Shiitake mushrooms are some of the most popular edible mushrooms in the world. And that’s not just because of their distinctive buttery to smoky taste. In fact, you may call shiitakes medicinal mushrooms too, because they’ve been a revered part of traditional Chinese medicine for hundreds of years. But what are these shiitake mushroom health benefits, and are they fact or fiction? Read on to find out.
A Brief History of Shiitake Mushrooms
Shiitake mushrooms (Lentinula edodes, formerly Lentinus edodes) are native to East Asia, where they’ve been cultivated for almost 1,000 years. The word shiitake comes from a combination of shii, the tree on which the mushrooms are typically grown—the Japanese chinquapin, or shii, tree—and take, the Japanese word for mushroom.
Shiitake mushrooms grow at the base of decaying trees or on hardwood logs, often clumped together in an escalating mound of mushrooms. While they’re traditionally grown on shii trees, they can also be found on the decaying logs and stumps of many other trees, including oak, maple, chestnut, poplar, beech, and aspen.
As the mushrooms age, their umbrella-shaped caps begin to flatten out and take on the rich, earthy color most people associate with shiitakes. However, some people prefer to harvest the fungi when they’re still young and their caps haven’t yet begun to flatten out, as shiitakes become less tender with age. The same also holds true for their stalks, which are quite tender and edible when shiitakes are young but become tough and woody as they mature—though the mature stalks are often used to create hearty vegetable stocks.
With their meaty texture and savory flavor, shiitake mushrooms have become one of the most popular mushrooms available today, making up approximately a quarter of all mushrooms produced in the world. They’re also the third most popular mushroom sold in the United States.
But shiitake mushrooms aren’t just a pretty face, er, fungus, and you want to know about the many health benefits of shiitake mushrooms. So let’s take a closer look at some of these now.
Shiitake Mushroom Health Benefits
The health benefits of shiitake mushrooms begin with their many vitamins and minerals. In fact, shiitakes are rich in several key nutrients, including riboflavin, niacin, copper, pantothenic acid, vitamin B6, selenium, manganese, and zinc.
Shiitake mushrooms also contain eight of the nine essential amino acids, including lysine, an amino acid that’s often lacking in diets that consist mainly of vegetable protein. This makes shiitakes a welcome addition to the typical vegan or vegetarian diet.
But their nutritional value doesn’t end there.
Shiitake mushrooms are also low in calories and good sources of dietary fiber, both of which make these mushrooms a good choice for people interested in maintaining or losing weight.
Inflammation and Immunity
Shiitake mushrooms are great sources of antioxidant-rich phytochemicals—substances that are known to fight free radicals and reduce oxidative stress, high levels of which are linked to inflammation. Because excessive inflammation is implicated in many chronic diseases, including heart disease, diabetes, cancer, and dementia, the anti-inflammatory properties of shiitakes could prove useful in the fight against chronic disease.
A study published in the Journal of the American College of Nutrition found that participants who ate shiitake mushrooms every day for 4 weeks had decreased levels of inflammation and markers indicating improved immune function.
Studies have also found that shiitake mushrooms possess antimicrobial properties that may offer even more benefits for a healthy immune system. What’s more, several studies have found that shiitakes have potent antibacterial and antifungal properties and are even effective against HIV and leukemia.
Shiitake mushrooms may help lower cholesterol and blood pressure—two important factors in heart health. Not only do compounds in shiitake mushrooms inhibit the production of LDL cholesterol (the so-called “bad” cholesterol) in the liver, but they can also help prevent potentially dangerous plaque from building up on the walls of blood vessels. And they appear to do this via the action of three specific substances:
Eritadenine works by inhibiting the production of cholesterol, while sterols prevent the absorption of cholesterol in the GI tract. And beta-glucan is linked not only to improved cholesterol levels but also to lower blood sugar, better immune function, and decreased risk of various types of cancer.
Speaking of which…
A study in the Journal of Alternative and Complementary Medicine found that a beta-glucan polysaccharide in shiitake mushrooms called lentinan has the ability to block tumor growth in mice implanted with human colon cancer cells.
And another study in the same journal found that a shiitake mushroom extract inhibited the growth of cancer cells and even induced cell death in both breast cancer and myeloma.
Shiitake mushrooms contain significant amounts of vitamin D—a hormone necessary for the formation of strong bones and teeth. This is a property shiitakes share with other mushrooms, as fungi are the only known plant sources of vitamin D.
And studies have found that exposing shiitake mushrooms to UV light increases their levels of vitamin D. In fact, one study found that mice supplemented with calcium and shiitake mushrooms exposed to UV light had significantly higher bone density.
Cooking with Shiitake Mushrooms (and Possible Side Effects)
Whether you choose fresh shiitake mushrooms for their buttery richness or opt for the smoky flavor of dried shiitakes, these hearty mushrooms are perfect in pasta, risotto, soups, stir-fries, and pretty much any recipe that calls for mushrooms.
However, if you’ve experienced side effects with other types of mushrooms, it’s possible you could experience a reaction to shiitake mushrooms as well. That being said, most people have no problems with shiitakes unless they eat an excessive amount, in which case nausea, vomiting, and abdominal pain may occur.
Interestingly, another condition associated with the consumption of shiitake mushrooms is shiitake dermatitis—a reaction that may occur 1 to 2 days after eating the mushrooms. People with shiitake dermatitis experience a linear rash that disappears on its own within several weeks.
The condition is extremely rare and thus hasn’t been fully studied, but it’s thought to be the result of a reaction to lentinan—the same polysaccharide that’s been found to block tumor growth.
Some people have also been found to develop photosensitivity after eating shiitakes, with sensitivity to sunlight sometimes accompanying episodes of shiitake dermatitis.
In addition, a 1998 study found that intake of 4 grams (about 1/4 cup or approximately one mushroom) of shiitake mushrooms every day over the course of 10 weeks resulted in eosinophilia—an elevation of certain white blood cells—which disappeared after the mushrooms were removed from the diet.
Again, it’s important to remember that these types of reactions are uncommon and typically occur only with excessive or daily ingestion over a period of several weeks—more than most people are likely to experience in the average diet.
However, anyone taking a shiitake mushroom dietary supplement should keep an eye out for adverse side effects and speak with a qualified health care provider if they run into any issues.
While some of these potential side effects may make you raise an eyebrow (or two), if you’ve been thinking about giving these East Asian natives a try, we say go for it.
Shiitake mushrooms make a great addition to any diet, and with more and more studies demonstrating the myriad health benefits of shiitakes, we think you may just find one more reason to pick some up the next time you drop by your local grocery store.