Rare cases of mushroom toxicity (five per 100,000 people),1 incidences of metal contamination and cultural disparities regarding the consumption of fungi has the industry still waiting for the mushroom moment.
Over the past few years some well-controlled clinical trials have been completed, which may be the turnaround needed to drive the market forward. The following is a brief overview of these studies - including some unpublished data I feel will turn the public on to mushrooms like never before.
Mushrooms for increased energy
Energy-boosting supplements could be the strongest-growing category in the dietary supplements industry. Mushrooms seem to be carving out a niche for energy-hungry consumers. In a recent publication, the effect of agaricus mushrooms on the energy metabolism and activities of enzymes related to energy metabolism was measured in calves.2 Animals were supplemented with 60g/day Agaricus blazei murill extract for four weeks. Activities of energy-producing enzymes (malate dehydrogenase and aspartate aminotransferase) were significantly higher in those supplemented with A. blazei than those in the control group without A. blazei.2 The extract was effective in activation of enzymes related to energy metabolism in peripheral leukocytes of calves. This provides the beginnings of evidence for mushrooms' application as an effective energy enhancer.
Cancer and the PL mushroom
It has been demonstrated that the Phellinus linteus (PL) mushroom extract, known as 'sang-hwang' in Korean, 'mesimakobu' in Japanese and 'song gen' in Chinese, possesses antitumour activity.
The anticancer drug doxorubicin (Dox) has been shown to induce apoptosis (programmed cell death) in cancer cells. However, higher doses can damage healthy cells. In a study published in the British Journal of Cancer, the effect of the PL mushroom on Dox-induced apoptosis was investigated in prostate cancer cells.3 Researchers showed that PL or Dox, at relatively low doses, could not kill these cells. However, combination treatment at low doses of PL and Dox results in a synergistic effect and brought about death in prostate cells.
These findings indicate that PL has a synergistic effect with Dox to activate a beneficial decline in prostate cancer cells.3 Not only did these researchers find that the combination was just as effective in killing cancerous cells as larger doses of the drug alone, it did so without harming healthy cells.3
Mushrooms and anti-angiogenesis
Angiogenesis is the growth of new blood vessels and is an important process occurring in the human body in both healthy and disease states (cancer, diabetic blindness, age-related macular degeneration). In disease conditions such as cancer, the new vessels allow tumour cells to escape into the circulation and metastasise in other organs. Excessive angiogenesis occurs when diseased cells produce abnormal amounts of angiogenic growth factors, overwhelming the effects of natural angiogenic inhibitors. Anti-angiogenic therapies are aimed at halting new blood-vessel growth and are being developed to treat these conditions.
Researchers from the Department of Medicine, Taiwan, extracted polysaccharides from medicinal fungi, including Antrodia cinnamomea, Antrodia malicola, Antrodia xantha, Antrodiella liebmannii, Agaricus murrill and Rigidoporus ulmarius.4 Results showed that polysaccharides isolated from A. xantha and R. ulmarius provide greater anti-angiogenesis than those from commercialised Brazilian mushroom (A. murrill) and A. cinnamomea.4 These studies provide a basis for the potential development of these polysaccharides for anti-angiogenesis usage. Further work on humans and specific disease states linked to angiogenesis is needed to directly link mushroom medicine to human health.
Excessive allergic reactions (anaphylaxis) are commonly caused by insect bites/stings, horse serum (used in some vaccines), and food and drug allergies. Anaphylactic reactions can be mild to life threatening and the annual incidence of anaphylactic reactions is about 30 per 100,000 persons, according to the Food Allergy & Anaphylaxis Network in 2006.
The Agaricus blazei is a medicinal mushroom native to Brazil with antitumour and immunoactive properties that have led to its promotion as an effective health food in many countries. An investigation into the effect of Agaricus blazei water extract (ABWE) on mast cell-mediated anaphylaxislike reactions aimed to clarify its immunomodulatory actions.5
This recent study using ABWE assessed systemic inhibition of anaphylaxislike reaction, ear-swelling response and mast-cell activation in response to compound 48/80 (a histamine-depleting agent). ABWE dose-dependently inhibited compound 48/80-induced systemic anaphylaxislike reaction, and ear-swelling reaction in mice. Moreover, pretreatment with ABWE reduced compound 48/80-induced calcium uptake into rat peritoneal mast cells.5
These results propose that ABWE may be beneficial in treating mast cell-mediated anaphylactic reactions and may have applications in reducing the severity of anaphylactic reaction to food and other sources that induce anaphylaxis.
Shrinking waistlines with mushrooms?
Mushrooms are about to get the push they need, mediawise. A recent nutrition research quarterly update (June 2006) by the Mushroom Council (Dublin, CA) on up-and-coming funded research has given the first insight into the great work on mushrooms and weight control to be released in early 2007.
Dr Shiuan Chen from the Department of Surgical Research, Duarte, CA, has submitted a manuscript for publication on his mushroom research titled "Does substitution of meat products with white button mushrooms have potential for weight reduction?" A preliminary analysis of the dietary records of a few first participants to complete the trial found that the potential calorie savings on the mushroom test meal days vs the meat meal days was 320-345 calories. The percent compensation eating more food outside the substituted meals to make up for the "lost" calories was on average so far about 20 percent. It is too early in the data analysis to determine if these results will hold up as the study progresses and is completed.
An additional finding is that there is, as yet, no significant difference in the palatability ratings between the mushroom and meat meals. Participants liked the meals substituted with mushrooms as much as the original meat versions. There was a trend toward reduced body weight during the week participants were on the mushroom test meals compared to the week they were on the meat test meals. The nutritional impact of the mushroom test meals compared to the meat test meals will be evaluated.
A report on this research includes preliminary analyses of data regarding blood-pressure changes during the one-month feeding periods and appetite responses to the test meals at the end of each dietary trial. At the end of each one-month feeding period, standardised isocaloric meals representing typical foods consumed during the respective trials were fed to fasted participants. Subjects marked a visual analog scale to determine their subjective ratings of hunger immediately before; after one hour; two hours; three hours and four hours after the meal. The responses in appetite were similar during each trial, despite subjects choosing to take in less energy during consumption of the one-month plant/mushroom-based diet.
This may suggest the analogue scale is not a sensitive-enough measure to pick up changes in hunger in this study design. However, results also showed a significant blood pressure-lowering effect as well as total caloric intake. Taken together, these results suggest that a low-carbohydrate diet rich in mushrooms and plant foods is at least as satiating as a low-carbohydrate, animal-based diet or a lower-fat diet. These biochemical mechanisms for the loss of weight in these mushroom-feeding studies have not been made clear, although initial works suggests it is linked to appetite.
Future mushroom growth
Only a handful of mushrooms of the plethora of those in existence have reached prominence in the supplements channel. The most common of these include reishi (Ganoderma lucidum), shiitake (Lentinula edodes), and maitake (Grifola frondosa), which have gained greater public profile due to both the uniqueness of their chemical make-up and the number of credible peer-reviewed publications. Over the past five years we have seen cited growth of peer-reviewed studies increase by 58 percent.5 As such, this rapid increase in our understanding should bolster public trust and confidence in the special properties mushrooms deliver.
1. Goldfrank L: Mushrooms: toxic and hallucinogenic. In: Goldfrank's Toxicologic Emergencies. 6th ed. New York: McGraw-Hill;1998:1207-19.
2. Kimura N, et al. Effect of supplementation of Agaricus mushroom meal extracts on enzyme activities. Res Vet Sci 2006 (In press).
3. L Collins, et al. Phellinus linteus sensitises apoptosis induced by doxorubicin in prostate cancer. Br J Cancer 2006 (In press).
4. Chen SC, et al. Anti-angiogenic activities of polysaccharides isolated from medicinal fungi. FEMS Microbiol Lett 2005;249(2):247-54.
5. Choi YH, et al. Inhibitory effects of Agaricus blazei on mast cell-mediated anaphylaxislike reactions. Biol Pharm Bull 2006;29(7):1366-71.
Mark J. Tallon, Ph.D., is chief science officer of OxygeniX, a London-based consultancy firm specialising in claims substantiation, product development and technical writing. Tallon is also co-founder of Cr-Technologies, a raw ingredients supplier.