Lentinan is a glucan obtained from Lentinus edodes (shitake). Lentinan has been found to have a positive action against various syngeneic and allogeneic tumours. Similar to other glucans (a polysaccharide obtained from D-glucose), lentinan does not have any direct cytotoxic action on the tumour cells. However, it has been found that an optimal dose of this compound has an anti-tumour action. Nonetheless, the anti-tumour action of lentinan differs between mouse strains and they may be graded either as low or high responders. In physically powerful responder mice, lentinan will absolutely degenerate transplantable fibrosarcomas induced by 3-methylcholanthrene.
It has been found that lentinan is highly effectual against primary tumours induced by methylcholanthrene in mice when used together with cyclophosphamide. Administering this to cancer patients who are in phase I and II trials, scientists have obtained encouraging results.
Different from the actions of glucan, lentinan's anti-tumour activity does not take place in neonatally thymectomized mice or in mice that have been treated with antilymphocytic serum. The anti-tumour activity also does not happen when the mice is treated with whole body irradiation. While lentinan does not help to augment phagocytosis, it has the ability to encourage macrophafe cyctotoxic activity in a living organism (in vivo). Consequently, lentinan's anti-tumour activity may also be blocked by antimacrophage agents like silica or carrageenan.
It is worth noting that lentinan does not speed up the formation of antibody, neither does this compound results in enhanced lymphocytes in the blood, speed up allograft rejection or have any impact on delayed-hypersensitivity reactions.
Way back in 1969, scientists at the National Cancer Center Research Institute in Tokyo were successful in isolating a polysaccharide compound from shiitake mushroom, which they named lentinan.
Researchers have already shown that lentinan stimulates the cells of the immune system to eliminate tumour cells from the body. In clinical trials, it was found that wherein cancer patients were administered lentinan along with chemotherapy, it increased the patients' life span, held back the tumour growth, and enhanced the efficacy of chemotherapy. In Japan, the authorities have approved the use of lentinan as a drug to prolong the lives of people undergoing chemotherapy for stomach cancer.
Some other studies have revealed that when cancerous mice are given a diet comprising 10 percent lentinan, tumour growth is slowed down by about 40 percent. On the other hand, increasing shiitake to comprise 40 percent of their diet, it inhibits the tumour growth by almost 70 percent.
This has led the researchers to conclude that intake of the entire mushroom helps to stimulate the immune cells, for instance the T cells and macrophages and also the natural killer cells. Shiitake encloses compounds that obstruct carcinogen formation from nitrates that are present in some vegetables and several processed meats.
Precisely speaking, lentinan is an herbal remedy that is obtained from the shiitake mushroom, which is widespread in Japan. The shiitake mushroom is basically a fungal growth that generally appears on trees having broad leaves. Usually, this fruiting body has a pale amber-hued stem and gill. Shiitake mushroom is a well-liked ingredient in many Asian cuisines as well as in traditional Chinese medicine (TCM). It is commonly used to perk up the immune system and also to ease the symptoms of various forms of cancer.
The lentinan molecule is made up of several glucose units and they are fund in the cell membranes of shiitake mushroom. A water soluble polysaccharide, lentinan's structure is triple helix. When the structure of lentinan is deformed its beneficial properties are also reduced. This usually happens when the polysaccharide is exposed to heat.
An individual shiitake mushroom contains a very small amount of lentinan and, hence, it does not have any therapeutic utility. Even the cells in our body have a hard time taking up the polysaccharide as the body metabolizes it very quickly. As a result, the potential health benefits of consuming foods made with shiitake mushroom is also reduced. There are also several oral supplements containing shiitake mushroom.
Therefore, using concentrated extracts of this polysaccharide is always a much better way to obtain the health benefits offered by it. These concentrated extracts of lentinan are usually prepared from cultures of shiitake mushroom. Usually, this extract is prepared in the form of a solution and is directly injected into the bloodstream with a view to enhance its absorption by the cells. A dose of lentinan is administered by using an intravenous (IV) line. The typical dose of this extract varies between 2 milligram and 10 milligram per week. It is used for treating people suffering from cancer as well as those who are infected with human immunodeficiency virus (HIV).
Experiments conducted in laboratories have shown that lentinan helps to inhibit the growth of specific carcinogenic cells and it may even induce cancer cell deaths (apoptosis). Further experiments undertaken with lentinan suggest that it has the ability to enhance the immune cell activity - especially immune cells like cytokines, T-cells, monocytes and tumour necrosis factor. It was found that the boosted response of the immune cells obstructed the activities of specific types of viruses and bacteria, including vesicular stomatitis virus and staphylococcus aureus.
Traditionally, people have been holding shitake mushrooms in very high esteem for the nutritional benefits offered by them. These mushrooms are an excellent source of B vitamins and many essential minerals. Researchers have studied these mushrooms for the health benefits they offer, including their anti-carcinogenic properties.
People in Japan and China use lentinan widely in the form of an adjuvant to chemotherapy for treating cancer. In addition, this compound is also used to regulate the immune system.
Although use of lentinan offers us several nutritional and health benefits, people should be cautious while using this polysaccharide as there are reports of several side effects of administering this shiitake mushroom extract intravenously. The most severe side effects of intravenous (IV) use of lentinan include anaphylaxis - an extreme allergic reaction. In addition, it may also cause granulocytopenia - a decrease in the white blood cell type that helps to combat various infections. Usually, this results in chronic bacterial infections of the lungs, throat and the skin.
Presence of high concentration of liver enzymes in the bloodstream is yet another side effect of intravenous use of lentinan - an extract from shiitake mushroom culture. Another condition that may occur following use of this polysaccharide from shiitake mushroom is contact dermatitis. However, the last condition is mainly a worry for people engaged in production of large amounts of shiitake mushrooms as during the process they come in contact with high concentration of lentinan.