From the frying pan into the clinic

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From the frying pan into the clinic

There’s more to mushrooms than meets the eye. Rather than just being a tasty addition to your dinner, they’re becoming increasingly important in medical treatment.

Fungi are everywhere. From dermatophytes that cause an athlete’s foot infection to green growths on stale bread, from black mould at the corners of damp windows to the 1.5kg white truffle (Tuber magnatum Pico) that sold for £165,000 at a 2007 charity auction. Now increasing evidence suggests that fungi in general, and mushrooms in particular, may offer new treatments for cancer, antibiotic-resistant ‘superbugs’ and some other serious medical problems.

Fungi have been mainstays of folk medicine worldwide for thousands of years, particularly in the Orient, but also in Europe. Until the middle of the last century, for example, people in rural communities in the UK used dried Puff Balls (Calvatia gigantea) to stop bleeding and aid wound healing. The stinkhorn (Phallus impudicus) lives up to its name: homeowners sometimes mistake the pungent odour of a colony of stinkhorns for blocked drains.

Yet traditional healers in central Europe used ointments and powders made from stinkhorns to treat gout, rheumatism and epilepsy. They even used the stinkhorn as a love potion and aphrodisiac, although that had more to do with the mushroom’s shape than its perfume.

Animals, plants and bacteria each belong to different kingdoms and we now know that fungi belong to their own biological kingdom. There are different types of fungi. Yeast is an example of a single-celled fungus while mould, either on bread or windows, consists of a network of long, fine, intertwined, branching threads called a mycelium. Some fungi produce visible fruiting bodies from their mycelium – toadstools and mushrooms – and these release spores, the fungal equivalent of seeds.

Many medical traditions around fungi may have a kernel of truth. During the eighteenth century, for instance, doctors and midwives across Europe used the ergot fungus, which grows on rye and other cereals, to stop bleeding after birth and to induce abortions. Midwives and doctors still use a synthetic version of the fungi’s active ingredient, known as ergometrine, if a woman suffers heavy bleeding after birth (post-partum haemorrhage), notes Nicky Clark, head of the Midwifery and Child Health Department at the University of Hull.

“Oxytocin is a natural hormone, but is now synthesised and is known as Syntocinon,” Nicky explains. “Syntocinon is used to induce or speed up labour contractions. Syntocinon is also combined with ergometrine to form Syntometrine, which is administered routinely to nearly all women immediately after the baby is born to aid delivery of the placenta and to control post-partum haemorrhage.”

New cancer treatments

Mushrooms are also attracting considerable interest as a source of new drugs for cancer and bacterial infections. Half of the people reading this article will develop cancer, and despite remarkable advances in screening, diagnosis and treatment, one person dies from cancer every three minutes. So researchers are hunting innovative cancer treatments, as well as supportive drugs that help people better tolerate chemo- or radiotherapy.

Several strands of evidence suggest that mushrooms might provide a rich source of new cancer treatments. For instance, women from China who eat a traditional diet are four to five times less likely to develop breast cancer than those from industrialised countries. Mushrooms, a staple of Chinese cuisine, might be partly responsible.

A study in the International Journal of Cancer reported that women in China who ate at least 10 grams of fresh mushrooms a day were 64 per cent less likely to develop breast cancer than those who didn’t eat mushrooms. Women who ate at least four grams a day of dried mushrooms were 47 per cent less likely to develop breast cancer.

Indeed, numerous mushrooms seem to have anti-cancer actions, at least in the laboratory. Writing in the Biomedical Journal, Dr Russell Paterson and Nelson Lima noted that 12 different species of mushrooms produce polysaccharides (a type of sugar) with potential anticancer actions. Dr Paterson, a researcher at the Centre for Biological Engineering, University of Minho, Portugal, has studied fungi for more than 40 years and commented that polysaccharide K (also called krestin) is currently the most promising anticancer chemical produced by mushrooms.

Polysaccharide K comes from one the most common mushrooms, the Turkey Tail fungus (Trametes versicolor; also called Coriolus versicolor), which you can see in woods across the UK. Polysaccharide K is already widely used in Japan and some other Asian countries alongside conventional cancer drugs and radiotherapy to bolster the immune system’s ability to attack malignancy.

A recent paper published in the Integrative Cancer Therapies journal, for example, reviewed 28 studies assessing polysaccharide K in lung cancer, one of the deadliest malignancies. In experimental studies, polysaccharide K boosted the immune system, directly inhibited lung cancer cells, reduced tumour growth and prevented the spread of cancerous cells (metastasis).

In humans, polysaccharide K prolonged survival, improved general wellbeing (or so-called performance status), body weight, fatigue and loss of appetite. Indeed, Paterson and Lima point out, numerous studies in animals and humans suggest that a variety of polysaccharides from mushrooms reduce the side effects of chemo- and radiotherapy.

“The anti-cancer uses of mushrooms are important and some Asian companies already produce approved preparations that are used alongside conventional treatments in mainstream clinics,” Dr Paterson says. “Unfortunately, these mushroom preparations tend not to be used in the West. Gaining wider acceptance means developing methods for mass production of the pure bioactive compounds, especially as they can be difficult to make synthetically. Overcoming these issues could encourage drug companies to invest more in these promising compounds.”

Overcoming bacterial resistance

Mushrooms are also a promising source of new antibiotics to tackle the rising tide of resistance. Penicillin, of course, was originally discovered in a blue-green mould, and the Shiitake mushroom (Lentinus edodes) – cultivated in Japan for more than 2,000 years on logs of Shii, hornbeam or other trees – is one of the best studied mushroom sources of new antibiotics. One study reported that extracts of Shiitake mushroom were active against 85 per cent of the 29 bacterial and 10 fungal pathogens tested. Shiitake’s activity was comparable to ciprofloxacin, a conventional antibiotic. Researchers are trying to identify the active compounds – mushrooms produce a complex cocktail of chemicals – to develop new antibacterials.

However, Dr Paterson worries that pharmaceutical companies may be reluctant to follow these promising leads. “Resistance by bacteria to conventional antibiotics is well known and increasingly compounds of last resort are required,” he says. “These last resort compounds have a smaller market than conventional antibiotics as, with a few exceptions, they are used only when there is no alternative. So, a pharmaceutical company has little incentive to develop new antibiotics when they will be used only as a last resort. In my view, governments need to fund this type of work in a less profit-oriented environment.”

Despite promising results in cancer, antibiotic resistance and other conditions, we’ve only scratched the surface of the medical potential of mushrooms. According to Dr Paterson, only 10 to 15 per cent of the 150,000 species of mushroom have been studied scientifically. “Over the next 10 years or so, I expect interest in the medical properties of mushrooms to increase,” he says. “But economic issues mean that the development of preparations will be slow. In some cases – such as bacterial resistance – we need to overcome these issues urgently.”

Indeed, Chinese pharmacopoeias include more than 100 species of mushrooms for a variety of ailments and, Dr Paterson notes, major Asian companies now produce several mushroomderived medical products. Yet in the West, medicinal mushrooms remain more of a curiosity than a medical mainstay. Perhaps it’s time we performed more scientific clinical trials of mushroom products and caught up.

One study reported that extracts of Shiitake mushroom were active against 85 per cent of the 29 bacterial and 10 fungal pathogens tested

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