The Magic of Mushrooms! Current Evidence

If you are not consuming mushrooms on a regular basis, you may be missing out on some pretty amazing health benefits! Aside from tasting great in soups, pastas, and numerous dishes, mushrooms boast impressive health and immune boosting properties. Read on to learn about the latest research findings concerning mushrooms and health!

Disclaimer: the information contained in this article is not a substitute for medical advice. Decisions concerning treatment and prevention of various health conditions need to be coordinated with your medical provider. Additionally, much of the following research is promising, but limited to small human trials and animal studies. More research is needed to confirm the clinical effects described below in humans.

Mushrooms and health: nutritional properties

Mushrooms have been consumed for all of recorded history (Valverde, Hernández-Pérez, & Paredes-López, 2015). The Greeks believed mushrooms gave warriors strength, and various cultures called mushrooms by titles such as “elixer of life,” and “Food of the Gods” (Valverde et al., 2015). Mushrooms contain a variety of nutritional properties depending on species such as:

• Selenium
• Magnesium
• Calcium
• Copper
• Iron
• Zinc
• Potassium
• Riboflavin
• Niacin
• Vitamin D ( the only non-animal food source of vitamin D–contained in varying amounts by species and growing methods)
• Vitamin C
• Proteins
• Fiber (Valverde et al., 2015)

Mushrooms are cholesterol-free, low calorie, low fat, low carbohydrate foods. Of more than 2,000 species, only 25 species are consumed widely. Aside from basic nutritional properties, mushrooms are being researched for their unique health-promoting and potential disease fighting properties (Valverde et al., 2015).

Mushrooms and researched healing properties

Mushrooms and yeasts are rich in compounds such as lectin, β-glucan, ergosterol, arginine, and additional bioactive compounds (Novaes, Valadares, Reis, Gonçalves, & Menezes, 2011). Research has found the following effects of these compounds:

• Lectins: anti-cancer activity due to toxic effects on cancer cells, promotion of cancer cell self-destruction (apoptosis), prevention of tumor growth due to preferential binding to cancer cell membranes, and prevention of blood vessel growth (angiogenesis) in tumors
• β-glucans: stimulates immune system activity against cancer cells by promoting activity of natural killer cells, neutrophils, T-cells, macrophages, and monocytes.
• Ergosterol: also known as provitamin D2, ergosterol inhibits angiogenesis in tumors leading to slowed growth rates, as well as demonstrates anti-proliferative, anti-migratory/ anti-metastasis, and anti-tumor effects
• Arginine: an amino-acid considered semi-essential, arginine has been used in cancer patients to prolong survival, improve appetite, slow metastasis and slow tumor growth
• Bioactive compounds: numerous bioactive compounds including phenolic compounds vary depending on mushroom species, with compounds demonstrating anti-viral, anti-thrombotic, antibiotic, anti-inflammatory, anti-allergenic, anti-fungal, anti-diabetic, anti-oxidant, and neuro-protective effects (Hetland, Johnson, Lyberg, Bernardshaw, Tryggestad, & Grinde, 2008; Li et al., 2018; Martin, 2010; Novaes et al., 2011; Valverde et al., 2015)

Interestingly, humans have cell receptors designed to recognize and react to mushroom and yeast β-glucans (Firenzuoli, Gori, & Lombardo, 2008)! These receptors are widely expressed in a variety of human tissues. Also interesting, the same human cell receptors that recognize and respond to β-glucans can also recognize and respond to various human immune T-cells (Firenzuoli et al., 2008).

The clinical significance of this discovery is the subject of ongoing research. The types and amounts of the above health promoting compounds vary by mushroom species. As such, different mushrooms are being researched and utilized for different health purposes (Seo, Patel, Shin, Sim,Lee, & Lim, 2019 ). Consuming a variety of mushrooms as part of a healthy diet may be a way to take advantage of the numerous benefits offered by mushrooms.

Common mushrooms and cardiovascular disease risk reduction?

Research has demonstrated that commonly consumed mushrooms, including crimini, oyster, maitake, and white button mushrooms, may promote cardiovascular health by preventing atherosclerosis (Martin, 2010). Human aortic endothelial cells exposed to extracts of these mushrooms had significant decreases in expression of the adhesion molecules VCAM-1, ICAM-1, and E-selectin. These molecules play a role in promoting atherosclerosis (narrowed arteries) and arterial plaque formation (Martin, 2010).

Additionally, there was decreased binding of human monocytes to the blood vessel tissue (Martin, 2010). The researcher concluded:

The health implications are that diverse mushrooms, including common and specialty mushrooms can protect against cardiovascular disease by interfering with events that
contribute to atherogenesis.”

(Martin, 2010, p 6, para 2)

While this study was completed in a lab setting using human cell cultures, separate animal studies have observed significant reductions in arterial plaques and cholesterol levels when animals were fed with shiitake, oyster, maitake, and white button mushrooms (Martin, 2010). These study results demonstrate potential cardiac benefits of common dietary mushrooms, and there is little risk or downside of consuming these mushrooms. However, human clinical trials are needed to further validate these findings.

Agaricus blazei Murill mushrooms and cancer

Native to Brazil, the Agaricus blazei Murill mushroom has been used traditionally for cancer, hepatitis, diabetes, arteriosclerosis (hardening of the arteries), and for treatment of high cholesterol (Hetland et al., 2008). Research findings note the proteoglucans and β-glucans of Agaricus blazei mushroom species stimulate natural killer cells, polymorphonuclear leukocytes, and produce the following immune responses from macrophages:

• Release of nitric oxide (necessary for induction of inflammatory response)
• Release of TNF-a (induces cell death, protects against infection and cancer, is a pro-inflammatory protein)
• Release of IL-8 (attracts additional immune cells, specifically neutrophils and T cells)
• Release of IL-12 (stimulates natural killer cell production and antiviral interferon production) (Hetland et al., 2008, Luiking, Engelen, & Deutz, 2010; Zhang & An, 2007)

Research into the effects of Agaricus blazei Murill mushrooms on cancer have demonstrated the following effects:

• Regression of tumors in mice
• Reduction in spontaneous metastasis in mice with ovarian and lung cancer cells
• Toll-like receptor binding (stimulates innate immune response and is associated with prolonged survival in cases of relapse)
• Inhibition of fibrosarcoma (connective tissue cancer) in mice
• Induction of apoptosis (cell death) in leukemia cell lines
• Inhibited abnormal collagen fiber formation in human liver cancer cells (abnormal collagen formation is a hallmark of cancer progression)
• Myeloma tumour suppression in mice
• Reduction of side effects during concurrent treatment of gynecologic cancers in humans along with significant increased natural killer cell activity and increased quality of life
• Increased natural killer cell penetration into tumors
• Increases in IFN-α (an immune cytokine that stimulates activity of natural killer cells, macrophages, and has anti-viral effects)
• Inhibition of prostate cancer cell proliferation
• Increased activity in specific genes responsible for cell signalling, cycling, and transcriptional regulation consistent with protection from cancer (Firenzuoli et al., 2008; Hetland et al., 2008; Kawasaki & Kawai, 2014; Valverde et al., 2015; Zhang & An, 2007)

Agaricus blazei Murill mushrooms have immune stimulating properties in humans and mice. In studies on mice, these properties led to improvements in cancer outcomes and survival (Hetland et al., 2008). However, more research is required in humans before making similar conclusions. The mushrooms are commonly consumed as teas, food, or extracts.

Safety concerns may include presence of aromatic hydrazines, a known carcinogen in animals and probable carcinogen for humans (Firenzuoli et al., 2008). Additionally, drug interactions are unknown. Toxicity studies based on 16 weeks of consumption of Agaricus blazei Murill mushrooms demonstrated no clinical problems in the blood examination, urinalysis, physical examination and history taking for human participants.

However, there were three reported cases of liver dysfunction in cancer patients supplementing with Agaricus blazei Murill mushrooms. Other research suggests the mushroom may protect the liver (Valverde et al., 2015). Use may be best coordinated with a healthcare provider.

Shiitake mushrooms and a unique compound

Shiitake mushrooms are rich in a unique compound called lentinan. Combined with the β-glucans found in shiitake mushrooms, these compounds have demonstrated anti-tumor activity, antioxidant activity, as well as cholesterol-lowering properties (Valverde et al., 2015). Fascinating properties of lentinan found exclusively in shiitake mushrooms includes:

• Improved host resistance and direct action against infections by bacteria, fungi, parasites, and viruses
• Activation of the innate nonspecific inflammatory responses
• Blood vessel relaxation/ dilation
• Stimulation of the immune cells helper T cells and cytotoxic T cells
• Use as a supportive / complementary therapy in treatment of cancer (Valverde et al., 2015)

Shiitake mushrooms are safe for consumption but have caused skin reactions and allergic reactions in some people (Memorial Sloan Kettering Cancer Center, 2020).

Maitake mushrooms and health benefits

Used widely in culinary dishes in China, Korea, and Japan, maitake mushrooms (Grifola frondosa) are rich in unique β-glucans (Seo et al., 2019). β-glucans have differing impacts on the immune system based on their particle size and structures. The β-glucans, α-glucans and other compounds found specifically in maitake mushrooms have been found to stimulate production of the following immune cytokines:

• Interleukin-1, interleukin-6, tumor necrosis factor α (pro-inflammatory cytokines)
• interleukin-12 (stimulates natural killer cell production and antiviral interferon production)
• T helper-1 cytokine interferon-γ (stimulates activation of natural killer cells, macrophages, neutraphils, stimulates cell-mediated immunity, and promotes antiviral effects)
• T helper-2 cytokines interleukin-4 and interleukin-10 (anti-tumor activity) (Seo et al., 2019; Zhang & An, 2007)

As noted above, the immune system cytokines stimulated by maitake mushrooms have anti-viral, anti-cancer, and anti-bacterial effects. Maitake mushrooms are considered safe for consumption and non-toxic (Memorial Sloan Kettering Cancer Center, 2020).

Lion’s mane mushrooms and health benefits: nerve health

The lion’s mane (Hericium erinaceus) mushroom has demonstrated the ability to stimulate nerve growth factor in the central nervous system of rats (Li, Lee, Tzeng, Chen, Chen, Shiao, & Chen, 2018). An active compound found in the lion’s mane mushrooms believed to be responsible for stimulating nerve growth factor is erinacine A (Li et al., 2018). Researchers note for sufferers of ischemic stroke, Parkinson’s, Alzheimer’s, and depression, daily inclusion of lion’s mane mushrooms in the diet led to improvements in symptoms in preclinical trials (Li et al., 2018).

Numerous compounds from the lion’s mane mushroom have shown neurotrophic activities (Li et al., 2018). A small double-blinded placebo controlled trial compared two groups of 15 patients ages 50-80 with mild cognitive impairment (Mori, Inatomi, Ouchi, Azumi, & Tuchida, 2009). One group received four 250 mg tablets containing 96% lion’s mane mushroom powder three times per day for 16 weeks. The other group received a placebo.

At the end of the trial, the group taking the lion’s mane powder showed significant cognitive improvements on the Revised Hasegawa Dementia Scale versus the placebo group (Mori et al., 2009). Additionally, when the participants STOPPED taking the lion’s mane powder for four weeks, their improvements declined substantially (Mori et al., 2009). No adverse effects were noted during the trial. Such findings strongly suggest bioactive components of lion’s mane contributed to the observed improvements.

Animal studies demonstrate neuro-protective and healing properties of various compounds found in lion’s mane mushrooms. These effects include the following:

• Prevention of hearing loss versus a control group in mice
• Reduction of damaged tissue by 22%-44% when ischemic stroke was induced in rats versus a control group. Also, reductions were noted in pro-inflammatory cytokines and free radical levels following the stroke in the rats when they were pre-treated with compounds from lion’s mane mushrooms
• Nerve protection in the stratum and substantia nigra against a toxin used to induce Parkinson’s symptoms in animal models when compounds from lion’s mane were taken for the 25 days prior to injection of the toxin. Erinacine A was found to restore motor function despite damage from the toxin.
• Restoration of behavioral functions and lower amyloid-β plaque burdens in mice genetically engineered to develop Alzheimer’s disease. Improvements were noted in various brain regions after ingestion of erincine-A-enriched lion’s mane compounds for a period of 81 days
• Protection against stress induced depression symptoms with reversal of the hormonal and immunological changes that normally occur after severe and intense stress. Low levels of norepinephrine, dopamine, serotonin, and high levels interleukin-6, as well as tumor necrosis factor-α were all reversed in mice subjected to restraint stress with administration of lion’s mane compounds. Release of brain-derived neurotrophic factor, a compound necessary for nerve survival, learning, and growth, was stimulated (Bathina & Das, 2015; Li et al., 2018)

Findings in animal research studies do not always carry over to humans. In the animal studies above, the lion’s mane compounds were concentrated through a fermentation processes to boost the levels of erinacine compounds (Li et al., 2018). Researchers note that lion’s mane mushrooms have low toxicity when consumed at reasonable amounts (such as when part of a healthy diet) and are safe for dietary consumption.

“The mushroom of immortality:” Reishi (Ganoderma)

Reishi mushrooms, also known as lingzhi mushrooms in China, have been used in traditional Chinese medicine for thousands of years (Valverde et al., 2015). Referred to as the “mushroom of immortality,” reishi is valued in Japan, China, and Korea more for its medicinal effects as opposed to culinary applications (Wachtel-Galor et al., 2011). It is consumed in teas, powders, and supplements. Prior to cultivation, wild collection of the mushroom could only be afforded by nobility. Its scarcity led to exaggerated myth-like properties (Wachtel-Galor et al., 2011).

Current research focuses on the unique bioactive compounds which include specific polysaccharides, peptidoglycans, and triterpenes (Valverde et al., 2015). These compounds have been noted to have synergistic anti-inflammatory, blood sugar lowering, anti-ulcer, anti-tumor, antioxidant, anti-parasitic, anti-allergic, and immune stimulating effects (Valverde et al., 2015; Wachtel-Galor et al., 2011). Anti-cancer effects of reishi mushrooms include:

• Direct cytotoxic effects with cancer cells
• Neutralization of carcinogens
• Decreased viability / survival ability of human cancer cells
• Inhibition of cancer cell proliferation and metastasis ability for breast and prostate cancer cells
• Inhibition of tumor invasion, inhibition of tumor metastasis and cell adhesion, and suppression of cell migration in colon cancer cells
• Cancer cell inhibition and destruction in lab settings and animal studies: induction of cell-cycle arrest and apoptosis in various human and rodent tumor cells for over 20 types of cancer!!
• Significant reduction in numbers of cancer cells and tumor size, plus improvements in survival times for mice with a variety of cancers when injected with/ when consuming reishi mushrooms/ extracts
• In human randomized-controlled trials involving 134 patients with advanced cancer of various sites, extracts of reishi mushrooms boosted innate immune activity–resulting in elevated plasma IL-2, IL-6, and IFN-γ levels, and increased natural killer cell activity. A separate study study involving 68 lung cancer patients saw improvements in numbers of T-cells, natural killer cells, and CD4/CD8 ratios (a marker of immune system health) (Valverde et al., 2015; Wachtel-Galor et al., 2011).

Reishi mushrooms are used as a supplementary treatment for diabetes, leukemia, and other cancers, as well as hepatitis (Valverde et al., 2015). Reishi mushroom extracts also appear to have antiviral activity against herpes viruses, the hepatitis b virus, and even the HIV virus. Extracts proved superior to antibiotics in lab (petri-dish) studies against E. coli, Micrococcus luteus, S. aureus, B. cereus, Proteus vulgaris, and Salmonella typhi (Wachtel-Galor et al., 2011).

Like many of the mushrooms already described above, research concerning reishi mushrooms is interesting, and even promising. However, the research is largely based on animal and lab settings, limiting the strength of the evidence in application to humans. What works in a lab or in a mouse does not always work as anticipated in a human. Larger, better designed studies are required featuring clinical trials with human participants.

While reishi mushrooms are generally recognized as safe (Valverde et al., 2015), there are two reported cases of liver toxicity attributed to reishi mushroom powder. One of those two cases resulted in death (Memorial Sloan Kettering Cancer Center, 2020). There are reports of long term use without safety concerns as well, however (Valverde et al., 2015).

Additional mushrooms and health findings

• Antioxidant activity: Chaga mushroom extract protected human lymphocytes from oxidative damage in a lab setting, reducing DNA damage by 40% versus controls when exposed to a strong pro-oxidant (Park, Lee, Jeon, Jung, & Kang, 2004; Valverde et al., 2015)
• The common white button mushroom contains a unique lectin found to be a potent immune stimulant
• L. polychrous, a mushroom native to Thailand, has been found to have anti-estrogen and inhibitory effects on breast cancer
• Oyster mushrooms species have demonstrated antiviral, antitumor, antibacterial, cholesterol lowering, immune system modifying, anti-inflammatory, and antioxidant properties

Risks

In spite of the numerous health promoting properties, there are some risks associated with food grade mushrooms. The substrate in which they are grown is incredibly important, as mushrooms are highly effective at absorbing heavy metals (Bordean, Raba, Alda, Pintilie, Borozan, Harmanescu, & Pirvulesco, 2016). For example, oyster mushrooms ( Pleurotus ostreatus) have been found to extract nickel from their substrate, accumulating levels 2-4 times higher than the recommended intake limit depending on the growing environment (Bordean et al., 2016).

The Pleurotus species of mushrooms also quickly absorb mercury and other toxins, at higher levels than the common button mushroom (Agaricus) species (Bordean et al., 2016). Numerous mushroom species are noted for their ability to absorb and breakdown pesticides and pollutants. They have even been used for restoration of contaminated sites. Due to the potential for contamination, mushrooms need to be procured from reputable sources. Further, they should be consumed as a routine but not excessive part of a balanced, healthy diet.

Summary and tips for use

Mushrooms appear to have a number of shared as well as unique health promoting properties across the various species deemed safe for human consumption. However, caution must be advised in interpreting the research, as many of the studies consist of animal models and lab settings as opposed to large, randomized clinical studies involving human subjects. For me, it makes sense to stick to the mushrooms that have wide dietary usage and well-known safety profiles until more research is available (such as shiitake, maitake, lion’s mane, white button, and oyster mushrooms).

I try to consume mushrooms as part of a balanced diet as whole foods mixed in with various dishes whenever possible. Mushroom varieties can at times seem difficult or expensive to obtain. The easiest and most affordable way I have found to consistently add a variety of mushrooms to my diet has been through the use of dried mushrooms.

While dried and reconstituted mushrooms may not taste the best in stir-fries, they can be readily added to bean/ lentil soups or pastas. The purchase of one pound of dry mushrooms equates to nearly eight times that amount when reconstituted with water!! Dried mushrooms can be purchased by type or in mixed varieties. You may want to try purchasing a small amount of dried mushrooms at first, as some people strongly prefer only fresh mushrooms when cooking due to texture. However, for affordability and ease of use, in my view dried mushrooms are tough to beat!

Thanks for reading! Hope you enjoyed this blog post! Feel free to share with a friend, and remember to sign up for my e-mail list, and most of all, live well!!!!

P. S. – If you liked this post, check out my article “Thank God For Garlic! Health Benefits Of Garlic & Current Research!”

References

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