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A number of edible fungi have acquired a reputation for conferring health benefits. Shiitake, Reishi and Maitake mushrooms, for example, have a long history of use in Japanese and Chinese medicine as treatments for infections and cancer; other less-well known but equally exotic fungi have an established place in Ayurvedic and Aboriginal medicine, with similar indications.

Our medical profession has little time for this sort of mystical nonsense, and in the UK the medicinal fungi were the exclusive preserve of herbalists and a few health nuts until, in the mid-70’s, the multinationals brought them to our supermarket shelves and the weekly magazines started writing enthusiastic (if uncritical) articles about their amazing health benefits. Our homegrown white button mushrooms just couldn’t compete in the alternative health stakes – although they have always remained, in my view, an essential component in the Great British Breakfast.

New research, however, is forcing the medical profession to re-evaluate the role of the mushroom. Moreover, it has revealed that the conventional division between medicinal and edible fungi is a meaningless one. All fungal species, it now seems, have the ability to get the immune system going – and the little white button mushroom, just like its Oriental cousins, has now been revealed as a tried and tested immuno-stimulant. (This is significant because the white button mushroom is far more widely consumed than any other type of mushroom, accounting for around 90% of our total fungal intake.)

A group of researchers from Tufts University, working in collaboration with the Chinese National Institute of Communicable Disease Control and Prevention, has just published a very interesting paper in which they report that white button mushrooms activate the innate immune system (Wu et al ’07); an effect known to improve resistance to bacterial and viral infection, and to play an important role in the prevention of cancer. It seems that the Chinese and Indian healers who used fungi for these very purposes were right on the button!

The research team looked at the effect of feeding mice a diet containing white button mushroom powder for 10 weeks, on markers of innate and acquired immune system health. (Just to remind you - the innate immune system is the non-specific part of the immune system that is always ‘on’, and the acquired immune system is the specific part that has a memory. Although the acquired part is involved in immunisation, it is the innate part that is most important in protecting us most of the time).

Supplementation with mushroom powder boosted the activity of natural killer (NK) cell activity, and production of tumour necrosis factor- (TNF) and interleukin-2 (IL-2). NK cells are a vital part of the immune system. Their main role is to kill virally infected cells, and cancer cells. Depressed NK activity is associated with increased cancer incidence as well as an increased susceptibility to colds and infections.

The researchers’ concluded: "These results suggest that increased intake of white button mushrooms may promote innate immunity against tumours and viruses through the enhancement of NK activity.”

Their conclusion, it seems to me, could well have been more assertive. Many other research groups have already shown that fungal extracts enhance innate immune function (Lin et al ’06), leading to improved resistance to infection in animals (Ritz et al ’06), and enhanced cancer cell killing in vitro (Guo et al ’07, Xie et al ’06). Others again have shown that these effects translate directly into clinical benefits, with a series of Japanese trials showing that fungal extracts improve quality of life and survival in cancer patients when used either as sole agents (Nakano et al ’99, Nimura et al ’03, Nagahashi et al ’04), or in conjunction with mono-clonal antibodies (Kawaoka et al ’05).

There is no mystery to any of this. All fungi contain molecules called 1-3, 1-6 beta glucans in their cell walls; and it is well known that these compounds activate the innate immune system. Similar molecules occur in barley, dates and Echinacea – and yes, these too have been shown to have immuno-stimulant and tumour killing properties (Modak et al ’05, Ishurd et al ’04).

These and other research findings have stimulated the supplements industry to produce a range of beta glucan supplements extracted from a variety of sources `-although I have not yet seen any barley or date extracts on the market. So which ones should the consumer go for?

The source itself doesn’t matter; what is important is the structure and size of the 1-3, 1-6 beta glucan molecules it provides, which must fit beta glucan receptors on specific immune cells if they are to elicit an innate immune system response (Czop & Austen ’85). And from this perspective, the answer is clear; 1-3, 1-6 beta glucans derived from baker’s yeast provide the best fit and are the most consistent and most effective immuno-priming compounds, out-performing mushroom and Echinacea extracts by a long way (Biothera ’06).

• Biothera ’06. Source: James Graham Brown Cancer Centre, University of Louisville 2006
  
  
• Czop JK, Austen KF ‘85: A b-glucan inhibitable receptor on human monocytes: its identity with the phagocytic receptor for particulate activators of the alternative complement pathway. J Immunol 1985; 134: 2588-2593.
  
  
• Guo J, Zhu T, Collins L, Xiao ZX, Kim SH, Chen CY. Modulation of lung cancer growth arrest and apoptosis by Phellinus Linteus. Mol Carcinog. 2007, 46(2):144-54.
  
  
• Ishurd O, Zgheel F, Kermagi A, Flefla M, Elmabruk M. Antitumor activity of beta-D-glucan from Libyan dates. J Med Food. 2004 Summer;7(2):252-5.
  
  
• Lin YL, Lee SS, Hou SM, Chiang BL. Polysaccharide purified from Ganoderma lucidum induces gene expression changes in human dendritic cells and promotes T helper 1 immune response in BALB/c mice. Mol Pharmacol. 2006;70(2):637-44.
  
  
• Kawaoka T, Yoshino S, Kondo H, Yamamoto K, Hazama S, Oka M. Clinical evaluation of intrapleural or peritoneal repetitive administration of Lentinan and OK-432 for malignant effusion Gan To Kagaku Ryoho. 2005 Oct;32(11):1565-7. Japanese
  
  
• Modak S, Koehne G, Vickers A, O'Reilly RJ, Cheung NK. Rituximab therapy of lymphoma is enhanced by orally administered (1-->3),(1-->4)-D-beta-glucan. Leuk Res. 2005 Jun;29(6):679-83.
  
  
• Nakano H, Namatame K, Nemoto H, Motohashi H, Nishiyama K, Kumada K.
  A multi-institutional prospective study of lentinan in advanced gastric cancer patients with unresectable and recurrent diseases: effect on prolongation of survival and improvement of quality of life. Kanagawa Lentinan Research Group. Hepatogastroenterology. 1999 Jul-Aug;46(28):2662-8.
  
  
• Nimura H, Mitsumori N, Tsukagoshi S, Nakajima M, Atomi Y, Suzuki S, Kusano M, Yoshiyuki T, Tokunaga A. Pilot study of TS-1 combined with lentinan in patients with unresectable or recurrent advanced gastric cancer Gan To Kagaku Ryoho. 2003 Sep;30(9):1289-96. Japanese.
  
  
• Ritz BW, Nogusa S, Ackerman EA, Gardner EM. Supplementation with active hexose correlated compound increases the innate immune response of young mice to primary influenza infection. J Nutr. 2006, 136(11):2868-73.
  
  
• Wu D, Pae M, Ren Z, Guo Z, Smith D, Meydani SN. "Dietary Supplementation with White Button Mushroom Enhances Natural Killer Cell Activity in C57BL/6 Mice". J Nutrition 2007, 137:1472-1477
  
  
• Xie JT, Wang CZ, Wicks S, Yin JJ, Kong J, Li J, Li YC, Yuan CS. Ganoderma lucidum extract inhibits proliferation of SW 480 human colorectal cancer cells.
  Exp Oncol. 2006;28(1):25-9.
  

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