Agaricus blazei Murrill
Abstract & Commentary
By Donal O'Mathuna, PhD. Dr. O'Mathuna is a lecturer in Health Care Ethics, School of Nursing, Dublin City University, Ireland; he reports no financial relationships relevant to this field of study.
Source: Firenzuoli F, et al. The medicinal mushroom Agaricus blazei Murrill: review of literature and pharmaco-toxicological problems. Evid Based Complement Alternat Med 2008;5:3-15.
Agaricus blazei murrill (abm), popularly known as "Cogumelo do Sol" in Brazil, or "Himematsutake" in Japan, is a mushroom native to Brazil, and widely cultivated in Japan for its medicinal uses, it is now considered one of the most important edible and culinary-medicinal biotechnological species. It was traditionally used to treat many common diseases like atherosclerosis, hepatitis, hyperlipidemia, diabetes, dermatitis, and cancer. In vitro and in vivo ABM has shown immunomodulatory and antimutagenic properties, although the biological pathways and chemical substances involved in its pharmacological activities are still not clear. The polysaccharides phytocomplex is thought to be responsible for its immunostimulant and antitumor properties, probably through an opsonizing biochemical pathway. Clinical studies are positive confirmations, but there are perplexing concerns, especially relative to the content of agaritine. Agaritine is a well-known carcinogenic and toxic substance in animals that must be completely and fully evaluated.
Commentary
The article by Firenzuoli and colleagues provides a thorough review of the scientific and clinical data available about an increasingly popular medicinal mushroom. The mushroom is native to Brazil, where it came to the attention of Japanese researchers in 1960. It has since become one of the most widely used medicinal mushrooms in Asia and South America. It is estimated that about half a million people in Japan have used it for the prevention of cancer, or after removal of a tumor.1 Another survey found that the mushrooms are the most commonly used "health food" by Japanese patients with urological cancer. Its scientific name is Agaricus blazei Murrill, though there is much debate over whether it is the same as Agaricus subrufescens and, thus, ought to be known by that name instead.2 Several common names are used in Brazil, some of which translate as "mushroom of God" or "mushroom of life." In Japan it is called Himematsutake.
ABM is available as a functional food, since the mushroom is edible, and also as a dried extract sold in capsule form. Although traditionally used to treat a variety of conditions like diabetes, atherosclerosis, hepatitis, and heart disease, most of the recent attention has focused on its use in the prevention and treatment of cancer. Its popular usage has led to much research in Japan, which is now being used to market the products in America.
Firenzuoli et al include a botanical section which highlights an important difficulty with the ABM products currently on the market. Japanese researchers have isolated a group of anticancer compounds called beta-glucans. The variety and yield of these is highly dependant on when and how the mushrooms are harvested. The most active beta-glucans are available in more mature mushrooms, which are also more liable to decomposition. For this reason, the species remains difficult and expensive to grow and process, which has led to much variability in the products currently available.
Beta-glucans are a type of polysaccharide known to have anti-cancer activity. They stimulate the body's own defense mechanisms rather than directly killing cancer cells. ABM mushrooms have a very high beta-glucan content, higher than other Japanese medicinal mushrooms like Reishi and Shiitake. Firenzuoli et al's comprehensive review of the literature found numerous laboratory tests of ABM extracts. While some had anticancer activity, others had none, and some promoted the growth of cancer cells. They concluded that with the variety of extracts currently available, "it is difficult to now obtain reliable and definitive data about anticancer activity in vitro."
The review found some animal studies with encouraging results. Most confirmed that ABM extracts work primarily by stimulating animals' immune systems. A few studies also found some evidence of direct tumoricidal activity. One found that human ovarian cancer cells did not spread in mice given an ABM extract, though the same was not found for lung cancer cells.
Surveys of Japanese users of ABM have found it well-tolerated. However, wild mushrooms accumulate heavy metals, which has led to concerns that diets rich in wild mushrooms could inadvertently lead to high levels of environmental toxins. Another concern is that ABM contains agaritine, a known carcinogenic and toxin in animals. Agaritine levels vary between extracts, with one product voluntarily taken off the market in Japan when it was found to have high levels of agaritine. ABM extracts have been found to inhibit liver enzymes that metabolize other drugs, making drug interactions likely. Three cases of liver damage have been reported in patients taking ABM, but it is too early to establish whether ABM caused the damage. More research is urgently needed into this area, especially given the large amounts of extract typically taken by patients (3-5 g/day).
Scientific investigations of ABM extracts show that the mushrooms contain numerous compounds that could be developed into useful agents in preventing and treating cancer. Some of these compounds may be particularly beneficial in combination with other chemotherapy drugs, or as a way to reduce the side-effects of other drugs. However, relatively little research has moved beyond culture plates into animals, and even less into human trials. The few studies available have been surveys of cancer patients' satisfaction with ABM. While the mushrooms have much potential to provide useful compounds at some point in the future, Firenzuoli et al conclude that more research is needed before recommending ABM to prevent or treat cancer. Caution is especially warranted given the potential for drug interactions and other toxic effects from the mushrooms and their extracts.
References
1. Takaku T, et al. Isolation of an antitumor compound from Agaricus blazei Murrill and its mechanism of action. J Nutr. 2001;131:1409-1413.
2. Kerrigan RW. Agaricus subrufescens, a cultivated edible and medicinal mushroom, and its synonyms. Mycologia. 2005;97:12-24.
Agaricus blazei murrill (abm), popularly known as "Cogumelo do Sol" in Brazil, or "Himematsutake" in Japan, is a mushroom native to Brazil, and widely cultivated in Japan for its medicinal uses, it is now considered one of the most important edible and culinary-medicinal biotechnological species.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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