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 defense has led researchers to minerals, plants and fungi in search of natural health-supporting properties. The fungi family in particular shows promise for its ability to enhance immune function.
Mushrooms grow wild in many parts of the world and are also commercially cultivated. Nutritionally, mushrooms are a valuable health foodâlow in calories and carbohydrates; healthy in vegetable proteins and essential amino acids; a source of some fiber; and rich in a number of important vitamins and minerals, including B vitamins, selenium, iron, potassium and zinc.1
Mushrooms have been used medicinally for centuries 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 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 erinaceus), Auricularia auricula-judae and Coriolus versicolor.2,3,4,5,6
Researchers recently studied some of the isolated chemicals from a number of Basidiomycetes mushroomsâa 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, antitumor, antiparasitic, cardiovascular and hypercholesterolemic effects.7,8,9,10 In fact, mushrooms have an impressive effect on the cardiovascular system. Researchers have found that numerous varieties such as maitake, shiitake and cordyceps 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 also 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 helps support and enhance overall immune function. Researchers are also finding that mushrooms can directly stimulate both the basic (lymphocyte, neutrophils, etc.) and secondary immune responses (immunoglobulins IgE, IgA, IgG) of the immune system. This leads to increased production of immune defenders such as macrophages and cytokines, which play vital roles in recognizing and removing foreign antigens, as well as releasing chemical mediators including interleukin-1.
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 generalized 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 such as gram-negative streptococcal and herpetic virus microbial infections and disease states 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.16,17,18,19 Many of these bioactive substances, through their stimulatory effects on the immune system, are showing powerful antitumor, antimutagenic and anticancer activity.20
Beta-glucan is isolated from shiitake and maitake mushrooms,21 as well as from yeast cell walls22,23 and from oat and barley bran.24 It has 1,3- and 1,6-glucose links. The 1,3 refers to the sites at which glucose molecules are connected to form the glucan backbone. The 1,6 refers to the bonding sites between a glucose molecule on the backbone and on the side chains.
Beta-glucan binds to macrophages and other phagocytic white blood cells at certain receptors and activates their anti-infection and antitumor 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 tumor cells.26
Three separate multicenter, randomized, double-blind, placebo-controlled clinical trials have been conductedâtwo at Harvard Medical Schoolâusing 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 percent 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 tumor-inhibiting effects have led to a recent surge of 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 antitumor 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, I recommend a combination of mushroom products (vs. a single mushroom type), preferably from an extract rather than an unprocessed whole mushroom. Certainly, incorporating whole mushrooms in the diet is important, but to achieve greater and more specific immune enhancement, standardized extracts are needed. A combination of different medicinal mushrooms offers both the generalized 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. Researchers are providing crucial data on the array of bioactive chemicals found within these fascinating fungi. More research is certainly warranted, but it appears mushrooms hold potential for improving human health and immunity.
Raymond M. Lombardi, D.C., C.C.N., is a certified herbalist with a holistic practice in Redding, Calif. He is author of Aspirin AlternativesâThe Top Natural Pain-Relieving Analgesics (BL Publications, 1999).
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31. Fujimiya Y, et al. Tumor-specific cytocidal and immunopotentiating effects of relatively low molecular weight products derived from the basidiomycete, Agaricus blazei Murrill. Anticancer Res 1999 Jan-Feb;19(1A):113-8.
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Natural Foods Merchandiser volume XXIII/number 9/p. 38, 40, 45
Natural Foods Merchandiser volume XXIII/number 9/p. 38
Natural Foods Merchandiser volume XXIII/number 9/p. 40