For culinary use, shiitake are one of the most common and popular mushrooms — their distinctive, savory, and rich taste improves almost any dish. But shiitake mushrooms are much more than a delicious addition to a good meal. The nutritional compounds in shiitakes provide a vast array of health benefits.
Packed with fiber, vitamins, minerals and dozens of phytonutrients — substances in certain plants which are considered beneficial to human health and disease prevention — the shiitake has long been a staple of Eastern medicine. Only recently has modern Western science started to appreciate this mushroom’s contribution to improved health and disease fighting.
What Are Shiitake Mushrooms?
Shiitake mushrooms — scientific name Lentinula edodes and also referred to as black forest mushroom — grow primarily throughout East Asia in countries such as Vietnam, Thailand, Japan, Korea, and China. Over 80% of shiitake are grown in Japan, though a few countries outside of East Asia, such as the United States and Canada, also produce them some. Shiitake are tan to dark brown in color, with caps that grow up to 4 inches in diameter. Shiitake grow naturally on fallen and decaying hardwood trees.
When it comes to describing how shiitake mushrooms taste, the word umami is often used. Umami is the fifth basic taste category (the others being sweet, sour, bitter, and salty), and is best defined by the word savory. Shiitake taste closely mimics beef, and for this reason it’s an ingredient popular with many vegetarians. Once cooked, the mushrooms’ earthy, buttery flavor comes out, along with its pine-like and garlic aroma. In many areas of East Asia these mushrooms are a staple ingredient in dishes such as miso soup, pho, and vegetarian stir-fries.
Shiitake Mushrooms Health Benefits
Centuries ago East Asians discovered that in addition to shiitake tasting great, these mushrooms also have many medicinal properties that can play a role in preventing and treating a number of health concerns. References to the use of shiitake mushrooms for boosting health and longevity can be found in traditional herbal medicine texts written well over a thousand years ago. Only recently has the Western world started to appreciate the health benefits of shiitake.
Nutritionally, shiitake mushrooms are a good source of key minerals and vitamins, including vitamin D, copper, and selenium. Shiitakes contain several compounds known for their roles in immune system support and defense against cancer: polysaccharides, terpenoids, sterols, and lipids. This mushroom also contains a plentiful amount of linoleic acid, an essential fatty acid that contributes to both muscle building and weight loss.
Speaking of muscle building, shiitakes are unique in the plant world because their composition has 18 amino acids, including all eight essential amino acids. Not only that, but these essential amino acids exist in a ratio to one another that is very similar to the ratio of an “ideal protein” for humans. These amino acids, in this particular ratio, are normally found only in meat — providing another reason for shiitakes being popular with vegetarians (the other reason being their meat-like taste).
Shiitake Aids Heart Health
Worldwide, cardiovascular disease is the most common cause of death. Cardiovascular disease is a major health concern because it may lead to aneurysms, heart attacks, and strokes. The disease primarily develops from atherosclerosis — the process where high levels of cholesterol cause a build-up of fat substances on the inside of blood vessels, reducing blood flow to organs such as the heart. Shiitakes can play a key role in heart health, primarily due to three cholesterol-reducing compounds in this mushroom: eritadenine, sterols, and beta-glucans.
Eritadenine is a chemical compound that that has hypocholesterolemic activity. Hypocholesterolemic is the medical term for a compound or medication that reduces plasma cholesterol levels. There are very few natural sources of eritadenine, and of those, the shiitake is the primary source.
Sterols are substances similar to cholesterol, but are produced naturally in plants. Because sterols have a chemical structure similar to that of cholesterol, they are absorbed by the gut in a manner similar to how the intestines absorb cholesterol. This has the effect of reducing intestinal cholesterol absorption. Rather than being absorbed by the gut, much of the cholesterol is passed out of the body in feces. The lower intestinal cholesterol levels also has the positive effect of interfering with cholesterol levels in the liver.
Beta-glucans (also written as β-glucans) are a type of fiber that have cholesterol-lowering properties. It’s believed beta-glucans achieve this by forming a viscous layer in the small intestine. The viscous (a sticky substance with a consistency between a solid and a liquid) layer reduces the uptake of intestinal cholesterol, resulting in lower levels of cholesterol circulating in the blood. Shiitake mushrooms are rich in beta-glucans (as are chaga mushrooms).
Shiitake Reduces Obesity
Shiitake mushrooms contain compounds that have fat-reducing properties. Two of these compounds — eritadenine and beta-glucans— are discussed just above in the Shiitake Aids Heart Health section.
Beta-glucans are soluble dietary fibers, and as such can reduce appetite and in turn reduce food consumption. Eating less food is certainly one way to lose weight! Beta-glucans also delay nutrition absorption and lower plasma lipid (fat) levels.
Eritadenine is a compound that reduces blood cholesterol levels, which is good for heart health. Eritadenine also reduces fat levels by stimulating circulation and metabolism. This reduction in visceral fat (deep abdominal fat) and saturated fat (stored in fat tissue and blood vessel walls) can contribute to weight loss.
A study published in the Journal of Obesity was conducted to note the effects of shiitake mushrooms on fat distribution, blood lipid levels, and body fat index. Researchers determined that shiitake mushrooms can help prevent body weight gain as well as lower cholesterol.
Shiitake Fights Cancer
While shiitakes certainly are not a miracle cure for cancer, these mushrooms do contain specific compounds that can contribute to the defense against cancer and can also minimize the size of tumors.
Polysaccharides are carbohydrates that are built from monosaccharides (simple sugar such as glucose). Shiitake mushrooms include polysaccharides that have anti-cancer properties. The polysaccharide lentinan found in shiitake in particular is a powerful tool in terms of fighting cancer.
Lentinan can both slow the growth of leukemia cells as well as prevent them from spreading. It’s common practice for physicians in Japan and China to prescribe injectable lentinan as one part of stomach cancer treatment in order to boost the immune system.
A study published in the Journal of Alternative and Complementary Medicine examined the roles of a component of ethyl acetate found in shiitake mushrooms. This particular ethyl acetate compound has high levels of polyphenols — plant compounds that offers various health benefits. The study results implied that shiitake mushrooms were able to restrain or prevent growth in tumor cells and induce cancer cell apoptosis — the process of programmed cell death.
Ergothioneine is a powerful antioxidant produced only by select bacteria and fungi — including shiitake mushrooms. Shiitake is a very common part of the diet of many people in Japan, so in general ergothioneine levels in this group is higher than people outside of Japan. A 2019 study of tens of thousands of Japanese men between ages 40 and 80 determined there was a correlation between shiitake consumption and lowered incidence of prostate cancer. The researchers concluded that ergothioneine was the cause.
Shiitake Boosts the Immune System and Fights Inflammation
Inflammation is closely linked to immune system health. Gut problems, joint pain, weight gain, fatigue, anxiety and depression, and acne are some of the health concerns that result from chronic inflammation and a compromised immune system.
Beta-glucans (β-glucans) — introduced in this article’s Shiitake Aids Heart Health section — are a type of dietary fiber with cholesterol-lowering properties. The beta-glucans found in shiitake also play a role in inflammation and immune system health.
One clinical trial determined that the beta-glucan in shiitake mushrooms helped study participants increase their B cells. B cells — also called B lymphocytes — create antibodies which bind to pathogens and toxins to neutralize them.
Polysaccharides such as the lentinan found in shiitake — discussed in this article’s Shiitake Fights Cancer section — are complex sugars with anti-cancer properties. Lentinan has also been shown to be beneficial to the immune system.
A study involving over 50 healthy participants focused on the immune-supporting benefits of shiitake mushrooms. The study concluded that shiitake improved immune function in a few ways:
- Increased immunoglobulin A (IgA) production: IgA is an antibody that is considered the first line of defence in fighting infections
- Decreased levels of C reactive protein (CRP): CRP is a substance produced in the liver and coincides with the body producing inflammation
- Improved cell activation: Activating (“turning on”) B lymphocytes improve the immune system’s toxin-fighting abilities
How to Consume Shiitake Mushrooms
When cooked, shiitake mushrooms are one of the most delicious tasting of all mushrooms — the culinary options for shiitake are near endless. If you can’t find fresh shiitake at your grocer, or you don’t care for the taste of mushrooms, or you want to take a convenient, concentrated daily dose of this fungi (that hasn’t lost any of its potency in the cooking process), then a powdered supplement is your best option.
Shiitake mushroom extract is available as a powder in capsules or as a bulk supplement that you consume by adding a scoop to your preferred drink, such as a juice or smoothie.
The daily recommended dosage of shiitake is 1 to 2 grams per day (1000 mg to 2000 mg).
Shiitake Mushrooms Side Effects
Shiitake mushrooms are considered very safe, with no known severe side effects. Very few people have a sensitivity or allergy to shiitake mushrooms. In those rare instances of a sensitivity, the side effects will be fairly mild — typically the person will experience a slight allergy where the skin may feel itchy or uncomfortable.
Shiitake Mushrooms During Pregnancy
If a person does not experience any side effects from shiitake when not pregnant, it’s extremely unlikely that person will notice any side effects when pregnant. Shiitake mushrooms are considered very safe to eat during pregnancy.