Natural Remedies A-Z
Medicinal Mushrooms - The New Addition to Western Herbal Medicine |
Medicinal fungus have been used for millenia in the traditional medical practices of the Orient. So revered where these fungi that their usage was often exclusively retained for the Emperor and aristocricy. Fungus such as Ganoderma lucidum (resihi, ling zhi) were believed to be an elixir of life, capable of doubling ones life span and warding off all disease and the ageing process. Over the past thirty years the west has become switched on to these amazing healing tools, and they have become some of the most widely and vigorously researched natural products to date and have found their way into conventional medical treatments. This great volume of attention has arisen in response to continued findings that they may be profound allies in some of today’s gravest diseases. The most important being those where the immune system is invloved.
Research has indicated time and time again that medicinal mushrooms are able to instigate a stimulatory effect on various branches of the immune system. The early research on these fungi revealed that their polysaccharide content was responsible for this stimulatory action. These large branch-chained sugar molecules are also known to be present in the widely used immune tonics Echinacea spp and Astragulus membranaceus. The most widely distributed polysaccharides in medicinal fungi, and certainly most widely studied are the Beta-glucans. It is theorised that these molecules are very similar in structure to membrane bound polysaccharides of various cellular pathogens and, as a result, dupe the immune system into instigating a response. In the late 1980’s, the Japanese mycologist Hiraoki Nanba discovered that the mushroom Grifola frondosa (maitake) was capable of delivering the strongest stimulatory response. It was later found that this was due to maitake having a very uniquely shaped polysaccharide, and this was particularly active when given in oral dosages - very useful to the modern day Herbalist and Nutritionist. It is interesting to note however that these polysaccharides are infact too large and dense to be absorbed by the gut! It is believed therefore that these substances may be active by interacting with the white cell dense peyers patches within the gut, causing an alarm response, then cascade reaction and instigating the immune response systemically. In light of Nanba’s research, fungal polysaccharides became heavily studied, and many were patented and developed into pharmaceutical drugs. The most famous of these is PSK, extracted from the Coriolus versicolor (turkey tail) mushroom, which was used in the treatment of cancers in the United States.
So what exactly do these substances effect within the immune system? It is well established that their effect is of a stimulatory nature, but the stimulation of what? The answer is non-specific immunity. Many of the initial studies carried out on mushroom polysaccharides revealed an increase in number, and activity of NK cells. These cells move through the body and seek out any problematic cells in any tissue. These can be cells infected with a virus, or cells that are becoming cancerous. These cells will identify themselves by displaying certain chemical structures on their outer surface - essentially a distress failr. When an NK cell identifies a cell as abnormal it binds to it, then using a substance called perforin, it perforates the membrane of that cell and induces apoptosis (cell death). Another method that NK cells use to induce apoptosis, is by sending a signal through the cell membrane of the affected cell to its nucleus in order to programme its death. Some of the original studies performed by Hiraoki Nanba on Human subjects with various cancers, showed an average increase in NK cell numbers of 1.7 times. It is interesting to note that there was also a decrease in metastasis in test subjects.
Another interesting influence upon the immune system that has been rather heavily documented is the effect upon Th cell subsets. T cells move through the body in an inactive (virgin, Th0) state, until they are activated by an antigen presenting cell. Once activated they differentiate themselves into two subsets which are different in regards to the cytokines (messenger chemicals) that they secrete. These subsets are Th1 and Th2. The Th1 subset of T cells secrete cytonkines that include IL-2 and TNF. This type of response stimulates and primes macrophages, and activates NK cells. This type of response also discourages inflammatory responses and antibody mediated immune responses. Th2 stimulates the type of responses that are antibody mediated and encourage inflammatory reactions. It is this type of response that is involved in allergic reactions. These two Th subsets are mutually inhibitory, so if T cells are stimulated to switch to one subset, any responses attributable to the opposing subset will be supressed. It has become clear from a considerable body of evidence that mushroom polysaccharides stimulate T cells, increase their numbers, and cause these cells to move into the Th1 subset.
These findings clearly suggest several potential uses for these wonderful fungi. The first, and one that has already been at the centre of a vast number of studies, is a role in cancer treatment. The stimulation of NK cells via the Th1 subset is what gives this credibility. As previously described, NK cells have the ability to identify cancerous cells, and destroy them. NK cells are by no means the only cells capable of this action, but cancer cells are somehow able to hide themselves from the other cells of the immune system, but from NK cells there is no escape. There is also an obvious use in the management of HIV/AIDS. This is due to the stimulation in T cell production. This application has been used with considerable success by Marijke Pfeiffer in a European outpatient clinic, and several London based hospital outpatient units. There is also a potential (but currently greatly under-researched) use in the management of allergies and auto-immune conditions. These both rely on the presence of antibodies, and therefore antibody mediated immune responses are responsible for the destructive effects observed in such conditions. As the Th2 subset is mostly responsible for antibody mediated reactions, and because Th1 and Th2 are mutually inhibitory, stimulating Th2-Th1 shift will reduce the ocurrence of these destructive reactions. Martin Powell of MRL has used Ganoderma lucidum successfully in this context, with severe hayfever suferers becoming almost asymptomatic after several weeks supplementation.
We are certainly in the early days when it comes to the use of medicinal mushrooms in western herbal and nutritional practices. However, because of the type of responses highlighted above, many more practitioners are including them in their dispensaries and treatment regimes. There are some wonderful products on the market now for nutritionist and herbalist alike. Mycology Research Laboratories (MRL) have a wonderfully effective range of mushroom tablets at a reasonable price, and Proline Botanicals are now producing tinctures of Ganoderma lucidum, Coriolus versicolor, Grifola frondosa, and Lentinus edodes.
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