All mushrooms are fungi, but not all fungi are mushrooms
A mushroom is the macroscopic, above-ground portion of the fungal organism. The mycelium is the root portion of the fungi that is rarely seen; it is usually found within a rotting tree trunk, or in a dense underground network. Similar to the way that humans digest and absorb nutrients, mycelia excrete enzymes that break down the waste of the forest, and use this energy to form a mushroom, or a fruit body. When the mushroom has fully matured, seed-like spores are released and wind and insects carry them to their next place of inoculation. The spores, mycelium, and mushroom are all vital aspects of the fungal organism and are, more specifically, different life stages of the fungi. A spore is not a mushroom, a mushroom is not mycelium, and mycelium is most definitely not a mushroom.
Until recently, mycelium was not used medicinally. The energy and time it would take to dig up mycelium from the earth, or separate it from a rotting tree trunk, would far outweigh the medicinal benefit from the small amount of mycelium collected. Traditionally humans, being the innately lazy animals that we are, preferred to spend a few minutes to collect the colorful mushrooms and use them as medicine rather than spend hours digging up and separating out mycelium from rotting flora. If all mushroom products were made from wild harvested fruiting bodies, there would likely be no market for mycelium. Unfortunately, this would not be sustainable, so many companies have developed sterile laboratories where they can cultivate mycelium grown on grain substrate. The same issue returns, however – the cost of the time it would take to separate all the mycelium from the grain is not economically viable. So, the mycelium is not separated from the substrate it is grown on, and the entire block of myceliated grain is dried, powdered, bottled up, and advertised as a mushroom supplement.
Mycelium as a medicine
Mycelium contains many similar medicinal compounds to mushrooms, but often to a lesser degree, with the exception of some polysaccharides. While the majority of research has focused on mushrooms, there is still a fair amount of research touting the health benefits and active compounds present in mycelium. However, these trials utilize mycelium that is grown in a liquid fermentation broth rather than the myceliated-grain that is found in many health food store and apothecary shelves. When mycelium is grown in a broth, the liquid can be strained off and pure mycelium can be processed. However, as mentioned earlier, when mycelium is grown on grain, it is not filtered out or separated and many products can contain up to 60% grain. Pure mycelium from a number of different fungal species absolutely has medicinal value, but that value is heavily diluted when 250mg of your 500mg capsule is oat or sorghum substrate.
A Comparison of Constituents
As mycelium matures into a mushroom, the organism’s energy is focused on reproduction, and there is a vast increase in production of many compounds that happen to be beneficial to humans. One study (1) compared the amount of GABA, lovastatin and ergothioneine in mycelium with that found in mushrooms. GABA, a calming neurotransmitter, was found in equal amounts in both mushroom and mycelium. Lovastatin, a compound that helps to support healthy cholesterol levels, was found to be especially high in the fruiting body of oyster mushroom in comparison to mycelium. Finally, ergothioneine, an extraordinary antioxidant, was found both in oyster mycelium and mushroom, but to a much larger extent in the mushroom.
Another study (2) compared the antioxidant activity of reishi mushroom, spores and mycelium. Reishi mushroom yielded the highest antioxidant activity via phenolic compounds in the extracts. The mycelium contained the highest total level of polysaccharides and single sugar molecules, but the free-radical scavenging properties seemed to be correlated most with the phenolic compounds found in the fruiting body. The chemical makeup of reishi mycelium, fruiting body, and spores powder was explored by another team of researchers (3). They observed the presence of polysaccharides, nucleosides, peptides, triterpenoids and alkaloids present in different fungal life stages. Triterpenoids, especially ganoderic acids, were found in all life stages of the fungal organism, but were by far most abundant in the fruit body, and least abundant in the mycelium. Triterpenoids support a healthy inflammatory response, modulate the immune system, support liver pathways and support healthy cholesterol levels. Their results demonstrated that the polysaccharide content in all parts of reishi were almost the same, with the most upregulated in the fermentation broth.
Polysaccharides, alpha glucans and beta glucans
Polysaccharides are sugar molecules attached by different bonds, some alpha and some beta. The kind of bond determines the physiological activity of the ingested polysaccharide. When exploring the medicinal value of fungi, the beta bond, or β-glucan, is preferred. Many grains contain starch, or alpha-glucans, which can sometimes be confused in the total polysaccharide content of a mushroom supplement. If 60% of a myceliated grain powder contains a high amount of polysaccharides, it is important to differentiate between those derived from the mycelium and those derived from the grain.
β-glucans are the most comprehensively studied constituents in medicinal fungi. Scientists have determined exactly which receptors they bind to, how they bind, where they bind, and the physiological activities that take place afterwards. β-glucans help to support many body systems – a healthy immune system, blood sugar levels and microbiome, to name a few.
The β-glucan content of shiitake fruit body and mycelium was compared by Bak in 2014 (4). Researchers presented a quantitative analysis of β-glucan levels in three sections of the mushroom: stipe (stalk), pileus (cap) and mycelium. The highest β-glucan content was observed in the stipe, or stalk, section of the shiitake fruiting bodies. β-glucan content seems to depend on the degree of fruiting body maturity – the highest level of these compounds seems to be present immediately prior to the period in which the spores begin to ripen (5). Based on this information, mushrooms are likely the best source for β-glucans.
While mycelium is not devoid of medicinal value, most mycelium available for purchase is diluted by grain substrate, and the medicinal value is diluted as well. For this reason, pure fruit bodies that have been extracted and dried or extracted into a quality liquid extract are preferred when using fungi as a medicine. While the ideal product would likely contain pure mycelium mixed with fruiting body, this has yet to exist on the market without grain substrate involved.
- Lo, Y.-C., Lin, S.-Y., Ulziijargal, E., Chen, S.-Y., Chien, R.-C., Tzou, Y.-J., & Mau, J.-L. (2012). Comparative Study of Contents of Several Bioactive Components in Fruiting Bodies and Mycelia of Culinary-Medicinal Mushrooms. International Journal of Medicinal Mushrooms. International Journal of medicinal mushrooms, Volume 14,2021, issue 4 https://doi.org/10.1615/IntJMedMushr.v14.i4.30
- Sandrina A. Heleno, Lillian Barros, Anabela Martins, Maria João R.P. Queiroz, Celestino Santos-Buelga, Isabel C.F.R. Ferreira, Fruiting body, spores and in vitro produced mycelium of Ganoderma lucidum from Northeast Portugal: A comparative study of the antioxidant potential of phenolic and polysaccharidic extracts, Food Research International, Volume 46, Issue 1, 2012, Pages 135-140,ISSN 0963-9969 https://doi.org/10.1016/j.foodres.2011.12.009.
- Chunliang Xie, Shaowei Yan, Zhoumei Zhang, Wenbing Gong, Zuohua Zhu, Yingjun Zhou, Li Yan, Zhenxiu Hu, Lianzhong Ai, Yuande Peng, Mapping the metabolic signatures of fermentation broth, mycelium, fruiting body and spores powder from Ganoderma lucidum by untargeted metabolomics, LWT, Volume 129, 2020, 109494, ISSN 0023-6438, https://doi.org/10.1016/j.lwt.2020.109494.
- Bak WC, Park JH, Park YA, Ka KH. Determination of Glucan Contents in the Fruiting Bodies and Mycelia of Lentinula edodes Cultivars. Mycobiology. 2014 Sep;42(3):301-4. doi: 10.5941/MYCO.2014.42.3.301. Epub 2014 Sep 30. PMID: 25346611; PMCID: PMC4206800.
- Rop O, Mlcek J, Jurikova T. Beta-glucans in higher fungi and their health effects. Nutr Rev. 2009;67(11):624-631. doi:10.1111/j.1753-4887.2009.00230.x