Reishi is one of those ingredients that comes with a reputation before most people ever look at the research. You will see it described as the mushroom for calm, stress, sleep, immunity and balance, sometimes all in the same paragraph. It has also been used in traditional Asian medicine for a very long time, so it carries considerably more history than many newer functional-food ingredients.
That combination makes Reishi interesting, but it also makes it very easy to oversimplify. When I started looking more closely at the research, I expected there to be a fairly straightforward explanation for why Reishi had become associated with calm. What I found was much messier. There are human studies, and there is a meaningful body of research around Ganoderma, but the evidence does not line up neatly behind the way Reishi is often marketed.
What is Reishi?
Reishi generally refers to mushrooms in the Ganoderma group. You may also see the name Lingzhi used, particularly when reading about its history in China and other parts of Asia. The mushroom itself develops a glossy, lacquered-looking surface and is usually reddish-brown. Unlike an ordinary culinary mushroom that you might slice into dinner, Reishi has traditionally been prepared in teas, decoctions and extracts because of its tough texture.
Researchers have investigated many compounds found in Ganoderma, particularly polysaccharides such as beta-glucans and a group of triterpenes commonly referred to as ganoderic acids. That gives scientists plenty to study. The harder question is what those compounds actually mean when people consume Reishi.
There is more human research than you might expect
Reishi is not a case where all of the evidence comes from test tubes and mice. A 2025 systematic review and meta-analysis pulled together 17 randomized controlled trials involving 971 people. The studies covered different populations, different doses and intervention periods ranging from one to 24 weeks.
Researchers found statistically significant changes in a few measures, while many other outcomes showed no significant overall effect. Then comes the part I think matters most: the authors rated the certainty of the evidence as very low across all of the outcomes they assessed. That does not mean Reishi does nothing. It means the current clinical literature is not strong enough to support the certainty that often appears in Reishi advertising.
What about stress and calm?
This is probably the biggest disconnect between how Reishi is marketed and what the research can currently tell us. Reishi is very commonly positioned as a calming mushroom, and you will see language suggesting it helps the body deal with stress, promotes relaxation or supports sleep.
Those ideas may partly reflect Reishi's long history of traditional use and partly reflect modern laboratory research into its various compounds. What we do not have is strong clinical evidence showing that a normal serving of Reishi mushroom coffee reliably makes people calmer or improves sleep.
That distinction matters for Urban Calm because Centered contains Reishi, and our brand name already puts the word Calm right there on the bag. I do not think we need to pile another promise on top of it. Centered can be a medium roast with Chaga and Reishi, and someone can enjoy making it part of a quieter morning ritual, without us telling them the mushroom has been clinically proven to reduce stress.
Traditional use and clinical proof are different kinds of information
I do think traditional use deserves respect. When an ingredient has been used for generations, that history is worth understanding. It can also help researchers decide what questions are worth studying. But traditional use and modern clinical evidence answer different questions.
Traditional practice tells us that people have valued and used Reishi over long periods of time. A randomized controlled trial asks whether a defined preparation causes a measurable effect under specific conditions. Neither one needs to be dismissed. They just should not be presented as though they are the same thing.
Preparation matters here too
The 17 trials in the 2025 analysis were not all testing one identical Reishi ingredient. Research may use extracts, powders, spores, fruiting bodies, mycelium or other preparations, and doses can vary enormously. The meta-analysis included interventions ranging from 200 mg to 11,200 mg per day. That is another reason a study on Reishi cannot automatically be converted into a claim about Reishi coffee. The mushroom name is only the beginning of the ingredient description.
How Urban Calm uses Reishi
We use Reishi in two blends. Centered is our medium roast and pairs Reishi with Chaga. Dreamer is our dark roast and pairs Reishi with Lion's Mane. I like this pairing because it also shows why I do not want the mushrooms to become the only way people choose the coffee.
If you are interested in Reishi, you still have two very different cups in front of you. Centered is the more balanced medium roast. Dreamer goes deeper and darker. Choose the coffee you actually want to drink. The Reishi is already part of both.
So why is Reishi still interesting?
Because the evidence is not settled and there is nothing to study are not the same statement. Reishi has a long history of use, a complicated chemistry and a larger human research base than many people probably realize. The problem is that the current studies are inconsistent and often too small or too different from one another to support the confidence of the marketing around them.
That is a perfectly reasonable place for the science to be. I do not need Reishi to have a magical one-word promise for it to be worth including in a thoughtful mushroom coffee. For Urban Calm, I would rather tell you what it is, tell you why people are interested in it and be clear about what we still do not know. Then let the coffee speak for itself.
Keep learning
- Fruiting Body vs. Mycelium
- Lion's Mane in Mushroom Coffee
- How to Choose Your Mushroom Coffee Roast
- Explore Urban Calm Mushroom Coffee
