Medicinal Mushrooms:Good Source of Dietary Supplements

Medicinal Mushrooms, Good Source of Dietary Supplements
Medicinal Mushrooms, Good Source of Dietary Supplements

It is believed that human beings have constantly searched for new substances that can imporve biological functions and make people fitter and healthier. Recently, Western society has turned to plants, herbs and foods as sources of these enhancers. These products have been called, variously: vitamins, dietary supplements, functional foods, phytochemicals, nutraceuticals (Zeisel 1999) and nutriceuticals (Chang and Buswell 1996). They are designed to supplement the human diet, not to be used as a regular food, by increasing the intake of bioactive compounds for the enhancement of health and fitness. The industries involved in providing these substances are expanding in the United States. In 1990, US diet-supplement sales were valued at US$3.3 billion; in 1992, US$3.7 billion; in 1994, US$5.0 billion; in 1996, US$6.5 billion; in 1998, US$12.0 billion; and in the year 2000 it is estimated to be US$ 14.0 billion (Zeisel 1999). It is expected that these dietary supplement products will soon be recognised and marketed in Europe and Eastern Asia.

Present-day high-pressure work-demands result in great stress to the human body, which causes a weakening of the human immune system. This has developed as a consequence of lower natural body resistance resulting in an increased proneness to disease. There is some evidence that beneficial treatment of these diseases can be obtained by consumption of mushrooms as a functional food or through the use of extracted biologically active compounds as a dietary supplement. Differing from most pharmaceuticals, the biologically active compounds that are extraced from mushrooms (nutriceuticals) have extraordinarily low toxicity, even at high doses. Long viewed as tonics, it is now known that they can profoundly improve the quality of human health.

Medicinal mushrooms have been used as a dietary supplement or medicinal food in China for over 2,000 years. In the late 1980s, their extractable ingredients received great attention as products for improving biological function, thus making people fitter and healthier. In some cases, these dietary supplements were used in the prevention and treatment of various human diseases. For example, Francia et al. (1999) listed six groups,

(1) six species which reduce the total cholesterol level, Auricularia auricula-judae, Cordyceps sinensis, Ganoderma lucidum, Grifola frondosa,Pleurotus ostreatus, and Tremella fuciformis;
(2) two species which reduce the “bad cholesterol – the low-density lipoprotein (LDL) level”, Auricularia auricula-judae and Tremella fuciformis;
(3) three species which reduce the triglyceride level, Cordyceps sinensis, Grifola frondosa, and Lentinua edodes;
(4) six species which reduce platelet binding (in vitro), Auricularia auricula-judae, Calyptella sp., Ganoderma lucidum, Kuehneromyces sp.,Neolentinus adhaerens and Panus sp.;
(5) three species which may reduce the arterial pressure, Ganoderma lucidum, Grifola frondosa and Tricholoma mongolicum and
(6) six species which may decrease glycemia, Agaricus bisporus, Agrocybe aegerita, Cordyceps sinensis, Tremella aurantia, Grifola frondosa andCoprinus comatus.

There is intense industrial interest currently in a novel class of compounds extractable either from the mycelium or fruiting body of mushrooms. These compounds called “mushroom nutriceuticals” (Chang and Buswell, 1996), exhibit either medicinal and/or tonic qualities and have immense potential as dietary supplements for use in the prevention and treatment of various human diseases. In 1994, they constituted a US$3.6 billion industry (Chang, 1996). The application of modern analytical techniques has revealed many medicinal mushrooms to contain numerous bioactive compounds including polysaccharides (Lentinan from Lentinula edodes), immunomodulatory proteins (lZ-8 from Ganoderma lucidum; Fip-fve fromFlammulina velutipes, Flip-vvo from Volvariella volvacea) and protein-bound polysaccharide (PSK and PSP from Coriolus versicolor; PSPC fromTricholoma sp). Many of these compounds have anti-cancer and anti-tumour properties that appear to be based on an enhancement of the host immune system rather than on a direct cytocidal effect (Chang and Buswell, 1999).

Although there are no published figures related to the total world market value of medicinal mushrooms, the market value for G. lucidum – a mushrooming medicinal mushroom in 1995 was estimated to be about US$1,628.4 million (Chang and Buswell, 1999). The market values of the mushroom products were estimated to be US$350 million in China, US$600 million in Korea, US$300 million in Japan, US$215 million in Taiwan, US$91.2 million in Malaysia, US$60 million in Hong Kong, US$2.2 million in Singapore and US$10 million in other countries. Furthermore, these products are without troublsome side effects that frequently accompany the synthetic drugs used for these purposes. Exactly how these products work is still a matter of conjecture, but numerious human clinical trails have shown that they are effective. People unfamiliar with the field may say that if the products from these medicinal mushrooms have such beneficial effects, why don’t chemists isolate the active components so that they can be marketed as drugs? The answer is that there may be no single active component, instead, there are many of them. They may be similar or quite different chemically, but they all contribute to the beneficial overall effect of the mushroom.

The use of standardised extracts of the mycelium or fruiting bodies of the mushroom is what distinguishes nutriceuticals (Mushroom medicines) from both the use of whole mushrooms (as food) and of single chemicals (as a drug). Whole mushrooms, like all other natural materials, vary considerably in their quality, and their beneficial action may be unreliable. Single chemicals often provide such intense responses that they are accompanied by very unpleasant side effects. Nutriceuticals, which are extracted products, occupy a middle ground between these extremes and have proven to be very useful. However, to obtain a good quality and trustworthy product is of paramount importance.

Mushroom nutriceuticals are likely to be of increasing interest throughout the world. They represent both challenges and opportunities. Who knows? Perhaps a whole new industry, or even industuries, will arise having greater economic value than those currently producing mushrooms for food.

By Dr. S. T. Chang, From  
Emeritus Professor of Biology and Director of Centre for International Services to Mushroom Biotechnology,The Chinese University of Hong Kong, Shatin, N. T. Hong Kong.