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Nutritional Benefits of Mushrooms

Mushrooms are extremely high in fiber and contain high levels of the vitamins thiamine, riboflavin, niacin, biotin, ascorbic acid, cobalamins, and the minerals potassium and phosphorus. Recently, medicinal mushrooms have come under close scrutiny as a “wonder drug” of the 21st century. There have been claims that mushrooms enhance the immune system, inhibit the growth of tumors, and help in eliminating the body of cancer and pathogens.

The study of mushrooms and fungi has led to a variety of major pharmaceutical discoveries in the past. For example, the statin series of cholesterol lowering drugs were based upon fungi research in which mushrooms were shown to produce massive quantities of vitamin D when exposed to ultraviolet light. Mushroom research led to the discovery of penicillin, ciclosporin and other drugs, and continues on a global scale.

The History of the Mushroom

Throughout history, various cultures have used medicinal mushrooms. Ancient Egyptians considered the mushroom a special food eaten only by the privileged few in royal families. Asian countries are renowned for their use of medicinal mushrooms, specifically China and Japan. Russians have also used mushrooms. Asian and Eastern European cultures have long held traditions of using herbs and medicinal mushrooms as a way of life.

Many mushrooms are poisonous. It has been suggested that the reason why the Western world decided not to consider the mushroom worthy of research was because the ancient Greeks and Romans had ignored it. This was largely due to the fact that mushrooms were associated with murk, mire and filth, not to mention that some mushrooms are deadly poisonous. Ancient Greeks lacked the knowledge necessary to distinguish poisonous mushrooms from the edible variety. It has not been possible until recently to differentiate certain types of poisonous mushrooms from non-poisonous. Raw poisonous mushrooms can be distilled or cooked, revealing their amazing medicinal properties.

Current Interest in the Medicinal Value of Mushrooms

The interest in the medicinal mushroom began to emerge in the 21st century as a global phenomenon. Lagging behind Asia and Europe, the West has only begun to explore the concept of medicinal mushrooms and their hidden potential. In 2008, UC Davis published a review of medicinal mushrooms encouraging further research through clinical trials. There are currently studies underway at the City of Hope National Medical Center and the Memorial Sloan-Kettering Cancer Center.

Mushroom Health Benefits

While most of the research currently underway suggests that medicinal mushrooms appear to offer anti-cancer and immune system enhancing activity, there is research confirming many health benefits attributed to certain species of mushrooms:

• Mushroom polysaccharides and the immune system. Clinical and animal studies suggest medicinal mushrooms may be able to increase certain aspects of the immune system. Compounds in medicinal mushrooms most responsible for up-regulating the immune response, are a specific type of polysaccharide known as beta-glucans. Lentinan, is a beta-glucan isolated from the shiitake mushroom.
• Research on direct antiviral and antimicrobial properties. Mushrooms must produce and secrete antiviral, antibacterial, and antifungal compounds to survive in the wild against competing or pathogenic organisms. It is believed that certain mushrooms have antiviral properties against polio, hepatitis B, HIV, influenza and other known viruses. Some mushrooms have shown anti-microbial effects on E. coli and Bacillus cereus organisms.
• Tumor inhibition. Preclinical studies suggest that compounds from up to 200 species of mushrooms may inhibit tumor growth, but required dosage and effects on humans is mostly unknown.
• Mushroom antioxidant activity. Mushrooms are known to contain antioxidants such as ascorbic acid, tocopherols, phenolic compounds, and carotenoids. Examples of mushrooms with documented antioxidant activty include maitake, Agrocybe aegerita, reishi, Agaricus blazei, oyster mushrooms, Agaricus bisporus, chaga, and shiitake. Chemical analysis has shown that a specific antioxidant found in some mushrooms like Flammulina velutipes] and Agaricus bisporus is ergothioneine.
• Mushroom effect on blood sugar. Research has shown that some medicinal mushrooms may be able to lower elevated blood sugar levels. Mushrooms noted for this ability to lower blood sugar include reishi,, Agaricus campestris], Agaricus blazei, chaga, Agrocybe aegerita, and Cordyceps. Explanation for this effect on blood sugar is limited, with the exception of the maitake mushroom; its ability to lower blood sugar levels has been explained by the fact that the maitake mushroom naturally contains a compound known as an alpha-glucosidase inhibitor.
• Mushroom effect on cholesterol. Some mushrooms like reishi and Agaricus blazei have been shown to be able to have an inhibitory effect on cholesterol levels. Oyster mushrooms have been found to naturally contain a statin drug known as lovastatin (brand name: Mevacor, Altoprev) a drug used to lower cholesterol. Tests have shown the oyster mushroom contains up to 2.8% lovastatin on a dry weight basis. Animal research has shown that oyster mushroom consumption lowers cholesterol levels. Shiitake mushrooms have been found to contain a specific anticholesterol compound known as eritadenine.
• Direct antihormone activity. Mushrooms may be able to influence the production of certain human hormones, based on evidence from enzyme assay analysis. Mushrooms like Agaricus bisporus may be able to partially inhibit the activity of aromatase, the enzyme responsible for producing estrogen. Some researchers have proposed that this antiaromatase activity may be responsible for studies that have linked an inverse relationship between dietary intake of mushrooms and risk of breast cancer. Mushrooms like reishi may be able to partially inhibit the activity of 5-alpha reductase, the enzyme responsible for producing dihydrotestosterone.
• Vitamin D2. Mushrooms contain large amounts of vitamin D2 when exposed to UV light. Mushrooms are the only crop that is known to naturally contain vitamin D.

Species of Medicinal Mushrooms

Medicinal mushrooms come in a dozen varieties. One of the most popular in China is the Lingzhi, or “spirit plant” as it is known. It has been in use for thousands of years in Asia, and it is depicted as a symbol of health in the residences of the Emperor in the Forbidden City and Summer Palace, and in the hands of their goddess of healing, Kuan Yin. Modern research has revealed that the Lingzhi mushroom has anti-cancer properties, antibacterial, antifungal and antiviral attributes, antioxidant qualities, in addition to liver protecting qualities.

Sometimes used in conjunction with chemotherapy, trametes versicolor is a special type of mushroom that is perhaps the best documented medicinal mushroom in the world. The Japanese Health and Welfare Ministry approved the use of this mushroom in the 1980s for treating stomach cancer and colorectal cancer. MD Anderson, one of the United States’ premier cancer hospitals, has stated that the trametes versicolor mushroom is a “promising candidate for chemoprevention”.

The Memorial Sloan-Kettering Cancer Center recently finished a study that showed the maitake mushroom can stimulate the immune systems of breast cancer patients. The maitake mushroom was approved by the FDA for Investigational New Drug Application status. The agaricus blazei is a mushroom that research has shown to possess the ability to stimulate the immune system; it also exhibits anti-cancer activity and is now being aggressively tested by research labs. The Memorial Sloan-Kettering Cancer Center recently stated, “There is some proof showing the extract may benefit patients with certain cancers, but more studies are needed to confirm these observations.”

Additional medicinal mushrooms include:

• Shiitake mushroom. The shiitake mushroom is one of the most popular culinary mushrooms in the world. During the Ming Dynasty (AD 1368–1644), physician Wu Juei wrote that shiitake was a remedy for upper respiratory diseases, poor blood circulation, liver trouble, exhaustion, and weakness. Modern research has indicated that shiitake mushroom may stimulate the immune system, reduce platelet aggregation, possess antibacterial properties, possess antiviral properties, possibly through anti-viral agents known as proteinase inhibitors. The shiitake mushroom's cancer curing properties are currently being observed by the City of Hope National Medical Center, targeting the inhibition of lung cancer.
• Agaricus bisporus (common mushroom, portobello, champignon mushroom). The white button, crimini, and portobello (common mushroom, champignon mushroom) is the world's most popular edible mushroom, and is known by many names. Researchers at the City of Hope National Medical Center are studying whether this mushroom may inhibit breast cancer development. White button mushrooms may reduce the risk of breast cancer, because they have been shown in vitro to inhibit the enzyme aromatase, which is used by the body to create estrogen. The FDA and the National Cancer Institute have proposed to study U.S. (NHANES) food consumption data to explore whether mushrooms and their vitamin D2 content may reduce the risk of breast cancer. In vivo research conducted on mice suggests the white button mushroom may enhance aspects of the immune system. In vitro testing has shown a compound present in the white button mushroom has anticancer properties, inhibiting the growth of various cancer cell lines. The white button mushroom is also a rare vegetable source of conjugated linoleic acid (CLA).
• Agrocybe aegerita. Agrocybe aegerita (chestnut mushroom, velvet pioppino, Agrocybe cylindracea, yanagimatsutake, zhuzhuang-tiantougu) contains compounds with inhibitory properties against the enzyme cyclooxygenase (the same enzyme which is the target of Advil, Tylenol, and other NSAIDS).An in vitro experiment, revealed the mushroom may offer anti-cancer and immune-stimulating properties.
• Cordyceps mushroom. The cordyceps mushroom has a long history in traditional Chinese medicine as well as traditional Tibetan medicine.Research has indicated Cordyceps mushroom may promote cellular health, have anti-depressant activity, as well as possible anti-cancer activity.
• Flammulina velutipes (Enokitake). Enokitake (えのき茸, 팽이버섯) are long, thin white mushrooms commonly used in Asian cuisines. Enokitake mushrooms contain compounds with antitumor activity, and epidemiological studies in Japan have associated the mushroom with lower cancer rates. In vivo research showed that proflamin, a compound isolated from enokitake provided an 85% longer survival time in mice with cancer. Another in vivo study showed that enokitake demonstrated anticancer activity in Swiss albino mice with Sarcoma 180.
• Fomes fomentarius (Tinder conk mushroom, Tsuriganetabe). the formes fomentarius mushroom contains compounds with anticancer activity.
• Hericium erinaceus. Hericium erinaceus (lion's mane mushroom, yamabushitake, 山伏茸, 猴头菇) has been researched for possible antidementia activity. In vitro experiments with Hericium have demonstrated its ability tostimulate nerve growth factor in human astrocytoma cells, stimulate rat nerve cells,and stimulate myelination. Additionally, a double-blind, parallel-group, placebo-controlled trial showed that supplementation with Hericium improved cognitive ability.
• Inonotus obliquus (Chaga mushroom). The chaga mushroom (kabanoanatake) has anticancer properties and may be able to stimulate the immune system. In one experiment, mice implanted with B16F10-melanoma, showed a 4.07-fold increase in survival rate when given a compound isolated from the chaga mushroom. The Chaga mushroom contains betulin and inotodiol, two compounds which have demonstrated ability to induce apoptosis of certain cancer cell lines (mouse leukemia P388 cells, Jurkat cells). Researchers have noted the Chaga mushroom has anti-inflammatory properties.[221][222] For centuries, Chaga mushrooms have been used in parts of Russia, Poland, and Belarus for medicinal purposes. In Russia an extract of Chaga, known as befungin, is considered an approved medicine.
• Lentinula edodes isolate. Lentinan, a compound isolated from shiitake, is used as an intravenous anticancer agent in some countries. Studies have demonstrated lentinan possesses antitumor properties, and human clinical studies have associated lentinan with a higher survival rate, higher quality of life, and lower reccurrence of cancer. Clinical research with lentinan includes studies with 78 hepatocellular carcinoma patients, 32 gastric cancer patients,] a multi-institutional study of lentinan and gastric cancer, a meta-analysis of lentinan and gastric cancer, 80 colorectal cancer patients, 20 gastric cancer patients, 36 hepatocellular carcinoma patients, and 29 pancreatic cancer patients. The City of Hope National Medical Center is currently conducting clinical trials to determine if a select portion of the shiitake mushroom, which includes lentinan, can inhibit lung cancer.
• Phellinus linteus mushroom. Extracts from Phellinus linteus (mesima, meshimakobu, song-gen, sang-hwang) have been used for centuries in traditional Korean medicine. A paper published by Harvard Medical School, reported that Phellinus linteus mushroom is a promising anticancer agent. However, the paper states more research is needed to understand the mechanisms behind Phellinus linteus. In vitro research published by the British Journal of Cancer, demonstrated one anticancer mechanism behind Phellinus linteus. It was found that the mushroom inhibited the growth of breast cancer cells by way of inhibiting the enzyme AKT, as well as inhibiting angiogenesis.
• Piptoporus betulinus. Piptoporus betulinus (birch bracket mushroom, kanbatake) may possess anticancer properties, anti-inflammatory properties, anti-bacterial properties, and anti-viral properties.
• Pleurotus eryngii  (King oyster mushroom). Pleurotus eryngii (king oyster mushroom, 杏鮑菇, エリンギ) is an edible mushroom. In vitro research with murine T-cells, showed king oyster mushrooms may stimulate the immune system by way of increasing production of interferon-gamma and IL-4.
• Sparassis crispa. Sparassis crispa (cauliflower mushroom, hanabiratake) has been found, in vivo, to contain compounds which stimulate the immune system and offer an anticancer effect. In vivo research showed a compound contained in the mushroom inhibited solid Sarcoma 180 tumors in mice. An in vivo experiment with leukopenic mice, noted that a beta-glucan isolated from the mushroom stimulated white blood cell production. One in vitro experiment with human blood cells noted an extract of the mushroom could stimulate IL-8 production.