and mushrooms aren't on it.
Vitamins and minerals are. That's why many mushroom products, ours included, add a vitamin. Starshroooms contains Vitamin B5 at 200% of the daily reference intake, and Vitamin B5 contributes to the reduction of tiredness and fatigue. It also contains iodine, which contributes to normal cognitive function.
If a mushroom product promises to boost your immune system, sharpen your memory or cure anything, it is breaking the rules, or relying on a vitamin to do the talking without saying so.
Are they safe?
For most healthy adults, the common functional mushrooms have a good safety record at normal amounts. A few points are worth knowing:
- Reishi may affect blood clotting and blood pressure, so check with your GP if you take blood thinners or blood pressure medication.
- Chaga is high in oxalates. People with a history of kidney stones should be careful with large amounts.
- Anyone pregnant, breastfeeding, on medication or awaiting surgery should speak to a GP or pharmacist first.
- Mushroom allergies exist. Stop if you notice a rash, itching or stomach upset.
Where to start
Pick one goal and one product, take it every day for a month, and pay attention to how you feel. Mushroom extracts are usually taken daily over weeks in the studies, so a single dose rarely tells you much.
If you'd like to try several at once, Starshroooms comes as a five day trial pack for £4.99, with Lion's Mane, Reishi, Cordyceps, Chaga, Maitake and Tremella in every blackcurrant gummy. And if you want the detail on each ingredient, the research page links every study we've looked at.
