Reishi Mushrooms 101: Benefits, Uses, and Side Effects

In the realm of natural remedies and holistic health practices, reishi mushrooms have received a lot of attention in recent years. Used for centuries in Eastern medicine for their potential health benefits, these fungi have found their way into the Western wellness spotlight. As more people seek alternative approaches to health, the interest in reishi mushrooms continues to grow, driven by their potential to support immune function and improve well-being. Keep reading to learn about what science has found about these powerful mushrooms.

What are reishi mushrooms?

Scientifically known as Ganoderma lucidum, reishi mushrooms are a species of fungi cultivated and used in traditional Chinese, Japanese, and other Asian medicines for centuries. Lucidus is the Latin word for 'shiny' or 'brilliant,' which describes their dark, shiny exterior.

These large mushrooms, with their wood-like texture, typically grow on decaying hardwood trees in humid climates in regions of Asia and North America. They come in a multitude of colors including black, blue/green, white, yellow, purple, and the most common color, red. It’s believed that the fruiting body (stalk and cap) is the main part of the mushroom responsible for its potential health benefits. However, the spores and mycelium (root system) have also been investigated.

Reishi mushrooms are often considered medicinal mushrooms as they have been shown to potentially have medicinal properties outside of just being food. Their potential ability to address certain health concerns has earned them this title. Reishi mushrooms can be used in culinary dishes such as soups, stews, and sautés. Additionally, reishi mushrooms have become increasingly available in various supplement forms, including powders, capsules, extracts, and teas.

Do reishi mushrooms work?

Reishi mushrooms contain a handful of active compounds being studied for their therapeutic effects. For instance, polysaccharides and triterpenes (a subclass of terpenes) are compounds believed to give reishi mushrooms their powerful health impacts.

The textbook Herbal Medicine: Biomolecular and Clinical Aspects gives an in-depth analysis of reishi mushrooms, specifically the composition, constituents, and actions of these compounds within the mushroom. They stated that the polysaccharides in reishi mushrooms show a broad range of biological activities including acting as an anti-inflammatory, hypoglycemic, antiulcer, antitumorigenic, and immunostimulant. In addition, the triterpenes have been found to have anti-inflammatory, antitumorigenic, and hypolipidemic activity. The combination of these substances seems to be able to lower inflammation, support the immune system, balance blood sugars, and prevent tumor/cancer formation.

Reishi mushrooms are also high in minerals like potassium, calcium, magnesium, selenium, silica, sulfur, and phosphorus — all of which are necessary for general health and wellness. Current studies introduce the potential of reishi mushrooms to be effective in different health dimensions. However, more clinical studies are needed to support its effectiveness and explain underlying mechanisms.

Potential benefits of reishi mushrooms

The proposed benefits of reishi mushrooms span a wide range of health concerns, making them a versatile option for people seeking natural remedies. Some of the most commonly investigated potential benefits include immune health, anti-cancer and antioxidant properties, blood sugar, and fatigue support.

1. Immune system support

Reishi mushrooms are often touted for their ability to support the immune system, thanks to their rich content of polysaccharides and terpenes, which are believed to enhance the body's defense mechanisms against invaders like bacteria. These compounds also modulate the activity of important immune cells (T cells, B cells, and natural killer cells), increasing the production of glycoproteins that regulate the immune system.

Reishi compounds have also been investigated for their antiviral actions, specifically their ability to inhibit the effects of certain viruses. One study found reishi to exhibit antimicrobial activity in bacteria, like Micrococcus luteus, Proteus vulgaris, Escherichia coli. Although reishi has shown lots of promise to support against bacteria, more recent studies are needed to support these powerful benefits for the immune system.

2. Antioxidant properties

Bioactive compounds present in reishi are known for their antioxidant properties, which may help fight oxidative stress and inflammation, potentially reducing the risk of chronic diseases and supporting overall health. Oxidative stress occurs when free radicals (unstable molecules) damage healthy cells, leading to dysfunction and disease.

The Phytotherapy Research Journal reported that the polysaccharides extracted from reishi mushrooms had antioxidant properties, were able to be absorbed into rat brain tissue cells, and inhibited certain free radicals, with the effect getting stronger as the dose of polysaccharide extract increased.

3. Anti-cancer effects

Numerous studies have proposed that the major components in reishi mushrooms may exhibit chemopreventive and/or tumoricidal effects, proposed to work through inhibitory effects on tumor angiogenesis (new blood vessel formation) and metastasis (the spread of cancer cells in the body from the place where they first formed).

One study tested 58 basidiomycetes mushrooms, of which reishi was shown to be the most effective in killing cancer cells. Other sources describe that reishi may induce cancer cell apoptosis in colon, ovarian, liver, prostate, cervical, lung, breast, and bladder cancers. It was also proposed that reishi has potential against specific types of leukemia and sarcoma cancers.

A clinical study published in the research journal Immunological Investigations included 34 patients with advanced cancers of different types who were given 1,800 mg three times daily of reishi polysaccharide extract supplement capsules for 12 weeks. The supplementation resulted in significant increases in plasma interleukin (IL)-2, IL-6, and interferon γ levels and natural killer (NK) cell activity. What exactly does all this science stuff mean? It means that reishi polysaccharides may play a role in increasing immune response against cancer cells via modulation of inflammatory compound profile and immune cell activity.

These results show us that reishi mushroom intake is possibly promising in regard to cancer treatment and prevention. However, it’s important to note that there is a lack of research in humans, most current studies included small patient samples with large heterogeneity making it difficult to interpret results, so further research is needed to know more about the anti-cancer effects of these mushrooms.

4. Improved heart health

Studies suggest that reishi mushrooms may contribute to cardiovascular health by lowering cholesterol levels, reducing blood pressure, and promoting healthy circulation. However, research is still inconsistent and inconclusive in this regard. More research needs to be conducted to know for sure, but animal studies do look promising.

5. Blood sugar support

One study administered reishi mushrooms to 71 adult patients with type 2 diabetes. The patients were split up into two groups, one being a placebo group and the other given 1,800 mg of reishi orally, three times per day, for 12 weeks. After the 12 weeks, results showed hemoglobin A1c (average blood sugar over 3 months) and blood glucose were significantly lower in the group that was given reishi mushrooms. Even though emerging research holds promise for potential diabetes management in the future, more studies are needed to know exactly how it works.

6. Reduced fatigue

Reishi mushrooms have been investigated for their potential in addressing fatigue. In a research study, 132 patients with neurasthenia (a medical condition characterized by severe fatigue and mood imbalance) were given 1,800 mg of reishi extract three times daily for eight weeks. The results showed that nearly 52% reported improvements in their symptoms compared to the placebo group. Further research on a healthy sample is needed to support these effects.

To conclude, emerging research suggests that the active compounds in reishi mushrooms hold promise in supporting several aspects of health, but more human studies are needed to know for sure.

Potential side effects and considerations

While generally regarded as safe for most people when consumed in appropriate amounts, reishi mushrooms may cause adverse reactions in some individuals. Possible side effects include digestive upset, allergic reactions, and interactions with certain medications. Additionally, people with bleeding disorders or those preparing for surgery should exercise caution when using reishi due to its potential anticoagulant effects.

Some of the most common side effects of taking reishi mushrooms include:

• Dizziness
• Dry mouth
• Nausea and/or stomach upset
• Rash and/or skin itching
• Sleep issues

Who should not take reishi mushroom supplements:

• Individuals who are pregnant or breastfeeding
• People who have bleeding disorders or who are taking anticoagulant or antiplatelet drugs
• Anyone having surgery within the next two weeks
• Those taking blood pressure or cholesterol medications
• People taking immunosuppressants, cancer drugs, or any medications that impact the immune system

The Journal of Integrative Cancer Therapy showed reishi to be generally well tolerated with only minimal side effects like nausea and insomnia in some cancer patients. The journal found no reports of significant hematologic or hepatological toxicity; however, some publications have reported liver problems in rare cases.

Rare liver toxicity concerns

It is important to note that although very rare, liver toxicity reports while taking reishi are possible. One journal reviewed a few cases where people switching from boiled reishi mushrooms (tea) to concentrated reishi powder supplements developed acute hepatotoxicity, with one case being fatal. In the case of fatality, the woman was taking one capsule of 400 mg of reishi per day for two months before having any symptoms. These cases were unique as these people were also taking other medications (and in some cases multiple medications) or consuming alcohol while taking the reishi, which might have had a negative cumulative effect on their liver health.

The British Journal of Nutrition reported that four capsules of 1,440 mg (1.44 g) of reishi powder per day given to volunteers for one month didn't show any hepatotoxic effects or drug accumulation. In general, reishi mushroom studies like this one continue to report high safety in those taking the mushroom. Nonetheless, it is advised to exercise caution and seek the advice of a medical professional to ensure your safety (especially if you are taking other medications or supplements).

How to use reishi mushrooms

There is no established recommended dose for reishi, but in research, doses ranged up to 2,000 mg, depending on the form and concentration of the product taken.

Reishi products can be consumed in various forms, including capsules, powders, extracts, or teas. You can also eat reishi mushrooms in culinary dishes like soups, stews, or sautees. Users should follow the brand's regulations on appropriate dosage and consult healthcare professionals before implementing reishi into their daily routine.

Should you try using reishi mushrooms?

As reishi mushrooms gain popularity, scientists continue to explore their safety and efficacy in humans. Some emerging research suggests they could be beneficial for your health, possibly supporting the immune system and regulating blood sugar. Still, more human studies are needed to ensure efficacy and safety.

While integrating reishi products into one's routine, it’s important to prioritize safety and seek guidance from a qualified healthcare professional to ensure your wellness journey is suitable for your health status.