Reishi has been used for centuries and is now one of the most recognizable functional mushrooms in supplements, teas and mushroom coffee. It is also marketed with a long list of promises around stress, fatigue, immunity and general well-being.
The human evidence is more interesting, and more limited, than those promises can make it sound.
This article takes a narrower look at Ganoderma lucidum, also known as Reishi or Lingzhi: what selected human trials actually found, how long participants took the studied preparations, where results have been disappointing, and why “consistent use” needs to be understood carefully.
For a broader introduction to the ingredient, start with Reishi in Mushroom Coffee: What We Know, What We Don't and How Urban Calm Uses It.
Human Reishi research is not one single body of evidence
One of the most important things to understand about Reishi research is that the studies do not all test the same thing.
Human trials have used polysaccharide extracts, spore powders and other Ganoderma preparations at different amounts, in different populations, for different lengths of time. A result from one preparation cannot automatically be transferred to every Reishi product on the market.
That matters especially when discussing mushroom coffee. A clinical trial using several grams of a specific extract or spore preparation is not the same intervention as an ordinary serving of coffee containing Reishi extract.
The strongest fatigue signal: an eight-week Ganopoly trial
One of the better-known randomized, double-blind, placebo-controlled human trials studied a Reishi polysaccharide extract called Ganopoly in 132 people diagnosed with neurasthenia, a condition that included persistent physical and mental fatigue and related symptoms.
Participants received either placebo or 1,800 mg of Ganopoly three times per day, for a total of 5.4 grams daily, over eight weeks.
Among the 123 participants included in the efficacy analysis, the Ganopoly group showed larger improvements than placebo in several measures. Clinical Global Impression severity scores fell 15.5% in the Ganopoly group compared with 4.9% with placebo. Fatigue scores fell 28.3% versus 20.1%, and sense-of-well-being scores improved 38.7% versus 29.7%. Just over half of the Ganopoly group was rated more than minimally improved, compared with about one quarter of the placebo group.
Read the original study: Tang et al., 2005.
Those results are worth paying attention to. They are not, however, evidence that every Reishi product reduces fatigue. The trial used a specific high-dose extract in a specific patient population for eight continuous weeks. The preparation, amount and population all limit how far the findings can be generalized.
A four-week cancer-related fatigue pilot: promising, but highly specific
Another human study looked at Reishi spore powder in 48 breast cancer patients experiencing fatigue while receiving endocrine therapy. Participants took 1,000 mg three times daily, or 3 grams per day, for four weeks.
The Reishi group reported improvements in physical well-being, fatigue and several quality-of-life measures compared with placebo. Researchers also reported lower levels of the inflammatory markers TNF-alpha and IL-6 after treatment. No serious adverse effects were reported in the study, although mild dizziness and dry mouth occurred in some participants.
Read the original study: Zhao et al., 2012.
This study is interesting, but its context is essential. It involved people undergoing cancer treatment, tested a Reishi spore powder rather than mushroom coffee, and was a small four-week pilot. It should not be converted into a claim that Reishi coffee treats cancer-related fatigue, anxiety, depression or inflammation.
Where the evidence is less convincing
Not every well-designed human trial has produced a positive result.
A double-blind, randomized, placebo-controlled trial in adults with type 2 diabetes and metabolic syndrome tested Ganoderma lucidum preparations for 16 weeks. Researchers measured HbA1c, fasting glucose, blood pressure, triglycerides, waist circumference, BMI and lipid markers.
The study did not find clinically meaningful benefits on its primary or secondary outcomes. Treatment effects were generally close to zero. A Cochrane review examining Reishi for cardiovascular risk factors in people with type 2 diabetes similarly concluded that the available evidence did not support its use for those outcomes.
Read the 16-week randomized trial and the Cochrane review.
This negative evidence is useful. It shows why a balanced discussion of Reishi cannot simply collect the positive studies and ignore trials that found little or no effect.
Immune and inflammatory markers are not the same as a guaranteed health outcome
Some human studies, especially in oncology settings, have reported changes in immune cell populations, cytokines and inflammatory or oxidative-stress markers after Reishi preparations.
Those biological signals can help researchers understand what an ingredient may be doing. But a change in a laboratory marker is not automatically the same thing as a meaningful everyday benefit, and findings in patients receiving medical treatment should not be generalized casually to healthy coffee drinkers.
The human data outside those specialized populations remain limited, and the Reishi preparations used across studies vary considerably.
Why consistency matters in the studies, and what that does not mean
There is a clear pattern in the human research that reported positive changes: participants did not take Reishi once in a while.
The neurasthenia trial used daily intake for eight weeks. The breast cancer fatigue pilot used daily intake for four weeks. Other research examining cardiovascular and inflammatory markers has used daily intake for months.
That makes consistency important when interpreting the research. If a study gave a preparation every day for several weeks, its outcome cannot tell us what would happen with occasional use.
But this point needs an equally important qualification: the studies do not establish a universal rule that everyone needs to take Reishi every day, and they do not prove that a daily cup of Reishi mushroom coffee will reproduce the results of gram-level clinical protocols.
The more accurate conclusion is that the positive trials studied sustained exposure rather than sporadic use. That is different from promising that “daily use” guarantees a benefit.
For a broader discussion of everyday mushroom coffee use, read Can You Drink Mushroom Coffee Every Day?.
How Reishi fits into Urban Calm's coffee lineup
Urban Calm uses Reishi in two mushroom coffee blends:
- Centered Medium Roast pairs Reishi with Chaga.
- Dreamer Dark Roast pairs Reishi with Lion's Mane.
Both use organic 100% fruiting body mushroom extracts with no mycelium-based mushroom ingredients, and Urban Calm's mushroom extracts are third-party tested.
Those product-quality choices matter, but they do not make Urban Calm's coffee equivalent to the Ganopoly extract, Reishi spore powder or other preparations used in clinical trials. We think that distinction is important enough to say plainly.
If Reishi is part of someone's routine, coffee can be a familiar and easy way to use it consistently. The reason Urban Calm puts the coffee first is equally simple: a routine only works if you actually enjoy it.
Explore Centered Medium Roast, Dreamer Dark Roast, or compare the full mushroom coffee collection.
What do human studies tell us about safety?
Across several small, short-term human trials, Reishi preparations have generally been well tolerated. Mild effects such as dizziness and dry mouth have been reported, while serious adverse events were uncommon in the trials summarized in the research.
There is an important exception to keep in perspective. The U.S. National Library of Medicine's LiverTox review notes a small number of case reports of acute liver injury associated with Lingzhi or Reishi products. Given the extent of worldwide use, clinically apparent liver injury is considered rare, but the possibility has not been ruled out.
Read the LiverTox review of Lingzhi and Reishi.
People with liver disease, autoimmune conditions or complex medication regimens should discuss prolonged use of functional mushroom products with a qualified healthcare professional.
The bottom line on Reishi benefits
Reishi has real human research behind it, but the evidence is not a straight line from “studied” to “proven.”
Some small trials have reported improvements in fatigue, well-being, quality of life and selected immune or inflammatory markers. Other rigorous research, particularly around metabolic and cardiovascular outcomes, has found little or no meaningful effect.
The studies that reported benefits generally used specific preparations at substantial daily amounts for several weeks or months. That makes duration and consistency part of the evidence, but it does not establish a universal daily dose or guarantee that a commercial food product will produce the same outcome.
For us, the useful position is somewhere between hype and dismissal: Reishi is an interesting functional mushroom with developing human evidence, and it can fit naturally into a coffee routine without pretending that coffee is medicine.
Want the broader ingredient overview? Read Reishi in Mushroom Coffee or compare it with Lion's Mane, Reishi, Chaga and Cordyceps.
This article is educational and is not medical advice.
