September 2011 Issue

Medicinal Mushrooms
By Jasmin Ilkay, MPH, RD
Today’s Dietitian
Vol. 13 No. 9 P. 30

Eastern medicine practitioners have recognized the medicinal properties of mushrooms for thousands of years. Numerous scientific studies conducted in the past 30 years—primarily in Japan, China, and Korea—have evaluated some of the healing capabilities of mushrooms. Therapeutic uses vary, but current evidence primarily focuses on the value of using mushroom supplements as a complementary treatment for cancer and as an immunostimulant. In the United States, mushrooms are typically viewed as a culinary delicacy and have only recently begun to be considered supplements.

Mushrooms are part of the fungi kingdom. Medicinal mushrooms primarily belong to the fungi phylum basidiomycetes. In general, mushrooms are low in fat and calories and high in carbohydrates and protein.1 They also contain thiamine, riboflavin, niacin, biotin, vitamin C, phosphorus, and potassium.1

Many bioactive substances have been identified in the basidiomycetes phylum. These include polysaccharides, glycoproteins, triterpenoids, and fungal immunomodulatory proteins.2 The specific bioactive components vary depending on the species of mushroom and are believed to be responsible for a majority of their reported healing properties.

In addition to reported immunostimulant and anticancer properties, mushrooms used for medicinal purposes are described as having antioxidant, antihypertensive, cholesterol-lowering, antiviral, antibacterial, and antiparasitic effects.

Some varieties of healing mushrooms are edible and others are inedible. Historically, inedible mushrooms with medicinal properties were heated in hot water and made into a tea or broth. Many of the medicinal mushrooms historically used were rare and very expensive. Artificial cultivation of rare medicinal mushrooms has made them more widely available and affordable. Today medicinal mushrooms are mostly grown commercially and available dried or in liquid extract and capsule form.

Promising Medicinal Mushrooms

• Reishi mushroom (Ganoderma lucidum): Historically referred to as the “mushroom of immortality,” Ganoderma lucidum is a large woody mushroom that’s deep red in color with a varnishlike appearance. The reishi mushroom was once extremely rare because it mainly grows as a fungus on decayed plum trees. The mushroom’s bitter taste and woody texture make it inedible. Reishi supplements are primarily marketed as an immunostimulant, anti-inflammatory, antiallergy, or antitumor and as an adjunct treatment for conditions such as HIV, AIDS, and certain cancers.

The Memorial Sloan-Kettering Cancer Center reports that in-vitro and animal studies imply that reishi mushroom supplements have chemoprotective effects, alleviate chemotherapy-induced nausea, and can increase the efficacy of radiotherapy. According to WebMD, the reishi mushroom is possibly safe for most people when used appropriately. Potential side effects include dryness of the mouth, throat, and nasal area along with itchiness; stomach upset; nosebleeds; and bloody stools. It may also interfere with antihyperintensive and anticoagulant/antiplatelet drugs.

• Maitake (Grifola frondosa): This mushroom grows in large clusters that resemble a hen’s tail feathers, hence its nickname “hen of the woods.” Unlike the reishi mushroom, maitake mushrooms are edible. One of the more popular and most researched supplement forms of maitake is the Maitake D-fraction extract. This particular extract is made from maitake mushrooms grown in the mountains of northeastern Japan.3

The key component of the maitake mushroom is beta-glucan (a polysaccharide). Beta-glucan is thought to have immune-stimulating effects as well as the ability to activate certain cells and proteins that attack cancerous cells.3 Animal studies conducted in the late 1990s demonstrated that Maitake D-fraction could enhance the immune system, inhibit tumor growth, prevent the development of cancer in normal cells, lower blood sugar, and lower blood pressure.3 (Placebo-controlled human clinical trials have yet to verify the results seen in animals.)

Not enough information is available regarding potential side effects of maitake mushroom supplements. This edible mushroom is considered possibly safe when used medicinally while following manufacturer’s instructions. It may interfere with antidiabetes drugs because of its ability to decrease blood sugar.4

 • White button mushroom (Agaricus bisporus): Also known as crimini, the white button mushroom has been the staple American culinary mushroom for decades. When fully matured, white button mushrooms grow to become portobello mushrooms.

White button mushrooms have recently been reported to play a role in cancer management. Researchers from City of Hope reported that phytochemicals present in mushrooms block the activity of the aromatase enzyme, which facilitates the production of estrogen.5 Blocking this enzyme would decrease the production of estrogen, which in turn helps control and possibly prevents the growth of hormone-dependent breast cancer cells. City of Hope researchers are currently in the early stages of evaluating the effects of white button mushroom extract on estrogen levels of postmenopausal breast cancer survivors.5 White button mushroom extract also has been found to block the conversion of the enzyme steroid 5-alpha-reductase to dihydrotestosterone.1 Like estrogen is to breast cancer, dihydrotestosterone is associated with an increased risk in the development of prostate cancer1.

White button mushroom extract appears to be safe for most people when taken for up to 12 weeks.6 It may cause hypoglycemia in some people with diabetes, and it can cause itching. In addition, there have been reports of liver toxicity in people who took white button mushroom extract during cancer treatment.6

Historical evidence, use in Eastern medicine, and current research validates the use of some mushroom supplements, particularly as a complementary treatment for cancer and as an immune stimulant. The supplements discussed in this article comprise only three of the hundreds of mushrooms that have medicinal properties. Continued research and product development likely will lead to an increase in mushroom supplement variety and use in the future.

— Jasmin Ilkay, MPH, RD, is a lecturer for the human nutrition and food science department at California State Polytechnic University in Pomona and a freelance writer.


1. Galena AE, Vaghefi SB. Mushrooms and the prevention and treatment of cancer. In: Watson RR, Preedy VR, eds. Botanical Medicine in Clinical Practice. Cambridge, Mass.: CAB International; 2008:293-299.

2. Chang S, Miles PG. Mushrooms: Cultivation, Nutritional Value, Medicinal Effect, and Environmental Impact. 2nd ed. Boca Raton, Fla.: CRC Press; 2004:39-51.

3. American Cancer Society. Maitake mushroom. Last updated November 1, 2008. Available at:

4. WebMD. Maitake mushroom. Available at:

5. City of Hope. Anticancer effect of mushrooms demonstrated. ScienceDaily. June 4, 2011. Available at:

6. RxList. Agaricus mushroom. 2009. Available at: