The Health Benefits of Mushrooms

They seem to come out of nowhere. In areas where there was no visible sign of their presence, they suddenly appear - overnight, or so it seems. Such is the nature of mushrooms, the higher order organisms of the world of fungi. Everyone has had some encounter with mushrooms. Whether on a walk through the woods, strolling through the park, or just finding them in our lawns and gardens, mushrooms are a phenomenon of nature that is hard to overlook.

Unbeknownst to North Americans, except for a handful of researchers and herbalists, certain mushrooms have been employed as herbal medicines for thousands of years in Japan and China. These mushrooms were some of the most effective, yet benign, of the many plants that formed the Oriental herbal tradition. One mushroom, reishi, was so highly revered that whole mythologies were built around it and representations of reishi can be found throughout Oriental art. 

So why haven't we heard more about these mushrooms? For the most part they were rare and therefore expensive. In the case of reishi and maitake, only in the past 20 years has successful cultivation made them more widely available. Other mushrooms such as Coriolus and shiitake have been enhanced by modern fermentation processes which have been developed and refined only recently.

To fully understand mushrooms and mushroom products, a basic understanding of their life cycle is helpful. Most mushrooms are composed of a cap and a stem. The underside of the cap has many thin blades radiating out from the central stem. These blades are called gills and are the spore-bearing surface of the mushroom. Spores are the "seeds" by which mushrooms can spread to new areas. The stem lifts the cap above its environment and enables the spores to be carried away by the wind. The shiitake is an example of this classical mushroom shape.

The use of mushrooms as food has been an enigma in North America. Classically trained nutritionists have stated that mushrooms are of little food value and have based their assessment on the fact that mushrooms are low in calories. It is unfortunate that this misrepresentation has persisted although it is due in large part to an early lack of concrete nutritional information and a general cultural bias. Studies done in the last twenty years clearly show that mushrooms are a nutritionally sound food that are of even greater value to vegetarians.

The most comprehensive study to date was undertaken by Crisan and Sands in "The Biology and Cultivation of Edible Mushrooms" (ed. Chang and Hayes, Academic Press, 1978.) This study gives complete nutritional analyses of over 50 species of wild and cultivated mushrooms. They find that on average, dried mushrooms contain 10% water, all of the essential amino acids, 2-8% fat, mostly in the form of linoleic acid (the only essential fatty acid required in the human diet) 3-28% carbohydrates, 3-32% fiber and approximately 10% minerals. They consider mushrooms to be "good sources of several vitamins including thiamine, riboflavin, niacin and biotin." Pro-vitamin D is present in some mushrooms, particularly shiitake, and is converted to vitamin D by ultraviolet irradiation, including sunlight. They conclude that "the Essential Amino Acid Scores of the most nutritive mushrooms rank in potential nutritive value with those calculated for meat and milk. They are significantly higher than those for most legumes and vegetables. The least nutritive mushrooms, on the other hand, rank considerably lower but are comparable to some common vegetables." They note that there is a great compositional variation between mushroom species and strains(varieties of the same species), a fact born out by the analytical tables they present.

Another important study, "The Nutritional Value of Mushrooms", by Professor Edward Trione of Oregon State University (ed.Tony Walters, Mushrooms and Man, Linn-Benton Comm. College, 1978) looks more closely at the actual bio-availability or digestibility of mushrooms. He recognizes that some of the protein and much of the carbohydrates are bound up in the mushroom cell wall. These cell walls "contain many large carbohydrate polymers such as glucans, chitin, chitosans and mannans, but these polymers are linked together with covalent bonds that cannot be attacked by our digestive enzymes. Therefore, we suspect that a large percentage of the carbohydrate in mushrooms cannot be utilized as nutrients by humans and function only as roughage." Dr. Trione also states that spores are quite nutritious, yet because of the thick tough spore wall, spores "would not yield many of their nutrients...." He concludes that thorough chewing and cooking will break down many cell walls, but not all.

Andrew Weil, M.D., in the Nutrition News section of American Health Magazine, May, 1987, states that drying as well as cooking breaks down mushroom cell walls. An avid proponent of mushrooms, Dr. Weil recommends cooked mushrooms and rice as a way to obtain a balanced and complete protein due to the fact that mushrooms contain the essential amino acids lacking in cereal grains. He also advises against eating raw mushrooms in quantity.

It is fair to say that mushrooms, in a cooked or processed form, represent a valuable food source. But mushrooms have been used in Asia for thousands of years in a much different way; as herbal medicines. It may be that mushrooms were one of the first "nutraceuticals", foods that also function as medicines. In the book, Icones of Medicinal Fungi from China, (Ying, et al., Science Press, Beijing, 1987), the authors document 272 species with reported medicinal properties. Over sixty of these contain polysaccharides which inhibit the growth of specific tumors. Some species can be traced to the earliest records of Chinese Materia Medica, the "Shen Nong's herbal", 1st century B.C. By the time of Li Shih-chen's monumental work, the "Compendium of Materia Medica", A.D. 1600, Li lists over twenty species with medicinal benefits.

Despite the relatively large number of mushrooms identified as having medicinal properties, only a dozen or so species have been seriously utilized or studied. These include: Ganoderma species (reishi or Ling-zhi), Lentinus edodes (shiitake), Polyporus umbellatus, Grifola frondosa (maitake), Coriolus versicolor, Poria cocos, Cordyceps species, Auricularia auricula, Hericium erinaceus, Schizophyllum commune, Flammulina velutipes, and Pleurotus species. The practical research on these mushrooms has gone beyond traditional Chinese medical use and extends to the production and isolation of specific compounds designed for specific illnesses. This development is in tune with the Chinese integration of traditional medicine with Western medicine.

The common bond that is shared by these mushrooms is the occurrence of complex carbohydrates called polysaccharides. Of these, glucans and mannans have been been the primary focus of research due to their ability to inhibit tumors in laboratory test animals. Researchers have found that the structural linkages of these substances is the primary determinant of biological activity and that the active links are most often beta(1-3) and beta(1-6). Furthermore, the activity of these polysaccharides has been shown to be immuno-stimulating rather than directly cell killing. In fact, according to P.K. Tsung, in "Anti-Cancer and Immuno-stimulating Polysaccharides", (OHAI Bulletin, 1987) "Studies of Biologically or immunologically active polysaccharides can be said to constitute the history of the search for anti-cancer agents from an immuno-therapeutical viewpoint." Traditionally, medical practitioners in China and Japan have used the following herbs as anti-cancer medications: ginseng, astragalus, brasenia, laminaria, as well as many of the mushrooms named above. All share a high polysaccharide content.

The specific effect of these polysaccharides is the activation of macrophages and T-lymphocytes, stimulation of interferon, and an enhancement of cell-mediated immune response. Dr. Tsung believes the anti-cancer and immuno-stimulating effects of polysaccharides should be considered as an anti-aging property since our immunity decreases with age. He also views these herbs as health foods that function as preventive medicines. Writing in the same issue of the OHAI Bulletin, H. Yamada states his belief that polysaccharides play the role of regulating homeostasis and immuno-modulation in the human body. Of importance to this use is the fact that immuno-stimulating polysaccharides have no toxic effect on humans and are clinically safe. Given that most of these mushrooms are also used as food strengthens this safety observation.

According to Traditional Chinese medical theory, herbs such as these mushrooms are classified as "superior", are used as tonics, and fit into a category called Fu-Zheng. A modern day corollary would be immuno-therapy. It should be understood that immune enhancement goes beyond help for serious diseases like cancer, AIDS, or Chronic Fatigue Syndrome. It goes to the roots of health itself. The primary function of Fu-Zheng herbs is to increase disease resistance and normalize bodily functions. They are what Steven Fulder calls "harmony" herbs. These mushrooms should therefore be seen as a cornerstone for preventive medicine and a means to maintain a high level of overall resistance to disease in general.

Using the wisdom of Traditional Chinese Medicine as a guide, other health benefits from mushrooms have been elucidated and studied by researchers. These benefits on a mushroom by mushroom basis are as follows:

Lentinus edodes - shiitake
The second most widely cultivated mushroom in the world, shiitake is a culinary delight and a mainstay in the Japanese diet. Because of its use in folk medicine and its availability, it has been the subject of intense research. Cochran¹s review of medicinal mushrooms, "Medical Effects"(Biology and Cultivation of Edible Mushrooms, Academic Press, 1978), lists shiitake extracts as having antifungal, antitumor, and anti-viral effects. The anti-viral effects are believed due to shiitake¹s ability to induce interferon, although because of its oral effectiveness other factors are also suspected. Researchers have reported that oral administration of mushroom powder lowered blood cholesterol levels by as much as 45%. The most dramatic results occurred when high cholesterol foods were eaten at the same time. In two human studies, cholesterol dropped 6-15% when the amount of shiitake consumed was 9 grams per day, or approximately 10 dried medium sized mushrooms. shiitake has also shown the ability to lower high blood pressure in laboratory animals.	The most significant shiitake product on the market today is LEM, an extract produced from mycelia that shows high oral activity. LEM is a trade name for a water extract produced from mycelia grown on a solid media of sugar cane bagasse. The degradation of this bagasse by shiiitake mycelia produces a lignin compound, EP3, that is anti-viral and immunoactive. Lentinan, which is the name given a highly purified polysaccharide fraction of extracted mushrooms, is an approved drug in Japan. It is generally administered by injection and has been used as an agent to prolong survival of patients in conventional cancer therapy as well as in AIDS research. Lentinan is currently in Phase II clinical trials in the U.S.
	Lentinus edodes Shiitake Mushrooms

Ganoderma lucidum - reishi
Reishi, or Ling zhi, is a legendary mushroom that is endlessly depicted in Chinese art and is the subject of many folktales. It has also been given many names, such as "auspicious herb," "miraculous chi," and "holy mushroom", and is looked upon in China even today as a symbol of good fortune. It is recorded as early as 300 B.C. as a "healthy food". Li Shih-chen lists its traditional uses in this way: "Its sensation of taste is bitter, not adverse and never toxic. The prescription benefits symptoms of a knotted and tight chest. It affects in a positive fashion the heart Qi, and mends the chest. It also increases intellectual capacity and banishes forgetfulness. Eaten over a long period of time, agility of the body will not cease and the years are lengthened to those of the Immortal Fairies." Along with shiitake, reishi is the most studied of the medicinal mushrooms. It is unique among these mushrooms in that it not only contains active antitumor polysaccharides, but also a high content of terpenoids.	Steven Fulder, in The Tao of Medicine (Destiny books, 1987), suggests that terpenoids increase our resistance to stress, or "restore harmony", which is a basic definition of "adaptogen". He states, "it is more than coincidence that the active principles of most of the harmony remedies are triterpenoids."  Dan Mowrey, in his book, Next Generation Herbal Medicine (Cormorant Press, 1988), notes that centella, another longevity herb, contains triterpenoids. Research with reishi triterpenes indicates that they play a role in lowering blood pressure, lowering cholesterol, and improving liver function. Other traditional benefits of reishi that have been confirmed by modern scientific research are: calming of central nervous system over-excitation, relief from insomnia, inhibition of allergic reactions, and relief from chronic bronchitis.
	Ganoderma lucidum Reishi Mushrooms

Plant Form
One important aspect of all herbs, and mushrooms are no different, is what plant form to consume and how much? Despite a shortage of Western scientific "clinical trials", there are three basic areas from which this information can be determined. These areas are traditional uses, (which can encompass current as well as ancient use by traditional doctors), scientific research data, and modern uses by holistic medical practitioners. A survey of these spheres of knowledge should give a reasonable answer to this question.

Since the use of medicinal mushrooms is most well developed in China, and given their very detailed and preeminent system of herbal medicine, Traditional Chinese Medicine(TCM) is the best place to begin. Regarding plant form, traditional practitioners focused on the mushroom fruit body and the sclerotia, which were for all intents and purposes the only parts of the plant that could be harvested. A sclerotium, is a hardened mass of compact mycelial tissue. Poria cocos and Polyporus umbellatus are used in this form. As is common practice in TCM, the mushrooms or sclerotia were decocted, usually as part of a formulation. A decoction, or tea, has the benefit of being concentrated and fast acting. In the case of these fungi, decoctions also break down cell walls, allowing the medicinal components to become available and thereby readily absorbed once consumed.

Most mushroom extracts are made with hot water, which removes the water soluble polysaccharides. The fibrous mushroom remains are discarded and the extract is placed on a carrier material or can be vacuum or spray dried. It has been well established that mushroom polysaccharides are heat resistant. Reishi is unique in that it has a high content of terpenes, many of which are not water soluble. Therefore, many reishi extracts are prepared with a hot water/alcohol blend. The woody fibrous reishi is generally cooked 2-3 times to obtain all the compounds. What remains is also discarded.        

A twentieth century technique for medicinal mushroom production, pioneered by pharmaceutical companies for the production of antibiotics, is fermentation technology or submerged culture of mycelia. This method is being used extensively in Japan and China for the production and refinement of polysaccharides and secondary metabolites from mycelia. It is a logical next step for producing these compounds because it is a highly controlled process that takes less time than growing the actual mushrooms and results in a concentrated extract high in specific medicinal compounds. This methodology is now practised by many mushroom research institutes within China in the development of new mushroom based drugs. Although the development of highly refined drugs is the primary motivation, the initial mycelial extractions, prior to the isolation and purification of specific compounds, fit well within the definition of whole herbal extracts.

Dosages
One of the most difficult figures to determine with any herb is the effective dose. This is no easier with most mushrooms although it is more certain with reishi, Poria and Cordyceps because of their current and traditional use in TCM. It is therefore helpful to begin with traditional use and then consider scientific research and contemporary applications. It should be understood that most scientific research into these mushrooms is carried out in an attempt to define a singular compound responsible for biological activity. Generally speaking, the discovery of purified active compounds is the starting point for the development of pharmaceutical drugs and does not necessarily characterize whole herb activity. This type of research relies initially on animal studies where high doses of active extract fractions are administered, most often by injection, to get quick results. Animal studies are a necessary first step, but are difficult to translate to humans and should be interpreted as a guide rather than an absolute.

The following table gives approximate values as reported from various sources. It should be used as a general reference because amounts will vary depending upon the specific ailment being treated.

mushrooms are decocted in TCM use
*mycelia extract fractions
**pharmaceutical drugS

Conclusions
The current value of edible mushrooms worldwide is 8 billion dollars as recently evaluated by Professor S.T. Chang, chairman of the International Symposium on Mushroom Biology and Mushroom Products held in Hong Kong on August 22-25, 1993. But what surprised participants, myself included, was the statement that medicinal mushroom products were valued at 1.2 billion dollars. The implication was clear, that this use of mushrooms was increasing rapidly and may at some future date rival consumption as food.

So although the use of mushrooms in herbal medicine is in its infancy in the West, their use is now becoming more commonplace and as such, more information regarding their effectiveness in treating disease will become known. We are still just catching up to those areas of the world where herbal traditions remain strong and preventive medicine is an important facet of health delivery systems. As the value of prevention is realized here, these mushrooms will surely be incorporated into our diets and play an important role in our overall health and well-being.

About the Author
Jeff Chilton has been in the mushroom industry for 25 years, is the co-author of The Mushroom Cultivator, and is President of NAMMEX, a company specializing in the production of medicinal mushroom products for the Nutraceutical, Functional Food and Nutritional Supplement Industry.

Copyright ©1993 Jeff Chilton. All rights reserved.