20 Mar 2023
Shiitake mushroom: benefits, uses and side effects
What is shiitake mushroom?
Shiitake is quite unique among medicinal mushrooms in that people prize it for both its flavour and its health benefits. Thanks to its earthy umami taste and firm, almost meaty texture, it’s one of the world’s most popular edible fungi. In addition to eating fresh shiitake, you can consume it in dried, powdered or supplement form.
Although now cultivated around the world, shiitake is native to East Asia. In the wild, it naturally grows on hardwood logs – particularly the Japanese shii tree from which it gets its name. The Latin term for the mushroom is Lentinula edodes, but it’s also referred to as black mushroom and golden oak mushroom.
Despite these names, shiitake is actually more of a brown hue. It has a tough stem topped with an umbrella-like cap that’s usually between 5-10 centimetres wide. There are several different types of shiitake mushroom, with the main varieties being koshin (fragrant) and donko (winter). Koshin mushrooms are more mature, with a larger cap and stronger aroma. Donko, on the other hand, are premium grade mushrooms that have smaller, denser caps marked with white cracks.
Practitioners of traditional medicine systems have been using shiitake for centuries. For example, in China people harnessed it to boost their Qi (life force), circulation, longevity, and overall health. Excitingly, modern scientific research is now finding evidence to back up some of these reported shiitake mushroom benefits. So, let’s take a closer look at how this fabulous fungus can enhance your wellbeing.
How shiitake mushroom benefits your immune system
One of the most notable reasons shiitake mushroom benefits your health is that it could strengthen your immunity. For instance, research has found that consuming the fungus can improve the function of immune cells and decrease inflammation.(1) The latter is important for wellbeing because chronic inflammation contributes to a number of medical conditions, from arthritis to Alzheimer’s.(2)
According to animal studies, shiitake may also be able to reduce or even reverse some age-related decline in immune function.(3) However, further evidence is required to confirm whether these specific shiitake mushroom benefits apply to humans.
Experts believe shiitake’s immunity-boosting effect is thanks to certain polysaccharides that the fungus contains, like beta-glucans. These can enhance the activity of particular types of immune cells, such as macrophages and natural killer cells.(4) Moreover, shiitake is a fantastic source of copper, and this mineral is vital for maintaining optimal immune function.
In addition, polysaccharides may further support immunity by acting as a prebiotic. This means they stimulate the growth of good bacteria in your digestive system, improving the health of your gut microbiome. This is key because both the condition of your gut and the type of bacteria that live there affect the strength of your immune system.(5) The fact shiitake is high in fibre bolsters this effect, as fibre further helps to keep your digestive system healthy.
In line with its positive influence on immunity, scientists are additionally investigating the antimicrobial, antifungal, and antiviral properties of shiitake.(6) It’s possible that compounds from the fungus could help us fight infections, although more research is necessary to clarify this.
Shiitake’s anti-cancer properties
Among the most exciting shiitake mushroom benefits is the fungus’s potential to combat cancer. In particular, one of the polysaccharides it contains – called lentinan – shows a lot of promise in this area. Research has found that it can help to fight tumours, plus inhibit the growth and spread of leukaemia cells.(7) This is partly through shiitake’s ability to activate the immune system, as we discussed above.
Interestingly, studies also demonstrate that using lentinan alongside chemotherapy helps prolong survival and improve quality of life for cancer patients.(8) However, further research is required to ascertain how beneficial fresh or powdered shiitake might be with regard to cancer.
How shiitake mushroom benefits cardiovascular health
Another of the main shiitake mushroom benefits is the positive impact it can have on the health of your heart. There are several reasons for this.
Firstly, shiitake contains numerous compounds that help to lower your levels of cholesterol.(9) These include eritadenine, which reduces cholesterol in the blood, and beta-glucans. The latter may decrease the amount of cholesterol absorbed by the intestines. All of this is important because high cholesterol can clog the arteries and lead to the development of heart disease.
Evidence also suggests that consuming shiitake could help to reduce your blood pressure.(10) This could be thanks to the potassium it contains, which works to relax blood vessels. However, further research is required to confirm this.
Moreover, shiitake mushrooms could help to give you an energy boost. One reason for this is that they’re naturally high in B vitamins such as riboflavin (B2) and niacin (B3). Both are essential for our bodies to produce energy, and fatigue is a common symptom of a deficiency in B vitamins.
Shiitake mushroom benefits: nutrition
Mushrooms such as shiitake are of particular benefit to those who are following a plant-based diet. That’s because they’re one of the few non-animal sources of vitamin D. This nutrient is crucial for building and maintaining strong and healthy bones. The most effective varieties are mushrooms that are grown in sunlight or exposed to UV light.(11)
Shiitake is also a rich source of essential amino acids, including valine, lysine, and threonine. These are crucial for everything from muscle development to hormone production. The body can’t make essential amino acids by itself, so we need to acquire them from our diet. On top of which, the fungus is high in key minerals such as selenium, copper, and zinc.
Other notable shiitake mushroom benefits
Another way shiitake mushroom benefits our health is through its antioxidant properties.(12) The fungus contains potent triterpenoids such as ergothioneine, as well as phenolic compounds like gallic acid and catechin. These can help protect our cells against oxidative stress caused by free radicals. This is key because research has linked oxidative stress to several medical conditions, including Parkinson’s, cancer, arthritis, and cardiovascular disease. It can even spread up the rate of ageing – something we all want to avoid!
Finally, like many medicinal mushrooms, shiitake is an adaptogen. That means it might enable our bodies to cope with all kinds of stress more successfully, from physical to emotional. However, more study is necessary to discover how effective shiitake is in this regard.
