Maitake Mushroom: a novel immune enhancer

Original Internist, June, 2002 by Harry Preuss, Debasis Bagchi

Background

Throughout much of the world, extracts derived from maitake and other mushrooms are considered to be frontline medical "drugs," even though the scientific study of mushrooms has only begun during the last 20 years. (1-6) Some mushrooms are rich in minerals (potassium, calcium, and magnesium), various vitamins (D2, B2, niacin, and C), and amino acids, but perhaps the most important ingredients found in maitake are polysaccharide compounds called beta-glucans that exhibit strong immune support activity. (7-25) The maitake mushroom, indigenous to the northeastern part of Japan, is an especially rich source of beta-glucans. (7,13,17) For hundreds of years, indeed for 3000 years, this rare mushroom has been prized in China and Japan not only for it delicious taste but for its health benefits. Common lore states that maitake is so named because people who found it in the deep mountains knew of its luscious flavor and health benefits and thus began dancing with joy. In the feudal era of Japan, the mushroom was excha nged for the same weight of silver by local lords who, in turn, offered it to the shoguns. The botanical name of maitake is Grifola frondosa, a designation that refers to a mythical beast -- half-lion and half-eagle.

Beta-Glucans: An Introduction

Today, many mushrooms are being recognized for their important health benefits. This is primarily because they are an excellent source of beta-glucan polysaccharide compounds that promote well-being. (3) Beta-glucans (also known as [beta]-l,3/1,6-D-glucan or beta1,3/1 ,6-glucan) are non-digestible polysaccharides (long chain carbohydrates) found in the cell walls of maitake mushroom. As with any beta-glucan (or poly-glucose), its [beta]-1,3/1,6-D-glucan consists of multiple glucose units linked together. While common table sugar, a dimer composed of glucose and fructose, may be deleterious to health when consumed in excess, beta-glucans are healthful. Indeed, we need small amounts of beta-glucans for our bodies to function properly. However, these are no longer abundant and scarcely present in our limited, over-processed diets.

Immune Enhancing Functions of Beta-Glucans

When beta-glucans are consumed prudently, one's immune health benefits greatly. Individuals reactivate their immune system, regain their ability to fight disease, and are able to ward off infection. These complex sugars are the basis of multicellular immune intelligence -- the ability of immune cells to communicate, cohere, and work together to keep us healthy and balanced.

How do they work? Beta-glucans have been shown to dock onto receptors on the outer cell walls of macrophages and activate them, so that they can aid us in our fight against cancer and infectious diseases. (26) Macrophages contain specific protein-based receptor complexes on their cell walls to which the [beta]-1,3/1,6-D-glucan molecule readily binds. The binding of [beta]1,3/1 ,6-D-glucan enhances their ability to detect and scavenge a variety of health threats. It may be truly stated that the body's macrophages and beta-glucans were meant for each other. Bacterial infections respond remarkably to these polysaccharides, as do many viral infections from the common cold and flu to herpes and HIV. Beta-glucans even mitigate the toxic effects of radiation and chemotherapy while augmenting their cancer-killing effects, resulting in prolonged survival and improved quality of life for cancer patients. (1,2)

Many biological response modifiers stimulate nonspecific immunity. Among these are various synthetic and biological agents, each with completely different chemical structures. Herbs, such as astragalus, echinacea, and others, have been documented to possess a non-specific immunomodulatory effect. (27,28) In contrast, most of the medicinal mushrooms, such as reishi, shiitake, cordyceps, and maitake, show a common ability to enhance immune function by stimulating cell-mediated immunity. (29) Quite simply, mushrooms seem to turn on cells in the immune system, including macrophages and T-cells that appear to have significant cancer- and infection-fighting properties. It is important to note that while many fungi can be used as a source of beta-glucans, maitake is substantially differentiated from the others because it appears to retain efficacy when administered orally. To use an example, lentinan derived from shiitake must be administered intravenously to be most effective. (29) Accordingly, maitake is the most effective when compared to other mushrooms, can be taken orally, and is completely safe. Also worth noting is that other factors, in addition to specific beta-glucan fractions, present in the crude maitake powder offer many additional health benefits to consumers, including blood sugar control, lowering of cholesterol, high blood pressure reduction, and even aiding weight loss. (30-36)

Today, numerous studies have been conducted on various beta-glucans, and much information can be derived from them. Beta-glucans are classified by scientists as semi-essential, non-vitamin factors and are believed to protect against certain diseases. These polysaccharides are found in other "superfoods," including oats, nutritional yeasts, and other medicinal mushrooms, but the chemical structures of maitake's beta-glucans, especially those found in the D-fraction, are unique due to their greater degree of molecular branching. (6,7) People have known for a very long time that the Monkey's Bench mushroom family, of which maitake is a member, possesses significant anti-cancer effects. Therefore, they have used the ingredients obtained by boiling these substances down as a sort of medicinal hot water treatment for certain cancers. It is now known conclusively that the anti-tumor effects are the result of the activity of various beta-glucans found in the mycelium (which is the mass of interwoven filaments that fo rm the vegetative portion of the maitake mushroom and are submerged in soil or organic matter). (14) Researchers obtained various fractions by continually refining down the elements in the fruiting body of maitake. The results of this research were first published in the l980s. (6-22)