What You Should Know
Lentinula edodes is an edible wild mushroom native to eastern Asia. It grows in the deciduous forests of Asia under warm and humid climatic conditions. The fungus was first described scientifically as Agaricus edodes by Miles Joseph Berkeley in 1877. It was placed in the genus Lentinula by David Pegler in 1976. The shiitake name comes from the Japanese term “shii” which suggests oak and the term “take” which means mushroom.
This a meaty medicinal mushroom that contains protein, B vitamins, lentinan—a polysaccharide complex that stimulates the immune system, and is thought to be responsible for shiitake’s anticarcinogenic properties. Shitake is used for hypertension and to stimulate the immune system in patients with AIDS, cancer, and chronic fatigue syndrome.
Other names: Shiitake Mushroom.
Lentinula edodes Mushroom Identification
The shitake has an umbrella-shaped cap that is tan to brown. The edges of the cap roll down and inwards towards the whitish, cream-colored gills on the underside of the cap. The stem of the shiitake is also white or cream but can turn brown as the mushroom grows larger. Caps grow anywhere from 5 to 15 cm (2 to 6”) in diameter.
From 5 to 8 cm (2 to 4”) tall.
The gills are adnexed.
Shitake grows in groups on the decaying wood of deciduous trees, particularly chinquapin, chestnut, oak, maple, beech, sweetgum, poplar, hornbeam, ironwood, and mulberry. Its natural distribution includes warm and moist climates in southeast Asia.
This mushroom is the second most widely cultivated mushroom in the world. It has been a popular food source in the cuisine of Asia for thousands of years. They are a rich source of copper, selenium, iron, zinc, dietary fiber, and protein. It is also a good source of the B-complex, vitamin C, and vitamin D.
Shitake fruits in the spring and the autumn.
Lentinula edodes Health Benefits
When lentinan, an extract taken from Lentinula edodes, was given to rats as a daily nutritional supplement, the rats saw an increase in circulating white blood cells; these cells are essential for fighting infections. In addition, there was a reduction in molecules associated with inflammation. This demonstrates a potential role for Lentinula edodes in boosting the immune system. Other studies have also provided supporting evidence in the role of this mushroom in enhancing immune defenses.
Antimicrobial (bacterial, fungal and yeast)
Antibiotic resistance by microbes has become an evolving problem with researchers looking to exploit natural products to reinforce the fight against pathogens. Extracts from supermarket-bought Lentinula edodes were tested against a panel of different bacteria, yeast and fungal pathogens and it showed positive antimicrobial against 85% of those it was tested against. Of significance was the positive effects of Lentinula edodes against strains of Pseudomonas and Salmonella bacteria , a good response was also seen against Staphylococcus aureus (MRSA). MRSA is a significant problem seen in hospital environments.
The anti-tumor effects of Lentinula edodes have been observed in several cancers; some studies have been described below. There have been positive reports for breast cancer also; however, the reported effects on pancreatic cancer have been varied.
Lentinan is thought to be one of the major bioactive molecules in the Lentula edodes. The effects of the extract were observed on human colon cancer cells in mice pre-fed with lentinan and a significant reduction in the size of tumor formation was observed in mice that were pre-fed compared to controls.
An analysis of patients with gastric cancer, receiving immunochemotherapy in addition to lentinan (the Lentinula edodes extract) was performed. The results showed that patients receiving conventional therapy in addition to lentinan had a more prolonged survival rate. It was also noted that the results might be more effective in patients with lymph node metastasis (cancer spread to the lymph node) when compared to non-lymph node metastasis.
Twenty-five patients with advanced pancreatic cancer were administered lentinan, and survival times were examined based on a three-year follow-up. 20% of patients (5 out of 25) survived the 3 years, although the median was 12.1 months. There was also a significant relationship between quality of life and lentinan treatment. The evidence is in support of quality of life-enhancement in patients administered compounds extracted from Lentinula edodes.
Liver fibrogenesis is a wound healing process following chronic liver damage, and it can occur following hepatitis viral infection. Too much liver fibrogenesis can lead to unwanted liver cirrhosis. A mouse model representing liver damage showed extracts of Lentinula edodes were able to reduce the fibril forming process. In addition, in vitro, rat liver cells showed that the extract provided protection, in particular through the specific liver cells – hepatic stellate cells, that are involved in liver fibrosis. The authors confirmed the potential for using Lentinula edodes as a safe liver protective agent with few side effects. Furthermore, in humans with hepatocellular carcinoma, the most common type of liver cancer, long-term ingestions of a food supplement with Lentula edodes was shown to increase survival rates in patients.
An in vitro study of bone cells clearly showed that the activity of Lentinula edodes in culture acts as a bone-inducing agent. Therefore, this mushroom deserves attention and further research in its use as a supportive dietary treatment for conditions associated with bone disease including, osteoporosis (a brittle bone disease) and bone complications with late-stage diabetes.
High blood pressure
Research involving a model of hypertensive rats showed that 5% of Lentinula edodes extract for 9 weeks was able to reduce blood pressure levels. These effects do need to be also confirmed in human patients with high blood pressure.
Using a rat model to mimic diabetes, extracts taken from a mycelial culture of Lentinula edodes were able to reduce plasma glucose levels by as much as 21%. In addition, those rats receiving Lentinula edodes had increased insulin levels of 22% compared to the controls; insulin is essential for controlling glucose levels. Importantly, plasma levels of total cholesterol and triglycerides were reduced by 25% and 44% respectively. The dose of Lentinula edodes administered to the rats was 200mg/kg of body weight and shows potential as an agent to control blood glucose, fatty acids and cholesterol levels.
Anti-Cold and Flu
Lentinus edodes is full of beta-glucans, compounds that have been shown to act as antivirals – against hepatitis, HIV and herpes, to name a few. Studies have shown that in vitro extracts of Lentinula edodes can also prevent influenza (flu) virus from growing during the early stages of infection. The possible mechanisms of action include the prevention of entry into the host cell by the virus. Gaining entry to the host cell is essential for the flu virus to be able to reproduce itself and then continue to infect others. This warrants more considerable research, particularly during times such as now with the recent pandemic. Furthermore, the administration of Lentinula edodes by the nose into an infected mouse increased survival rate and administration via the mouth caused an immune response that led to a reduction in the pathological effects of infection, including damage to the alveoli of the lungs.
A protein isolated from the Lentinula edodes mushroom was administered to cells from a mouse cell line representing Leukemia, the extract prevented the ability of these cells to proliferate. This is essential to prevent the continued expansion of these leukemia cells. A further study isolated lentinan – the nutritional supplement from the mushroom and administered it to rats with aggressive Leukemia. Although the Leukemia was not cured, they saw that the general health of the rats was improved, in particular in the levels of wasting and weakness at the end stage of the disease suggesting possible benefits to the quality of life for those with terminal cancer.
In the same experiment as described for Leukemia, the researchers added the Lentinula edodes extract to an enzyme (transcriptase) important for the HIV-1 virus as it enables the virus to reproduce itself. The Lentinula edodes extract was able to prevent the activity of the enzyme, slowing the reproduction rate of the virus.
Photo 1 - Author: Luigi Chiesa (Public Domain)
Photo 2 - Author: Batholith (talk) (Public Domain)
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