Mushrooms have been used in Oriental medi-cine for over 7000 years. But only recently has the West begun to wake up to the medicinal and healing capabilities of these functional fungi. After several decades of extensive scientific scrutiny, various species show great promise against a raft of diseases.
Potent cancer fighter
A number of mushroom components stimulate the immune system and inhibit tumour growth. In particular, their 'polysaccharides'-long-chain sugar molecules-have been repeat-edly proven to have antitumour and immunostimulant properties.
In the most comprehensive review of the literature, Cancer Research UK confirmed the anticancer activity of polysaccharides from various mush-rooms, including reishi (Ganoderma lucidum), shiitake (Lentinula edodes), maitake (Grifola frondosa) and kawara-take (Coriolus versicolor).
Of these, the shiitake mushroom and its polysaccharide lentinan have been the most extensively researched. Numerous studies have demonstrated lentinan's powerful immune-boosting effects, which enhance the body's natural antitumour capabilities rather than attack tumour cells themselves (Appl Microbiol Biotechnol, 2002; 60: 258-74).
First isolated in 1970, lentinan showed greater antitumour effects than other mushroom polysaccharides and was effective against some, though not all, types of tumours (Int J Cancer, 1974; 12: 259-61). In Japan, lentinan is approved for use as an anticancer drug. It is considered an important adjuvant treatment for several types of tumours, especially stomach and colorectal cancers.
In one study of advanced stomach cancer, chemotherapy patients who received injections of lentinan once or twice a week in addition to the usual drugs lived significantly longer and had a better quality of life compared with patients who received chemotherapy alone (Hepatogastroenterology, 1999; 46: 2662-8). Lentinan also seems to greatly reduce the debilitating side-effects of chemo such as nausea, pain, hair loss and reduced immunity.
However, although the compound given orally can reduce colon cancer in animals (J Altern Complement Med, 2002;
8: 581-9), a US study of more than 60 men with prostate cancer found that six months of treatment with shiitake extract halted the disease in only four of them (Urology, 2002; 60: 640-4).
More promising is the kawaratake mushroom. Coriolus, a long-estab-lished folk medicine for cancers of all kinds, is traditionally taken as a tea. Two extracts-polysaccharide-K (PSK; 'krestin') and polysaccharopeptide (PSP)-both have potent anticancer properties when taken orally. In fact, krestin is rated among the world's best-selling cancer drugs-and among the world's best-selling drugs overall-and has no major side-effects, making it useful for debilitated or elderly patients (Anticancer Res, 2002; 22: 1737-54).
In one randomized, placebo-controlled trial of more than 100 patients after cancer-related surgery, significantly more patients were still alive and disease-free after 10 years with PSK than with a placebo (Cancer Immunol Immunother, 1990; 31: 261-8).
In another Japanese trial of more than 400 patients, again after colo-rectal-cancer surgery, 75 per cent of those given PSK plus chemotherapy were alive after three years, compared with 40 per cent of those given only chemo (Dis Colon Rectum, 1992; 35: 123-30).
In a follow-up study of patients after radiotherapy for lung cancer, nearly 40 per cent of those taking PSK were still alive after five years compared with 16 per cent of those not taking PSK (Anticancer Res, 1993; 13: 1815-20).
PSK can also prolong life in those with cancers of the breast, nasophar-ynx, oesophagus and stomach (Altern Med Rev, 2000; 5: 4-27).
PSP, its sister polysaccharide, has also shown powerful benefits for the immune system, as well as substantially reducing pain and improving quality of life in those with cancers of the stomach, oesophagus, lung, ovary and cervix (Altern Med Rev, 2000; 5: 4-27).
Reishi and maitake mushrooms also have anticancer effects. Reishi appears to stimulate the immune system-in particular, tumour necrosis factor-to attack cancer cells (Int J Cancer, 1997; 70: 699-705). Maitake attacks the cancer cells directly. In one test-tube study, beta-glucan, the polysaccharide from maitake, killed over 95 per cent of prostate-cancer cells (Mol Urol, 2000; 4: 7-13).
Clinical trials are underway in the US and Japan not only with prostate cancer, but also with cancers of the breast, lung, liver and stomach (Smith JE et al. Medicinal Mushrooms and Cancer, Chapter 7. Cancer Research UK; see www.icnet. uk/labs/med_mush/med_mush.html).
According to City of Hope's Beck-man Research Institute in Duarte, California, even eating those white supermarket mushrooms-from baby buttons to large stuffers-can help ward off breast cancer (J Nutr, 2001; 131: 3288-93; Cancer Res, 2006; 66: 12026-34).
Extracts of white button mush-rooms (Agaricus bisporus) can sup-press oestrogen production, which plays a major role in breast cancer. Crimini (including portabella) mush-rooms have similar actions. One active ingredient in these mushrooms is conjugated linoleic acid, a well-known anticancer agent.
Although mushrooms cannot treat breast cancer, say the researchers, eating about 100 g/day of white mush-rooms may act as a preventative in postmenopausal women; non-meno-pausal women can have a lower intake and still benefit.
Mushrooms have shown impressive activity against diabetes. In mice, mai-take significantly reduced blood sugar (Biol Pharm Bull, 1994; 17: 1106-10), and doctors at New York Medical College have found that a daily dose of 1000 mg of maitake in patients with severe type 2 (non-insulin-dependent) diab-etes can permanently normalize blood sugar levels (Diabetic Med, 2001; 18: 1010).
Reishi-known in China as lingzhi, the 'plant of immortality'-can also reduce blood glucose in diabetic patients (Int J Med Mushr, 2005; 7: 111-8). Moreover, reishi can prevent or delay diabetic kidney problems-albeit in mice, so it may not apply to humans (J Asian Nat Prod Res, 2006; 8: 705-11).
Yet another mushroom helpful in diabetes is Agaricus blazei Murill (ABM). In a randomized, double-blind study of 72 patients with type 2 diab-etes, those receiving ABM extract-1500 mg/day for 12 weeks-had an improved insulin resistance compared with those given a placebo (J Altern Complement Med, 2007; 13: 97-102).
The effect was attributed to increas-ed adiponectin, a hormone that regu-lates fat and sugar metabolism.
AIDS and HIV
Mushrooms can even help HIV/AIDS patients to improve their immune function. In a controlled trial of 100 HIV patients, lentinan taken with the drug didanosine (ddI) increased levels of CD4 cells-among the immune system's main defenses-more than with ddI alone (J Med, 1995; 26: 193-207).
What's more, according to its Japanese inventors, a patented beta-glucan extract of maitake known as the 'MD-Fraction' is the most effective of all the known anti-HIV polysaccharides and is as powerful as the drug AZT (Altern Med Rev, 2001; 6: 48-60). In one long-term study, the MD-Fraction was given to 35 HIV-positive patients for 360 days. Although the results were mixed, 85 per cent of the patients reported an increased sense of well-being in terms of symptoms and secondary HIV-related diseases. The MD-Fraction appears to work by direct inhibition of HIV and stimulation of the body's own natural defences against HIV, rendering the patient less vulnerable to disease (Mycoscience, 2000; 41: 293-5).
Coriolus and reishi mushrooms may also have a place in fighting HIV (Life Sci, 1997; 60: PL383-7; Phytochemistry, 1998; 49: 1651-7).
The medicinal properties of mush-rooms are full of possibilities, but the research is still in its early stages. Nevertheless, there are a number of commercially available mushroom products already on the shelves.
Look for liquid products rather than powdered (dried) supplements as, in general, they are thought to be more bioavailable (readily taken up by the body). However, there appears to have been no systematic attempt to evaluate this claim scientifically. Liquid extracts may just be more concentrated than the powdered ones.
There is, however, evidence to suggest that using whole mushrooms or mushroom extracts may be more beneficial than taking its isolated components such as polysaccharides. According to scientists from the University of California, whole mush-rooms contain a number of important active ingredients that may play a synergistic role against disease (Exp Biol Med, 2004; 229: 393-406).
Finally, it's worth remembering that medicinal and culinary mushrooms are often one and the same, so many of
the benefits of mushrooms can be had simply by making them a routine part of your diet. Recent research by the
US Department of Agriculture has discovered that most nutrients in raw mushrooms are fully retained when cooked, while others are retained at levels of between 80 and 95 per cent (www.ars.usda.gov/is/pr/2006/060818.htm).
- A polysaccharide from shiitake has demonstrated benefit in chronic hepatitis sufferers. LEM (Lentinula edodes mycelia) protects the liver, improves liver function and helps produce antibodies to hepatitis B (J Beijing Med University, 1987; 19: 93-5; Gasteroenterol Jpn, 1987; 22: 459-64; Kantansui, 1987; 14: 327-35).
- Because maitake is rich in fibre, yet low in calories and fat, it is a potential weight-loss aid. In a study of more than 30 overweight patients, those who took maitake tablets (equal to 200 g of fresh mushrooms) daily for two months lost weight, despite making no other changes to their usual diets (Altern Med Rev, 2001; 6: 48-60).
- Japanese researchers have found that eating raw mushrooms can eliminate bad breath. Button, field and birch bolete mushrooms were among those with a high ability to 'capture' methyl mercaptan, the main chemical responsible for halitosis (J Agric Food Chem, 2001; 49: 5509-14).
- In 2005, a Norwegian study concluded that an extract of Agaricus blazei Murill, an edible mushroom from Brazil, can both treat and prevent bacterial infections such as otitis media, bronchitis, pneumonia and meningitis (Scand J Immunol, 2005; 62: 393-8)
- Fungal materials may make good artificial skin and wound covers. The idea came from similar products based on crustacean shells and the fact that fungal cell walls also contain chitin and/or chitosan. Indeed, Sacchachitin, prepared from the waste residues of Ganoderma tsugae (hemlock varnish shelf) fruiting bodies, can enhance skin wound-healing in both animals and humans (J Biomed Mater Res A, 2005; 72: 220-7).