Functional funghi: can medicinal mushrooms really improve people’s health?
Veteran broadcaster Sheila Dillon, who was diagnosed with bone marrow cancer in 2011, shared personal information during the presentation of a recent episode of BBC Radio 4 The Food Program. She started taking mushroom supplements after discovering that patients in Japan were being given them to help combat the effects of radiotherapy and chemotherapy, and that, she told listeners, there was “a lot of evidence” that they were doing so. The last time she saw her oncologist, he told her she was “in danger of becoming a superresponder.”
Dillon said she did not know if there was a link between the supplements and her successful treatment. Nevertheless, she is far from the only one open to the idea that fungi have much greater potential to treat health problems than mainstream Western medicine recognizes. One market research company estimates the global market for functional mushrooms will grow from $8 billion in 2020 to $19.3 billion in 2030. Retail chain Holland & Barrett has 17 different fungal supplement products in stock. “In the last two months we have seen a 70% increase in the amount of mushroom products purchased,” says Rachel Chatterton, the company’s head of nutrition, “and we don’t expect the ‘shroom boom’ to slow mushroom growth. shortly.”
Dozens of claims are being made for medicinal mushroom products. The Bristol Fungarium, for example, sells extracts of fungi that are said to relieve anxiety, prevent wrinkles, stabilize blood pressure and relieve hot flashes. From heart health and type 2 diabetes to allergies and cancer, the list of ailments that mushrooms are said to alleviate is long. But are these claims supported by scientific evidence? Or are medicinal mushrooms just the latest fad?
In a former granary on a hill at the end of a country lane in north Somerset, groups of bulbous, cream-coloured young reishi heads rise up on dark red stems, next to rows of giant cauliflower-like lion’s manes protruding from metal plank units. This is the growing room of Bristol Fungarium. In addition, seven employees are hard at work converting fungi into tinctures and packaging them to fulfill orders.
Outside, builders are building a second grow room so the company can double its production. According to Tom Baxter, who founded the company in 2019, turnover last year was around £1.4 million. He expects this to double in the next twelve months.
About half of Bristol Fungarium’s revenue comes from lion’s mane, which, according to a company brochure, benefits patients with mild dementia, has potential in alleviating inflammatory bowel disease (IBD) and “said” to help manage attention deficit hyperactivity disorder. symptoms. However, evidence supporting these claims from human trials is scarce, although extracts from lion’s mane have been shown stimulates the growth of nerve cells in petri dishes and rodents.
“The human body is a galaxy of trillions of cells that interact with each other and with microbes in our microbiome,” says Prof. Nicholas Money, a mycologist at Miami University in Ohio, who published a review about medicinal mushrooms in 2016. “Preliminary cell and animal studies are an interesting starting point, but extrapolating the effects observed in cultured human cells to the treatment of serious conditions is beyond absurd.”
Baxter acknowledges that many of the claims about medicinal mushrooms are based on extrapolation from cell cultures. However, he does highlight two clinical studies involving lion’s mane: one published in 2009which showed that mushroom extracts improved cognitive test scores in older adults with mild cognitive impairment, and another suggested benefits for people with mild Alzheimer’s disease. In the first trial, only fifteen participants took the supplements and in the second study only twenty. Both also involved researchers working for companies that sell mushroom supplements.
Many health claims have been made for reishi, more than 2000 years old, including that it may strengthen the immune system and gut health, relieve fatigue and improve sleep. Some researchers also say that cell culture and animal studies suggest this is possible promoting anti-cancer activity in immune cells and suppress the growth of cancer cells. “Reishi can activate the body’s natural killer cells, which can target cancer cells and increase apoptosis, or programmed cell death, in cancer cells,” says Giuseppe Venturella, a botanist and mycologist at the University of Palermo in Italy.
Although most research on the fungus has been in cell cultures, one review identified 26 human trials of reishi, including some that found benefits for patients with high blood pressure, type 2 diabetes, heart disease, hepatitis B and cancer. The author emphasized that these findings were often undermined by participants knowing they were receiving the treatment, small sample sizes, and a lack of confirmatory follow-up work.
Turkey tail extracts have been used as a mainstream cancer treatment since the 1970s in Japan and the 1980s in China. “Turkey tail is an immune system regulator,” says Baxter. “It’s very good for lung cancer and many different cancers.”
A group led by Dr Karen Pilkington, a research evaluation expert at the University of Portsmouth, reviewed seven randomized controlled trials to investigate whether PSK (polysaccharide-K), an extract from turkey tail, reduced the side effects of radiotherapy or chemotherapy in colorectal cancer patients. The group found that the small number of study participants, the lack of placebo control groups, and the possibility that patients would report side effects differently because they knew they were taking PSK made any benefits unclear.
Chaga, which grows on birch trees and resembles burned charcoal, prevents wrinkles, helps ward off IBD and fights bacterial and viral infections, according to some who sell it. Cordyceps militaristhe ‘zombie fungus’ that inspired the HBO series The last of usIt is reported to improve exercise performance, act as an antidepressant and increase female libido. However, in none of these cases are there any such claims supported by well-designed clinical trials.
According to UK law, food labeling “cannot attribute to any food the property of preventing, treating or curing any disease in human beings”. Such claims are subject to medicines regulations and require marketing authorization from the Medicines and Healthcare Products Regulatory Agency (MHRA). A spokesperson for the MHRA said it had received no marketing requests for products containing lion’s mane, turkey tail, reishi, cordyceps, chaga or shiitake, and that a number of retailers had been warned about making health claims on mushroom products and using the term. “medicinal mushrooms”.
While medications are based on specific purified compounds that have been extensively tested for safety and efficacy, medicinal mushroom supplements can contain hundreds of different chemicals. The levels of active compounds on which the health effects may be based may also vary depending on a number of factors, including age of cultivation, what the mushroom is grown in and whether the extracts come from the fruiting bodies of mushrooms or from their root-like mycelia . . It is also difficult to know what doses are in many mushroom-based products. Tests have shown that sometimes the species of mold is advertised on labels are not even present in the products.
It appears that the vast majority of mushroom health claims are not supported by good quality human trials. However, even skeptics recognize that the absence of evidence is not evidence of absence. Many drugs derived from fungi – including the antibiotics penicillin and cephalosporins and the cholesterol-lowering lovastatin – are already in use. Advances in genome sequencing and techniques for mining genetic information have led to hopes that more of the vast array of compounds that fungi produce can be isolated, purified and used in specific doses to treat human disease .
Money says some of the claims currently being made about medicinal mushrooms are “without scientific basis and amount to little more than snake oil.” But “fungi have rich chemical relationships with other organisms in their environment, and I am sure they contain many more useful compounds,” adds Money, whose book Fungi, mushrooms and medicines will be released in March. “We need to see the use of advanced scientific methods to identify those that are truly beneficial for alleviating or treating human disease.”