Reishi (Ganoderma lucidum)
4 pathways by which reishi shows antidepressant activity, including one that produces effects comparable to fluoxetine in animal models
Ganoderma lucidum spore polysaccharide-peptide upregulated hippocampal BDNF with effects comparable to fluoxetine in animal models. A 2024 double-blind RCT confirmed improved depression scores vs placebo in human participants.
Zhao et al., 2021; Mitra et al., 2024
2 human RCTs
showing reishi improves depression or mood outcomes vs placebo
Dectin-1
receptor pathway linking beta-glucan ingestion to hippocampal BDNF expression
Strongest
evidence of any functional mushroom for major depression (Fijałkowska 2022 systematic review)
Zhao et al., 2021; Mitra et al., 2024
View as image ↗In 2024, a double-blind, placebo-controlled trial tested reishi supplementation in female college students experiencing psychological stress. Participants receiving Ganoderma lucidum showed significant improvement on validated measures of perceived stress, anxiety, depression, vitality, and positive well-being compared to placebo.[1] The trial is not the first to find mood benefits from reishi, but it is the most recent and it tested endpoints specific to depression, not just vague wellbeing or sleep quality.
Reishi's antidepressant activity involves four distinct biological pathways, which is unusual for any single supplement and almost completely unreported in consumer content. This article covers what the human trials show, what the animal and mechanistic studies reveal, and where the evidence is still thin. For the foundational overview of what reishi is and its complete pharmacology, see What Is Reishi Mushroom?.
Key Takeaways
- A 2024 double-blind RCT in female college students found reishi supplementation significantly improved validated measures of depression, anxiety, stress, and positive well-being vs placebo.
- A 2020 RCT in fibromyalgia patients found Ganoderma lucidum significantly improved quality of life scores, fatigue, and mood regulation vs placebo.
- Ganoderma polysaccharides activate the Dectin-1 innate immune receptor, which upstream triggers hippocampal BDNF upregulation, the same neurotrophic factor targeted by modern antidepressants.
- Ganoderma spore polysaccharide-peptide reduced depressive behavior in animal models with effects comparable to fluoxetine, an SSRI antidepressant, while also upregulating BDNF and its TrkB receptor.
- Gut microbiota reshaping by reishi polysaccharides increases tryptophan-to-serotonin conversion, a distinct pathway from the GABA mechanism driven by reishi triterpenes.
- A 2022 systematic review found Ganoderma lucidum has the strongest evidence of any functional mushroom for major depression across multiple converging mechanisms.
The Human Trials: What Depression Endpoints Actually Show
Two placebo-controlled trials have measured depression-related outcomes specifically in humans receiving Ganoderma lucidum supplementation.
The Mitra 2024 trial enrolled female college students experiencing psychological stress and assigned participants to either reishi supplementation or placebo in a double-blind design.[1] The outcome measures included validated scales for perceived stress, anxiety, depression, vitality, and positive well-being. Participants in the reishi group showed significant improvement across all five measures compared to placebo. This is a healthy young population, not a clinical depression sample, which matters for interpreting the results: the trial shows mood regulation benefit in non-clinical depression, not treatment of diagnosed major depressive disorder.
The Pazzi 2020 trial tested Ganoderma lucidum supplementation in patients with fibromyalgia, a chronic pain condition with very high rates of comorbid depression and anxiety.[6] This was a randomized controlled trial comparing reishi to placebo. Patients in the reishi group showed significantly improved quality of life scores, fatigue levels, and mood regulation compared to placebo. Fibromyalgia patients represent a population where depression is a genuine clinical concern, not just subclinical stress, making this finding more clinically meaningful than the college student data.
Between the two trials, reishi has now been tested in two distinct human populations with two distinct entry points: subclinical stress in young adults and chronic illness-related depression in middle-aged patients. Both showed improvement vs placebo.
Neither trial is in a large general population sample with diagnosed major depressive disorder. That larger trial has not been done. The human evidence is encouraging and mechanistically coherent but not at the scale required to make clinical claims about treating major depression.
For context on how reishi's evidence compares to other non-psychedelic functional mushrooms for depression, see Functional Mushrooms for Depression: Non-Psychedelic Options.
BDNF Upregulation: How This Pathway Links Reishi to Antidepressant Biology
BDNF stands for brain-derived neurotrophic factor. It is a protein that promotes the growth, maintenance, and survival of neurons, particularly in the hippocampus, the brain region most directly associated with depression. BDNF levels are consistently lower in people with major depressive disorder, and restoring them is a proposed common mechanism for how multiple classes of antidepressant drugs work, including SSRIs.
A 2021 study by Li et al. identified the specific receptor pathway linking reishi polysaccharide ingestion to hippocampal BDNF upregulation.[4] The receptor is Dectin-1, an innate immune receptor expressed on dendritic cells and macrophages that normally recognizes beta-glucan molecules as signals of fungal presence. When reishi polysaccharides activate Dectin-1, a downstream signaling cascade follows that ultimately leads to increased BDNF expression in the hippocampus. In the chronic unpredictable mild stress mouse model, a standard depression model that produces behavioral and neurochemical changes resembling human depression, activating this pathway reduced depressive-like behavior.
The Dectin-1 finding is significant because it provides a specific receptor-level mechanism. Reishi is not generically "anti-inflammatory" or vaguely "neuroprotective." It engages a defined immune receptor that has a defined downstream effect on brain plasticity chemistry. No competitor has covered this pathway, and it is the most mechanistically precise finding in the reishi depression literature.
A separate 2021 study by Zhao et al. tested Ganoderma spore polysaccharide-peptide in depression models.[5] In the forced swim test and tail suspension test, which are standard mouse behavioral depression models, the spore polysaccharide-peptide complex significantly reduced immobility time. The compound also upregulated hippocampal BDNF and its receptor, TrkB. The effects were compared directly to fluoxetine (Prozac), a widely prescribed SSRI antidepressant, and the polysaccharide-peptide complex produced comparable results. This is an animal study, not a human trial, and does not mean reishi works like Prozac in humans. But it does show that the BDNF pathway through which reishi acts is the same pathway targeted by one of the most widely used antidepressant drugs.
For a comparative look at how Lion's Mane's NGF pathway differs from reishi's BDNF mechanism, see Lion's Mane for Depression: How NGF Supports Mood.
The Gut-Serotonin Connection: A Second, Distinct Antidepressant Pathway
Serotonin is a neurotransmitter associated with mood regulation, and low serotonin function is one of the most cited (if contested) biological correlates of depression. Most people assume serotonin is produced in the brain. In fact, approximately 90% of the body's serotonin is produced in the gut, where it regulates intestinal function and is synthesized from tryptophan by gut bacteria.
A 2021 study by Yao et al. found that Ganoderma lucidum treatment reshaped gut microbiota composition in a way that increased tryptophan-to-serotonin conversion in the intestinal tract.[7] Specific bacterial populations that drive this conversion were enriched by reishi polysaccharide intake. In mouse models, this shift extended non-REM sleep and increased intestinal serotonin levels.
This is a mechanistically distinct pathway from the BDNF route. BDNF is upregulated through Dectin-1 signaling. Serotonin is increased through a completely different route: gut microbiome composition change driving enzymatic conversion of a dietary amino acid. These two pathways can operate in parallel and are not in competition.
The gut-serotonin pathway is also distinct from the GABA pathway associated with reishi triterpenes. Reishi's triterpene compounds, including ganoderic acids, act directly on GABA-A receptors in the nervous system. Reishi's polysaccharides take a longer route through the gut. The practical implication: water extracts (higher in polysaccharides) may have stronger gut-microbiota-serotonin activity, while ethanol extracts (higher in triterpenes) may have stronger GABA-mediated calming effects. That distinction is covered in detail in How Reishi Affects GABA and Serotonin Pathways.
Four Antidepressant Mechanisms in One Mushroom: The Lazur 2023 Framework
A 2023 comprehensive review by Lazur et al. mapped four distinct antidepressant mechanisms across functional mushrooms, finding Ganoderma lucidum with evidence across all four.[3]
The four mechanisms are:
1. BDNF upregulation: increasing neuroplasticity in the hippocampus. This is covered above: Dectin-1 → BDNF (Li 2021) and spore polysaccharide-peptide → BDNF comparable to fluoxetine (Zhao 2021).
2. HPA axis normalization: the HPA axis is the body's stress response system (hypothalamus-pituitary-adrenal). Chronic overactivation of this axis, with persistently elevated cortisol, is one of the physiological signatures of depression and stress-related disorders. Reishi has shown effects on HPA axis regulation in animal and preclinical research.
3. Gut microbiota reshaping to increase serotonin: covered above via the Yao 2021 study.
4. Neuroinflammation reduction: elevated inflammatory markers (IL-1β, IL-6, TNF-α) correlate with treatment-resistant depression, and reishi polysaccharides suppress microglial activation and reduce these cytokines. This mechanism is the most technically detailed and has its own dedicated exploration in Reishi and Neuroinflammation-Driven Depression: Microglial Research.
Having evidence across all four pathways is unusual and suggests that reishi's mood effects are unlikely to be explained by any single biological action. This multi-mechanism profile also means that different people may benefit from different pathways depending on their specific depression biology.
The Systematic Review Evidence: How Reishi Ranks Among Mushrooms
A 2022 systematic review by Fijałkowska et al., specifically examining functional mushroom evidence for major depression, found Ganoderma lucidum to have the strongest evidence of any mushroom for this indication.[2] The review assessed evidence across BDNF upregulation, serotonin modulation, and anti-neuroinflammatory activity, finding all three mechanisms converging in reishi research. The review also noted that clinical trials in humans remain limited, which is an honest assessment of where the evidence stands.
The Lazur 2023 review similarly positioned Ganoderma among the most mechanistically well-characterized mushrooms for depression support.[3] Together these two systematic reviews provide the evidence-tier framing that elevates reishi above general "adaptogen" claims: this is not a mushroom people take for vague wellness reasons and observe variable results. There are specific receptors, specific pathways, and consistent direction of effect across multiple lines of evidence.
For the broader comparison across Lion's Mane and reishi specifically, see Lion's Mane and Reishi for Depression: Non-Psychedelic Mood Support Research.
Honest Limitations: What the Human Evidence Actually Covers
The mechanistic picture is compelling. The human evidence is promising but limited by scope.
Two RCTs. Two specific populations. Neither trial enrolled patients with diagnosed major depressive disorder. Neither trial compared reishi to an antidepressant drug. Both were relatively short duration, measuring effects over weeks.
The animal data, while mechanistically informative, involves mouse behavioral models that approximate depression without fully capturing it. The BDNF-fluoxetine comparison in the Zhao 2021 study is compelling but animal studies frequently fail to translate directly to human clinical outcomes.
The gut-serotonin finding from Yao 2021 is also animal data. Human studies confirming that reishi supplementation changes gut microbiota in a way that measurably increases serotonin availability are not yet published.
What the evidence supports: Ganoderma lucidum has a well-characterized set of antidepressant mechanisms, multiple pre-clinical demonstrations of antidepressant activity, and two placebo-controlled human trials showing mood improvement in non-clinical populations. What it does not yet support: a clinical claim that reishi treats major depressive disorder comparable to pharmaceutical antidepressants.
The Bottom Line
Reishi (Ganoderma lucidum) has demonstrated antidepressant activity across four distinct pathways: BDNF upregulation via Dectin-1 receptor signaling, HPA axis normalization, gut microbiota reshaping to increase serotonin production, and neuroinflammation reduction. Two placebo-controlled human RCTs have confirmed mood improvement vs placebo, one in college students and one in fibromyalgia patients. Animal studies show effects comparable to fluoxetine on BDNF-related markers. A 2022 systematic review found reishi has the strongest evidence of any functional mushroom for major depression. The human clinical evidence, while encouraging, has not yet included patients with diagnosed major depressive disorder or comparison to pharmaceutical antidepressants.
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