Cortisol is often referred to as the “stress hormone”, but it is an essential hormone involved in energy metabolism, immune system regulation, blood pressure maintenance, and the body’s response to physical and emotional stress.

What matters is not only the amount of cortisol, but also its normal circadian rhythm and the body’s ability to return to physiological balance after stress.

Chronic stress can affect sleep quality, nervous system function, oxidative balance, inflammatory processes, and the body’s hormonal stress response.

It is in this context that researchers are increasingly interested in Reishi (Ganoderma lucidum) and its biologically active compounds — polysaccharides, beta-glucans, triterpenoids, and ganoderic acids.

These compounds are being studied in relation to several interconnected processes that may help support the body’s normal response to physiological stress and overall physiological balance.

What Is Cortisol and Why Does the Body Need It?

Cortisol is produced by the adrenal cortex, and its secretion is regulated by the hypothalamic–pituitary–adrenal (HPA) axis.

Under normal conditions, cortisol levels fluctuate throughout the day. They are generally higher in the morning and gradually decrease as the day progresses.

During stress, the HPA axis becomes activated. The pituitary gland releases adrenocorticotropic hormone (ACTH), which in turn stimulates the adrenal cortex to release cortisol.

This response is normal and necessary — it helps the body adapt to increased demands.

Therefore, the goal is not simply to “lower cortisol”. More important is maintaining a normal stress response, a healthy circadian cortisol rhythm, and the ability to return to a balanced state after stress.

Reishi and Stress – What Could the Connection Be?

Reishi mushroom (Ganoderma lucidum) attracts scientific interest because its bioactive compounds are being studied in relation to multiple physiological processes rather than one isolated mechanism.

Reishi and its compounds are being investigated in connection with:

• oxidative stress regulation mechanisms;
• the body’s antioxidant defence;
• immune system function;
• inflammatory signalling mechanisms;
• the nervous system and sleep;
• the gut microbiome and gut–brain interactions.

All of these processes are, to varying degrees, associated with the body’s response to prolonged physiological stress.

For this reason, Reishi extract is of interest as a source of bioactive compounds in the context of supporting the body’s adaptation and normal stress response.

Reishi, Cortisol and the HPA Axis

Research into bioactive compounds from medicinal mushrooms also examines their potential relationship with HPA axis activity, ACTH and cortisol regulation.

Studies that simultaneously assess several markers of stress physiology — including cortisol, ACTH, sleep quality, fatigue and perceived stress — are particularly interesting.

Changes observed in such studies point to the potential of bioactive compounds from medicinal mushrooms in supporting the body’s adaptive response and physiological balance.

In studies using combinations of several medicinal mushrooms, the results cannot be attributed to a single ingredient alone. However, they help improve our understanding of the mechanisms in which Ganoderma lucidum is also being investigated.

Reishi is particularly interesting in this respect because it contains polysaccharides, beta-glucans, triterpenoids and ganoderic acids.

Reishi and Oxidative Stress

One of the important mechanisms that may connect chronic stress with physiological strain on the body is oxidative stress.

Oxidative stress occurs when the balance between the production of reactive oxygen species and the body’s antioxidant defence systems is disrupted.

Ganoderma lucidum polysaccharides and triterpenoids are being studied in relation to the body’s antioxidant mechanisms.

A 2025 systematic review and meta-analysis included 17 randomised controlled trials with a total of 971 participants. Oxidative stress markers were among the outcomes analysed. The pooled data found a statistically significant effect on glutathione peroxidase (GPx), one of the enzymes involved in the body’s antioxidant defence. Results for other analysed oxidative stress markers were less consistent.

This makes Reishi particularly interesting in research on the body’s antioxidant defence and physiological stress.

Why Is Oxidative Stress Important in the Context of Stress?

Psychological stress, lack of sleep, intense physical activity, inflammatory processes and other factors can increase the body’s overall physiological burden.

Oxidative stress, in turn, can affect cellular function and various regulatory mechanisms in the body.

For this reason, the potential effects of Reishi can be considered from a broader perspective:

Reishi bioactive compounds → support for antioxidant defence → regulation of oxidative burden → more favourable conditions for a normal stress response and recovery processes.

This is one of the mechanisms that helps explain why Reishi and stress represent an interesting area for further scientific research.

Reishi, Sleep and Stress Regulation

Sleep and stress are closely interconnected.

Chronic stress can make it more difficult to fall asleep and can affect sleep quality, while insufficient sleep can increase physiological strain on the body.

Normal sleep is therefore one of the body’s most important recovery mechanisms.

Reishi (Ganoderma lucidum) and its bioactive compounds are also being studied in relation to nervous system function, fatigue and mechanisms involved in sleep regulation.

From the perspective of stress physiology, this is particularly interesting because quality sleep and recovery are closely associated with maintaining a normal daily rhythm of the body’s stress response.

Read more in our article:

Reishi (Ganoderma lucidum), Sleep, Stress and Blood Pressure – What Does the Research Show?

Reishi and Inflammatory Regulation

Another important field of research involves inflammatory signalling mechanisms.

The inflammatory response itself is a normal part of the body’s defence system. It helps the body respond to injury, infection and other challenges.

Ganoderma lucidum polysaccharides and triterpenoids are being investigated in experimental studies in relation to several molecular mechanisms, including NF-κB, MAPK and TLR-related signalling pathways.

For this reason, Reishi bioactive compounds are being studied in the context of supporting normal inflammatory responses and immune regulation.

This relationship is particularly interesting because stress, oxidative burden, immune regulation and inflammatory signalling mechanisms interact with one another within the body.

Reishi, Immunity and Stress

Cortisol and the immune system are not two completely independent systems.

Cortisol is involved in regulating immune responses, while signalling molecules produced by the immune system can interact with the body’s stress-regulation systems.

In this context, Reishi beta-glucans are particularly interesting.

In a randomised, double-blind, placebo-controlled clinical trial, healthy adults consumed β-1,3/1,6-D-glucan derived from Ganoderma lucidum for 84 days. Statistically significant differences were observed in several immune parameters, including CD3+, CD4+ and CD8+ T lymphocytes, NK cell numbers, NK cell cytotoxic activity and IgA levels.

This demonstrates that at least some Ganoderma lucidum bioactive compounds have been clinically investigated for their interaction with the human immune system.

Read more in our article:

Reishi and Immunity: How Ganoderma lucidum Interacts With the Immune System and What Research Shows

Reishi, the Gut Microbiome and the Stress Response

Increasing attention is being paid to the interaction between the gut, brain and immune system.

The gut microbiome produces various metabolites and interacts with both the immune system and the nervous system.

Chronic stress, in turn, can influence both intestinal function and the environment of the gut microbiome.

Ganoderma lucidum polysaccharides are being studied in relation to the composition of the gut microbiome and the intestinal barrier, making this another interesting area of Reishi research in the context of overall physiological balance.

Read more in our article:

Reishi After Antibiotics: Gut Microbiome, Immunity and Supporting the Body

Reishi, Oxidative Stress and Blood Vessels

Oxidative stress is also studied in the context of cardiovascular health.

Particular attention is given to lipoprotein oxidation, endothelial function, inflammatory signalling and the body’s antioxidant defence.

Research into the antioxidant mechanisms of Ganoderma lucidum therefore also overlaps with research into cardiovascular physiology.

Read more in our article:

Reishi and Cholesterol: LDL, Blood Vessels and What Scientific Research Shows

How Could Reishi Support the Body’s Stress Response and Normal Cortisol Regulation?

The potential role of Reishi in this context is best viewed as a combination of several interconnected mechanisms.

Antioxidant defence. Ganoderma lucidum is being studied in relation to the body’s antioxidant mechanisms and biomarkers of oxidative stress.

Sleep and recovery. Normal sleep supports the body’s recovery processes and is closely associated with normal stress regulation.

Inflammatory regulation. Reishi polysaccharides and triterpenoids are being studied in relation to molecular mechanisms involved in regulating the body’s inflammatory response.

Immune regulation. The effects of Ganoderma beta-glucans on several parameters of the human immune system have also been investigated in a randomised controlled clinical trial.

Gut microbiome. The interaction of Reishi polysaccharides with the gut environment represents another potentially important area of research into the body’s overall regulatory mechanisms.

Together, these processes provide an interesting biological basis for studying Reishi in the context of supporting the body’s adaptation, physiological balance and normal stress response.

Why Does Reishi Extract Quality Matter?

Not all products sold under the name Reishi are the same.

Mushroom powder, mycelium and a standardised Ganoderma lucidum fruiting body extract can differ considerably in their concentrations of bioactive compounds.

When choosing a Reishi extract, it is worth considering:

• the use of the Ganoderma lucidum fruiting body;
• the extraction method;
• polysaccharide content;
• triterpenoid content;
• ganoderic acid content;
• laboratory composition testing;
• the absence of unnecessary fillers.

Standardisation makes it possible to compare different Reishi extracts according to their concentrations of active compounds rather than simply the total amount of mushroom powder.

ReishiPremium.com – Standardised Ganoderma lucidum Extract

ReishiPremium.com offers a concentrated Ganoderma lucidum fruiting body extract standardised according to the content of its main biologically active compounds.

Reishi Premium contains:

≥30% polysaccharides

≥6% triterpenoids

≥3% ganoderic acids

This standardisation allows the Reishi extract to be evaluated according to the concentration of the principal Ganoderma lucidum bioactive compounds.

Reishi Premium is a standardised Ganoderma lucidum extract providing defined concentrations of polysaccharides, triterpenoids and ganoderic acids.

https://www.reishipremium.com/en/

Reishi and Cortisol – What Does the Overall Picture Show?

When looking at the scientific research as a whole, the most interesting aspect is not one isolated mechanism.

Research into Reishi (Ganoderma lucidum) covers several interconnected areas:

• stress and the body’s adaptation;
• oxidative stress and antioxidant defence;
• sleep and recovery;
• inflammatory regulatory mechanisms;
• immune system function;
• the gut microbiome.

This makes Ganoderma lucidum an interesting source of bioactive compounds in research into the body’s normal stress response and physiological balance.

Summary

Cortisol is an essential part of the body’s stress-regulation system. Therefore, the goal is not simply to achieve lower cortisol levels, but to maintain a normal stress response, circadian rhythm and the body’s ability to recover after periods of increased demand.

Reishi (Ganoderma lucidum) contains polysaccharides, beta-glucans, triterpenoids and ganoderic acids whose biological activity is being investigated in several processes associated with stress and recovery.

Of particular interest is the relationship between Reishi and antioxidant defence mechanisms, oxidative stress, immune regulation, inflammatory signalling, sleep and the gut microbiome.

Together, these mechanisms provide a scientific basis for further research into Ganoderma lucidum in relation to adaptation to stress and support for normal physiological regulation.

Scientific Sources

Chen S.-N., Nan F.-H., Liu M.-W. et al. (2023). Evaluation of Immune Modulation by β-1,3; 1,6 D-Glucan Derived from Ganoderma lucidum in Healthy Adult Volunteers, A Randomized Controlled Trial. Foods, 12(3), 659. DOI: 10.3390/foods12030659.

The Nutritional Significance of Ganoderma lucidum on Human Health: A GRADE-Assessed Systematic Review and Meta-Analysis of Clinical Trials (2025). The systematic review and meta-analysis included 17 randomised controlled trials with a total of 971 participants.

Important information: Reishi (Ganoderma lucidum) is not a medicine and is not intended to diagnose, treat or cure disease. Reishi contains biologically active compounds — polysaccharides, beta-glucans, triterpenoids and ganoderic acids — that are being studied in relation to the body’s antioxidant defence, immune regulation, inflammatory response, sleep, stress and other physiological regulatory processes. Reishi can be considered as complementary support for maintaining normal physiological processes and overall balance, rather than as a medicine or a substitute for medical treatment.

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