The Fungus Among Us

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I have to admit I never thought much about mushrooms. When I did have a thought it was: How can anything that grows that fast have any food value? I also never found them to be big on flavor. Plus, it just seemed kind of gross to put fungus on my pizza. But after reading through the most recent research literature on medicinal plants, I've decided it would behoove me to develop an interest in and a taste for - mushrooms. 

Approximately 700 species are known to possess significant pharmacological properties. The medicinal use of mushrooms originated in the Far East where the traditional cultures of Korea, China, Japan, and eastern Russia have been using decoctions and essences of mushrooms for hundreds of years to treat and prevent disease. Of those, the reishi and shiitake mushrooms have been the first to make it into supplements sold in American health food stores. 

Examining the research literature has made it clear to me that the various compounds in mushrooms act in different ways to promote health and fight disease, often producing a synergistic effect where the sum effect is greater than the added values of individual effects. I also discovered that where most species act by increasing immune responses, making them valuable infection and cancer fighters, some have immune suppressing effects, making them efficient in treating allergies, arthritis and inflammation. At least 651 species contain antitumor and immunostimulating metabolites. 

Although the standard approach to studying mushrooms has been to isolate and administer the pure active constituents, I did come across one population study that looked at eating habits and disease incidence. The study found that greater use of dietary mushrooms (species unspecified) was strongly associated with reduced disease. Since the study was carried out in Korea, it might not be a bad idea to explore the offerings of your local Korean grocer. 

So how do you know which mushrooms to take for what? Most of the mushrooms tested targeted various cancers. The latest up and coming mycological rock star is Agaricus subfrufescens, formerly known as Agaricus blazei. This Brazilian mushroom has a sweet taste and an almond-like aroma. Numerous studies have found it to be effective in cancer treatment by stimulating natural killer cell activity, and assisting in the production of interferon and interleukin. It also reduces side effects of chemotherapy such as appetite, hair loss, and weakness in patients with cervical, ovarian and endometrial cancers (Int J Gynecol Cancer, 2004 Jul-Aug). 

Researchers attribute much of this mushroom's healing power to its beta-glucan content, which has been found to be higher than that in either shiitake or maitake species. Korean researchers describe its effects as "antimetastatic, antitumor, antimutagenic, and immunostimulating" (Biol Pharm Bull, 2007 Aug). I think that just about covers every way that cancer can possibly get a foothold. 

But that's not all. A. blazei (a.k.a. A. subfrufescens) has also been found to fight infections. It can knock out a moderately virulent strain of Streptococcus pheumoniae, and protect against infection (Scand J Immunol, 2005 Oct). Other reports describe its ability to decrease blood glucose, blood pressure, and cholesterol, and to mitigate the effects of arteriosclerosis. Other conditions fought by fungi include asthma, atherosclerosis, and thrombosis. 

Now let me introduce you to a species closer to home: Coprinus comatus. This mushroom is native to the Rocky Mountains and can be easily spotted growing by the roadside. It looks like a lawyer's wig or shaggy mane, and hence is also called by these two names. It is closely related to the Agaricus species mentioned above. Although it gets its genus name by loving to grow in manure, it has been found to fight breast cancer cells in vitro. Both estrogen-dependent and estrogen-independent cells showed marked growth inhibition and cell death when exposed to the extract (Oncol Rep, 2006 Feb). 

This same study also tested Flammulina velutipes, also known as winter mushroom, velvet foot, or by the Japanese name: enoki. I believe the genus name can be attributed to its flaming color. While C. comatus slowed cancer cell colony growth by 66% in two hours compared with untreated cells, F. velutipes reduced cell growth by 99% in the same time. Although F. velutipes can be found growing on dead elm trees, I don't recommend running out and picking them without consulting a mycologist, as they can be easily mistaken for the poisonous species: Galeria autumnalis. 

But let's get real. The medicinal mushrooms you're most likely to find in a store near you would be maitake (Grifola frondosa), shiitake (Lentinula edodes) and reishi (Ganoderma lucidum). While a fraction of the maitake mushroom has been found to induce death in human prostate and bladder cancer cells, extracts of shiitake demonstrated strong antimutagenicity against Hep-2 cells: a cell line established from human laryngeal carcinoma in a 56 year old male (Toxicol In Vitro, 2006 Dec). Reishi has been used for centuries in Asian countries against various cancers. Like maitake, it seems to be particularly effective against prostate cancer. 

At this point the study of mushrooms as therapeutic agents is in its infancy. Many of the studies are still at the level of the test tube and petri dish. And a few animal studies have been done. But judging by the literature, I would say that when it comes to fungus, the scientists are definitely on to something.