Unfortunately, not all mushrooms are beneficial. Of the nearly 100,000 known species, medical mycology identifies about 200 that can cause dangerous, hard-to-treat diseases in humans. Some of these fungi are parasites of tissues and organs and establish themselves in bodies weakened by various factors. Others act as allergens when people come into contact with their spores or metabolic byproducts. Some species can also cause poisoning.
Parasitic fungi can damage organs and tissues such as the eyes, skin, hair, and the mucous membranes of the lungs. The ubiquitous Candida species, which occur on plants, in milk and other foods, and in the human mouth and gastrointestinal tract, can cause systemic infections when the body is weakened—often after prolonged antibiotic use. To prevent such overgrowth, clinicians sometimes give antifungal drugs alongside antibiotics.
Infections and poisonings can also happen when people eat moldy food or food contaminated with toxic fungi. These poisonings most often come from contaminated grains, rice, peanuts, and oilseeds. And who hasn’t heard of the terrifying poisonings caused not by microscopic fungi but by the infamous death cap mushroom? Its toxin is comparable in potency to snake venom. Other poisonous mushrooms are less dangerous.
The primary cause of mushroom poisoning is eating toxic species mistaken for edible look-alikes. People can also be poisoned by eating old, overripe fruiting bodies that have started to decompose, or by improperly preserved mushrooms. Even edible mushrooms that grow near busy highways can become hazardous because they accumulate salts and heavy metals, particularly lead, released into the atmosphere by vehicles.
Now that we’ve acknowledged these dangers, let’s move on to the main topic of this article.
Many mushrooms have long served people well. Some are mentioned as medicinal agents in the works of Dioscorides (1st century AD), Pliny the Elder (1st century AD), and Galen (2nd century AD). Mushrooms also appear in folk medicine texts—handwritten books on medicinal plants. Folk medicine naturally focused first on macromycetes—mushrooms with large fruiting bodies. People used edible examples (such as porcini, champignon, and earthstar), inedible forms (like some polypores), and even poisonous species (like the fly agaric) as remedies.
In Russia as early as the 17th century, people used poultices made from porcini mushrooms to treat frostbite. To this day, such tinctures from porcini are still used in some regions of Siberia. Historically, this mushroom was also used in parts of Germany to treat certain skin cancers.
The red fly agaric was once used to treat rheumatism, nervous disorders, glandular tumors, and even tuberculosis. Even now, in parts of Russia, tinctures made from dried fly agaric fruiting bodies are used for muscle and spine pain. Some modern homeopaths recommend preparations from red fly agaric for severe conditions such as chorea and epilepsy.
A “mushroom ointment” used for gout comes from the common earthstar—made from its so-called “earth oil,” the mucilaginous coating of the mushroom. It has long been used in folk medicine for rheumatism and other ailments.
Another widely known species is the gray dung fungus, which grows in fertilized soil and is tasty when young. People who eat this mushroom must avoid alcohol, because drinking alcohol after consuming it can cause poisoning. A compound similar to the drug disulfiram has been isolated from this “anti-alcohol mushroom.”
The so-called “talking mushrooms” contain clitocybin, a substance reported to have antibacterial properties that have been used against tuberculosis. French doctors have also used this mushroom to treat epilepsy. Antibacterial properties are also reported in champignons, autumn honey mushrooms, earthstars, and some polypores. Folk remedies include applying a cut young earthstar to minor cuts and abrasions to speed healing. The flesh of the fruiting body of the true polypore, which parasitizes deciduous trees, has been used to stop bleeding quickly.
Recently, chaga, a birch fungus, yielded chaga acid, a compound with strong physiological activity. In Russia, chaga extract is now produced and used for chronic gastritis and stomach ulcers. From the fruiting body of another birch parasite, the Piptoporus sponge, researchers isolated a substance with pronounced anti-inflammatory properties that rivals cortisone in strength.
On larch trunks you can find the white fruiting bodies of the larch sponge. In ancient Russia this mushroom was considered medicinal and was used for a range of ailments, including bruises, asthma, tuberculosis, and jaundice. The fruiting bodies contain up to 70 percent resinous substances, many of them physiologically active. Agaric acid, found in these bodies, was used for exhausting sweating associated with tuberculosis. At the end of the 19th century and the beginning of the 20th, Russia was the largest exporter of larch sponge, exporting thousands of poods annually. Later, the USSR organized large-scale collection of this medicinal raw material.
But the biggest advances in medicine have come from a different group of fungi—micromycetes, the microscopic fungi that do not form large fruiting bodies. These humble organisms have provided humanity with powerful medicinal agents such as antibiotics, enzymes, and hormones.
Penicillin was the first antibiotic and it opened a new era in medicine. Since its introduction, it has saved millions of lives from pneumonia, blood infections, epidemic meningitis, scarlet fever, and diphtheria.
After penicillin’s success, scientists isolated thousands of microbial cultures from various substrates and studied them in laboratories. Those searches produced dozens of powerful medications. In production, manufacturers use selectively bred fungal strains that are far more productive than wild isolates. Although the intense rush of antibiotic discovery has slowed, researchers face ongoing challenges—developing new antibiotics to fight resistant bacteria, finding drugs against viruses and malignant tumors, and overcoming the ability of pathogens to adapt to existing treatments. In short, the search continues.
Fungi also play a significant role in vitamin production. Yeasts produce ergosterol, a precursor of vitamin D2, while Mucor species are used to produce carotene.
Mushrooms have helped in the production of enzyme preparations as well. The fungal enzyme amylase is used to treat certain forms of dystrophy and purulent surgical infections, while proteases are used in the manufacture of vaccines, toxins, anatoxins, bacteriophages, and serums.
Microscopic fungi made it possible to produce many steroid hormones on an industrial scale. Chemical synthesis of these hormones was lengthy and expensive; the development of microbial synthesis technology for steroids in the 1950s made hormonal preparations widely accessible. Unlike antibiotic production, this process grows the fungus in a nutrient medium and then adds a steroid precursor; the fungus transforms that compound, effectively neutralizing toxicity and converting it into useful hormones. The process can be extremely efficient, and steroidal preparations produced this way—such as cortisone derivatives—are often more active than some natural hormones.
Organic acids, carbohydrates, and alcohols produced by fungi are also used in medicine. Yet microscopic fungi remain only partially understood. Much work remains to ensure that the full richness of the fungal world is harnessed for human benefit.
