I have been working with plants as medicines for 30 years now and curiously, I have largely ignored mushrooms (except, that is, for being an avid eater of them). I was so single-mindedly focused on herbs it seemed there was no space in my brain for another phylum. Then a series of events unfolded which lead me, ushered me, into a voyage of medicinal mushroom discovery. I am now a convert and a mycophile! This blog is the first installment of my mushroom journey.
Mushrooms Are Special
It was only discovered recently, in the 1960’s, that fungi and mushrooms belong to the evolutionarily ancient and distinct kingdom or phylum of Fungi. Prior to this, fungi were considered a type of plant. Interestingly animals, including us, are more closely related to fungi than plants, sharing about 30% DNA. This underscores and highlights some of the foundational metabolic functions and pathways that are intertwined throughout nature. A good example is fungal ergosterol, which is both chemically and biologically remarkably similar to human cholesterol and is a precursor to vitamin D2. This shared biology also explains why some fungal diseases are so hard to treat (think: tinea, candida and dandruff) and why anti-fungal pharmaceuticals can have significant side effects, e.g hepatotoxicity.
Fungi play a crucial and commonly unseen role throughout the entirety of the web of life. Fungi and plants share a symbiotic relationship such that there would be no plants without fungi. Fungi are the grand disassemblers of nature, breaking down everything organic and mineral. Without fungi, we would have no soil, no organic matter and we would all be walking waist deep in organic detritus! Fungi can be microscopic (think Penicillium) or macroscopic, and it's the macroscopic fungus or the macrofungus that we commonly refer to as mushrooms (think Button Mushroom or Shiitake). A mushroom is simply a fruiting body, produced by the fungi’s filamentous body or mycelial network. Using a plant analogy, if a mushroom is equivalent to an apple then the remainder of the apple tree, including, leaves, twigs, branches, trunk and roots represents the mycelial network.
There are a vast number of fungal species, with current estimates being at around 3 million (compare this figure to that of other kingdoms: Animalia with an estimated 7.7 million, and Plantae, which only has about 320 thousand species). Much of the fungal world remains undiscovered, with only about 6% currently identified. Similarly, only about 10% of the world’s estimated 150,000 mushroom (macrofungus) species are identified. There is yet much to learn!
Our common vernacular uses the term mushroom very loosely, to describe the various macroscopic fruiting bodies of fungi. The most recognisable style of mushroom with stem, cap and gills are referred to generally as agarics. Other distinguished morphologies can be known commonly as boletes (e.g. the delicious Porcini), puffballs (who hasn’t kicked one as a child), brackets (e.g. the mushroom of immortality, Reishi) and the smelly stinkhorns, etc.
Fungi offer a spectrum of value to humans that extends from utility (eg. maintaining fire, making textiles, even teething rings for babies), to culinary, to medical, to sacramental and spiritual. Nowadays fungi are being used in many novel ways such as bioremediation of polluted sites and toxic waste and as a lightweight packaging in high-end goods. In this blog I would like to begin the discussion with edible fungi, not only as a source of general nutrition, but also as a powerful health-enhancing addition to the diet and as a medicinal supplement.
From a biological, physiological, and evolutionary point of view, it makes perfect sense for us to be eating mushrooms on a regular basis. Indeed, it is highly likely (although difficult to prove) that mushrooms played a significant and under-appreciated role as a food and medicine for ancient humans.
The evidence illustrating how our immune systems are pre-programmed, hard-wired, to communicate with and positively respond to the ingestion of mushrooms is a compelling argument for our evolutionary entanglement. Strangely however, the modern Western world is somewhat mycophobic when compared to more traditional cultures.
By virtue of the unique polysaccharide chemistry in fungal cell walls, all edible mushrooms have medicinal properties to varying degrees, with immune system modulation as a common theme. Their medicinal value also varies with the content of their species-specific chemical compounds, as we see in medicinal plants. Not all medicinal mushrooms are edible as a culinary ingredient though. Some famously medicinal fungi, for example bracket-forms like Trametes versicolor (Turkey Tail) or Ganoderma spp. (eg. Reishi), have tough, woody, leathery textures that cannot be chewed and/or have an unpalatable bitter flavor. Such species are easier to consume as a powder or extract (eg. infusion, decoction, tincture) and so are taken specifically for their healing or supporting qualities. Mushrooms that have a suitable texture and taste are numerous though, and can be easily incorporated into the diet, much as our foraging ancestors would have.
Mushrooms to Eat
The mushrooms pictured above are called Scaly Flame Caps, Pholiota adiposa. These are an example of a mushroom with a classic agaric form that grow wild in Australia. I have cultivated these from spawn I purchased from a supplier. Mushrooms are easy to grow at home, I recommend giving it a try!
The most familiar of the edible agarics has to be Agaricus bisporus. Its fruit body is known by many names, most commonly as the Button Mushroom if harvested in immaturity, the Crimini or Swiss Brown when it achieves color, and as the Portabello once mature. Many other members of this genus make good eating as well.
Here are some other familiar fungal faces you would do well to find in your kitchen!
The Auricularia spp. (generally referred to as Wood Ears) are commonly consumed in Asia, as are the Tremella spp. (commonly Jelly-Fungi). Both are virtually tasteless but provide texture in dishes. The wood ears are slippery, rubbery and crunchy, the jellies are similiar with a particularly rubbery, gelatinous feel that is often desired for desserts in Asia. Both have historical value in folk medicine being associated with cooling, mucilaginous activity on inflamed mucous membranes especially.
So far these mushrooms have all belonged to the same fungal division, Basidiomycota. A separate division, Ascomycota, yields less familiar fruit body styles. Here we see some peculiar-looking mushrooms including the much-loved Morels (Morchella spp.) and particularly intriguing Cordyceps (Cordyceps and Ophiocordyceps spp.). The ever-treasured Truffle is another member of this strange division with a fruit body that forms underground.
Chaga is similiarly amorphous as the truffle but is completely different, belonging to the Basiomycota group but with such inconspicuous fruit bodies they are rarely witnessed. What we do see, and consume, is a hardened mass of sclerota rather than a fruit body. This unusual formation is most commonly found jutting out from the bark of birch trees.
Mushrooms Are Nutritious
There is a myriad of nutritional benefits from eating mushrooms. It is probably fair to say that mushrooms support just about every body system. Firstly, they are high in protein. Dried button mushrooms can have about 7% protein. Some people quote as high as 20-40%, but the methods used to detect proteins in mushrooms were not originally very accurate, which has resulted in these inflated numbers [1].
Low in digestible carbs and total fat, mushrooms offer healthy, polyunsaturated fatty acids. Being high in fiber, they are emerging generally as excellent prebiotics and positive modulators of the microbiome. They are also great sources of many minerals, including rare offerings such as organic germanium in Reishi. Many vitamins are available from fungi, especially vitamins C, D, B1, B2, and even B12 [1].
Dietary Mushrooms For Immune Health
There is an interest emerging in studying the effects of mushrooms in our diets. Even with just a few of these early studies, we begin to see the remarkable influence regular dietary mushroom intake can have on our physiology!
The humble button mushroom has not generally been thought of as a medicinal agent but rather are a staple dietary element enjoyed commonly around the world.
In one small study from the University of Western Sydney [2], 24 healthy adults were randomized into two groups to examine the effects of button mushroom intake in the diet over a 3-week period. For the first week of the study, the experimental cohort consumed 100 grams of blanched button mushrooms per day with their meals, then returned to their normal diet for the following 2 weeks. The control group continued their normal diet for 3 weeks (no placebo was used). The primary outcome measure was secretory immunoglobulin A (sIgA), measured at commencement of the study and then weekly for 3 weeks. sIgA is a marker of our adaptive mucosal immune defenses, and so indicates the health and vitality of our immune system at mucosal barriers. Mushrooms consumption can have a lasting effect on immune system function (called trained innate immunity which I will discuss in a future blog) and this study design was trying to understand this by measuring SIgA one and two weeks after cessation of mushroom consumption.
What is fantastic about this study is that it demonstrates dietary button mushroom intake significantly increases sIgA in a sustainable dose, quickly, and with lingering effects! At the end of one week of mushroom intake the subjects had 53% increase in SIgA over baseline, and then at the end of the second week without any mushroom intake SIgA was 56%, before returning to baseline at the end of the third week. There was no change in the control group SIgA. Eating 100 g of mushrooms every day or so is a pretty easy way to bolster our protection against microorganisms and infection, but it may be too much for the average person! I think a more achievable 50 g would likely have a similar effect.
Another great example of a familiar culinary mushroom with medicinal qualities, particularly for its protective effects in lung infections is Pleurotus spp.: the Oyster Mushrooms. The most poignant illustration of the Oyster Mushroom’s effects on our health comes from a series of four European studies conducted on children with recurrent respiratory tract infections (RRTI) [3]. With about 150 children per study, their average ages from 3-6, three trials were open-label, and one was double-blind and placebo-controlled.
All studies demonstrated statistically significant reductions in the frequency of RRTIs! The annual incidence of these events (which include otitis media, common cold, pneumonia, tonsillitis, laryngitis, bronchitis, influenza, and other infections with influenza-like symptoms) reduced by approximately half, which is hugely impressive. There were also significant improvements in other areas across these studies including reduced emergency room visits and reduced days off from kindergarten/school.
The dose for these studies was 10 mg/kg of insoluble beta-glucans per day (approx. 100 mg for 10 kg child) for 3 months, with a 3 month follow up. While these studies used a polysaccharide extract rather than whole mushrooms in the diet, I estimate the 100 mg extract would be roughly equivalent to about 10 g fresh Oyster Mushroom or up to a third of an ounce daily; this is easily achievable!
Lastly I will highlight a fascinating study [4] that looks at another delicious mushroom from kitchens around the world, Lentinula edodes, Shiitake. In this trial, 52 healthy adults were randomized to add either five or ten grams of dry Shiitake to their daily diet for four weeks (5 gram of dry Shiitake is equivalent to 4 or 5 fresh mushrooms ). Regular Shiitake consumption resulted in significantly improved immunity, as seen by improved cell proliferation and activation and an increase in sIgA production. (Eating 5 g gave similar outcomes to eating 10 g). These outcomes reflect an improved capacity of the immune system to respond more efficiently and effectively to assault/damage/infection. The changes observed in immune system messaging molecules (cytokines) and serum CRP levels also suggest these improvements occurred under conditions that were less inflammatory than those that existed before consumption. In other words, a dose-dependent immune enhancement was observed with simultaneous promotion of anti-inflammatory markers! A weakness of the study was a lack of a placebo group.
With these few examples, we get a glimpse into the nutritional and medicinal power of mushrooms. What is it that gives mushrooms these magical, mysterious, and medicinal effects upon our immune function? The key element is the unique polysaccharides found in fungi. While different species will have their own versions, with specific effects, the take-away here is that all mushrooms have some form of these extremely pharmacologically active molecules that we do not often find in other sources from nature. We can have a deeper look at these fungal polysaccharides in a future post.
In the meantime, we would all do well to concentrate on optimizing our dietary mushroom intake!
The Take-Away: Eat More Mushrooms!
I recommend cooking with mushrooms, but many can be eaten raw. We do need to be cautious with some fungi, particularly raw shiitake, which can cause a type of allergic skin reaction in those susceptible, however cooking prevents this. Just make sure you cook your Shiitake!
For health maintenance, I recommend at least three or four serves of mushrooms a week. The exact dose depends on the type of mushroom but typically, within the range of 4 to 10 g (dry weight) will achieve a therapeutic dose or up to 50 g fresh weight. I have adopted this philosophy in my kitchen, so I typically consume around four grams of a combination involving at least Shiitake and Maitake every day. One of the ways I achieve this is via my mushroom-enhanced Immunity Flatbread.
How do you incorporate mushrooms into your diet? I do invite you to share your experiences of incorporating mushrooms into your regular diet, in the comments. I would love to hear your recipe ideas as well.
I also recommend mushrooms as a daily supplement for a wide range of health challenges and for longevity. Some of my favorites are Shiitake, Cordyceps, Lion’s Mane, Chaga, Reishi, Maitake, Oyster, Turkey Tail, and Tremella... and I will discuss some of this in future posts.
References
[1] Agrawal DC, Dhanasekaran M. Medicinal Mushrooms: Recent Progress in Research and Development. Singapore: Springer; Kindle Edition. 2019.
[2] Jeong SC, Koyyalamudi SR, Pang G. Dietary intake of Agaricus bisporus white button mushroom accelerates salivary immunoglobulin A secretion in healthy volunteers. Nutrition. 2012;28(5):527-531. doi:10.1016/j.nut.2011.08.005
[3] Jesenak M, Urbancikova I, Banovcin P. Respiratory Tract Infections and the Role of Biologically Active Polysaccharides in Their Management and Prevention. Nutrients. 2017;9(7):779. doi:10.3390/nu9070779
[4] Dai X, Stanilka JM, Rowe CA, et al. Consuming Lentinula edodes (Shiitake) Mushrooms Daily Improves Human Immunity: A Randomized Dietary Intervention in Healthy Young Adults. J Am Coll Nutr. 2015;34(6):478-487. doi:10.1080/07315724.2014.950391