The stress and pressure of modern society take a toll on immune system health. Those with weakened immunity are more susceptible to infection and disease. The need to maintain or rebuild a healthy defence has led researchers to minerals, plants and fungi in search of natural health-supporting properties. The fungi family in particular is showing promise for its ability to enhance immune function.
Mushrooms grow wild in many parts of the world and also are commercially cultivated. Nutritionally, mushrooms are a valuable health food - low in calories and carbohydrates; loaded with vegetable proteins and essential amino acids; a source of some fibre; and rich in a number of important vitamins and minerals, including B vitamins, iron, potassium, selenium and zinc.1
Medicinal mushroom varieties
Mushrooms have been used medicinally for centuries, particularly in traditional Chinese and Japanese medicine. In many Asian cultures, mushrooms are used to promote good health and vitality and to increase the body's adaptive capabilities. Although the nutritional facts and culinary uses of mushrooms are well accepted in the West, the fungi's medicinal qualities have yet to make it into the mainstream.
Of the hundreds of known mushroom varieties, several have been studied for their ability to enhance the human immune system and fight infections. Some well-known medicinal mushrooms with benefits for the immune system include reishi (Ganoderma lucidum), shiitake (Lentinus edodes), maitake (Grifola frondosa) and cordyceps (Cordyceps sinensis). Some of the less familiar mushrooms include bai mu erh (Tremella fuciformis), fu ling (Poria cocos), zhu ling (Grifola umbellata), lion's mane (Hericium erinaceums), Auricularia auricula-judae and Coriolus versicolor.2-6
Science-backed mushroom benefits
Researchers recently studied some of the isolated chemicals from a number of Basidiomycetes mushrooms - a large group of fungi whose members range from the familiar button mushroom to rusts and smuts that sometimes ravage crops. The constituents show promising immune-modulating, antibacterial, antiviral, antitumour, antiparasitic, cardiovascular, and hypercholesterolemiac effects.7-10 In fact, mushrooms have an impressive effect on the cardiovascular system. Researchers have found that numerous varieties such as maitake, shiitake and cordyceps sinesis can reduce total cholesterol levels, reduce the bad cholesterol (low-density lipoproteins) and triglycerides, decrease platelet binding and reduce arterial pressure.11 Mushrooms also can affect glycemic levels and inflammatory conditions.12
In addition to these promising preliminary findings, scientists have noted that mushrooms have definite primary and secondary physiological effects on the human immune system. Israeli researchers noted in 1999 that cellular components and secondary metabolites of many mushrooms affect the immune system of the host and therefore could be used to treat a variety of disease states.13
Medicinal mushrooms' powerful immune-modulating and potentiating activity help support and enhance overall immune function. Researchers also are finding that mushrooms can directly stimulate both the basic (lymphocytes, neutrophils, etc.) and secondary immune responses (immunoglobulins IgE, IgA, IgG) of the immune system. This stimulus can increase production of immune defenders such as cytokines and macrophages, which play vital roles in recognizing and removing foreign antigens, as well as releasing chemical mediators including interleukin-1.
Bioactive chemicals in mushrooms
In recent studies on medicinal mushrooms, researchers have used modern analytical and laboratory techniques to significantly improve isolation and identification of bioactive chemicals. These techniques have revealed mushroom substances with antimicrobial activity. A 1999 study in Japan found three kinds of antibacterial substances in shiitake mushrooms that were effective against Streptococcus spp., Actinomyces spp., Lactobacillus spp., Prevotella spp. and Porphyromonas spp. of oral origin.14 A study in Spain found that 45 percent of 317 isolated (extracted) substances from 109 polypore and gilled mushroom species showed antimicrobial activity.15 Some mushrooms have generalised antimicrobial effects, while others have quite specific properties. This dual capability is important because it provides two separate methods of immune enhancement and response, which is important for treating specific microbial infections and disease states such as gram-negative streptococcal and herpetic virus microbial infections, such as sarcoma cancers, leukemia and hepatitis.
Substances that have been found to potentiate the immune system include beta-glucans, lentins, polysaccharides, polysaccharide-peptide complexes, triterpenoids, nucleosides and other secondary metabolites.16-19 Many of these bioactive substances, through their stimulatory effects on the immune system, are showing powerful antitumour, antimutagenic and anticancer activity.20
Beta-glucan is isolated from shiitake and maitake mushrooms,21 as well as from yeastcell walls22,23 and from oat and barley bran.24 Beta-glucan binds to macrophages and other phagocytic white blood cells at certain receptors and activates their anti-infection and antitumour activity by stimulating free radical production.25 This, in turn, signals the phagocytic immune cells to engulf and destroy foreign bodies, be they bacteria, viruses or tumour cells.26
Three separate multicentre, randomised, placebo-controlled, double-blind clinical trials have been conducted - two at Harvard Medical School - using beta-glucan on patients undergoing high-risk major abdominal and thoracic surgery or high-risk gastrointestinal surgery. Patients in one study who received high-dose beta-glucan (2.0 mg/kg) had significantly fewer postoperative infectious complications compared with placebo.27 In another, beta-glucan patients experienced 1.4 infections per patient vs. 3.4 infections in the placebo group.28 In the third study, of 1,249 patients, beta-glucan patients had a statistically significant 39 per cent reduction in serious infections and death compared with placebo.29 The investigators concluded that beta-glucan was safe and well tolerated and could potentially decrease postoperative infections.
Medicinal mushrooms' potential tumour-inhibiting effects have led to a recent surge in research in this particular area.30-31 In a 1999 study in Japan, researchers isolated a polysaccharide from the mushroom hime-matsutake (Agaricus blazei Murrill) that proved to have antitumour effects against sarcoma 180.32 In a mouse study, other researchers investigated the antimutagenic effects of the same mushroom. They concluded that antimutagenic activities of hime-matsutake, under certain circumstances, might contribute to its anticarcinogenic effect.33
Umbrella of protection
The growing body of scientific evidence indicates that mushroom extracts and derivatives support the immune system. For wellness and general health effects, a combination of mushroom products (vs. a single mushroom type) is recommended, preferably from an extract rather than an unprocessed whole mushroom. A combination of different medicinal mushrooms offers both the generalised and specific immune system benefits. For example, a formula that includes some combination of reishi, shiitake, cordyceps, fu ling, lion's mane, bai mu erh, and zhu ling extracts can be taken frequently or even daily to enhance the immune system. As powerful immune modulators and potentiators, medicinal mushrooms are contraindicated for a number of autoimmune conditions such as systemic lupus erythematosus and collagen autoimmune disorders.
Medicinal mushrooms' value to human health is beginning to gain acceptance as researchers provide data on the array of bioactive chemicals found within these fascinating fungi.
1. Mattila P, et al. Contents of vitamins, mineral elements, and some phenolic compounds in cultivated mushrooms. J Agric Food Chem 2001 May;49(5):2343-8.
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Doctors speak on mycological medicine
"In times when we are faced with increased bacterial and viral diseases and higher levels of immune stress, it is refreshing to read such an elegant review of the biological properties of medicinal mushrooms. The author provides information concerning the health benefits of these mushrooms and some of the experimental data that supports their claims of immune-modulating activities.
"It is clear that the use of the medicinal mushroom extracts has its place in the management of certain chronic conditions, including cancer. However, the author does point out that the use of such extracts is not advocated in certain conditions, such as autoimmune states. This is a well-founded warning because these extracts enhance the functioning of the inflammatory cells, and boosting the activity of such cells is not advisable when chronic inflammation forms part of the disease pathogenesis. Furthermore, human clinical trials with clearly defined endpoints of efficacy are lacking at present."
- Patrick JD Bouic, Ph.D., is director of immunology at Tygerberg Hospital, South Africa. For 14 years he has researched plant-derived molecules having immune-modulating properties, particularly for clinically managing infectious diseases.
"When used appropriately - as in the treatment of life-threatening bacterial infections - antibiotics are true wonder drugs. But their appeal as potential magic bullets has been too great to resist, and overworked medical doctors now write millions of unnecessary prescriptions for coughs, runny noses and fevers. In this well-documented article, Dr. Lombardi suggests that medicinal mushrooms, along with other widely available immune-enhancing supplements, can provide a viable alternative to this dilemma.
"Having played a central role in traditional Chinese medicine for thousands of years, medicinal mushrooms may be the first functional foods. In the Orient (and increasingly in the West) these ancient remedies have become immensely popular - some 2.5 million metric tons of medicinal mushrooms are produced each year, constituting $1.5 billion in sales. Lombardi is right that the future is in standardized extracts - the most effective way to harness their remarkable health benefits."
- Robert Rountree, M.D., has been practicing integrated, holistic medicine in Boulder, Colo., for 20 years. He is co-author of Immunotics: A Revolutionary Way to Fight Infection, Beat Chronic Illness, and Stay Well (Putnam, 2000).