Also known as: Ganoderma lucidum, Lingzhi, Mushroom of immortality, Triterpenes, Beta-glucans
BotanicalEmerging evidence
A woody bracket fungus with a long history in East Asian practice, used for sleep and calm rather than energy. As with all medicinal mushrooms, fruiting body versus mycelium on grain is the question that decides what you actually get.
Typical dose
1.0–3.0 g per day
Evening, with or without food
What it is
Reishi is the fruiting body of Ganoderma lucidum, a hard, glossy, kidney-shaped bracket fungus that grows on hardwood. Known as lingzhi in China, it holds a prominent place in traditional East Asian practice and appears in art going back centuries.
Two compound groups matter: beta-glucans, the polysaccharides common to medicinal mushrooms, and triterpenes, which are more specific to reishi and give it its distinctly bitter taste. A reishi product that is not bitter probably contains very few triterpenes.
The quality problem is the same one that affects the whole mushroom category. Much of the market supplies mycelium grown on a rice or oat substrate and sold with the substrate included, meaning a large share of product weight can be starch. Beta-glucan content is the honest quality marker; total polysaccharide figures can be inflated by that starch. Dual extraction matters here too, since triterpenes are alcohol-soluble and beta-glucans water-soluble.
How it works
Beta-glucans interact with receptors on immune cells, modulating rather than simply boosting immune activity. This is the mechanism common to medicinal mushrooms generally.
The triterpenes are more distinctive to reishi and are credited with its calming quality, with reported effects on the nervous system that fit its traditional use as an evening rather than morning preparation.
Antioxidant activity and effects on liver enzymes have also been described. As with most traditional fungal preparations, the mechanistic picture is broad rather than deep, and human confirmation lags well behind the laboratory work.
What the evidence shows
Human evidence is limited. The strongest area concerns fatigue and wellbeing measures, where a small number of controlled trials have reported improvements in self-reported fatigue over several weeks.
Sleep research is largely preclinical, with animal work reporting increased sleep duration. Human trials specifically on sleep quality are scarce, which is worth knowing given how reishi is usually marketed.
Immune marker studies have reported changes in immune cell activity, though whether those translate into anything a person would notice is unestablished. The overall picture is a well-regarded traditional preparation with a thin human evidence base and a considerable amount of laboratory work behind it.
Dosing
Common supplemental range is 1-3 g daily of extract, usually taken in the evening given its calming reputation.
Assess products on three points before comparing doses: fruiting body or mycelium on grain, declared beta-glucan percentage, and whether the extract is dual-extracted. A gram of dual-extracted fruiting body with stated beta-glucan content is not comparable to a gram of mycelium-on-grain powder.
Effects reported in trials accrue over several weeks of consistent use. Reishi is genuinely bitter, which is a reasonable sign the triterpenes are present.
At a glance
Common forms
Dual-extracted fruiting body, Hot water extract, Mycelium on grain, Spore oil, Capsules and powder
Half-life / duration
Not well characterised; effects accrue over weeks
Timing
Evening, with or without food
Competition status
Permitted — not on the WADA Prohibited List
Category
Botanical
Safety and side effects
Generally well tolerated, with digestive upset, dry mouth and occasional dizziness the most commonly reported effects. Reishi has a long record of traditional use.
It has immune-modulating activity and a mild effect on how readily blood clots. Check with your doctor before use if you take regular medication or if your immune system is being managed.
Anyone sensitive to fungi or moulds should avoid it. Long-term data at concentrated extract doses is limited.
Who should avoid it
Speak to your doctor before use if you take regular medication, particularly anything affecting blood clotting, or if your immune system is being managed. Avoid if sensitive to fungi or moulds. Stop before scheduled surgery. Not established for use in pregnancy or breastfeeding.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
