Beta Glucans: The Healing Compounds in Mushrooms

 It is absolutely fascinating that one of the most promising remedies for many degenerative conditions is a food! It goes to show that there really is no need for fancy supplements or exotic herbs to maintain good health. Eating whole foods, a range of fruits and vegetables and staying active really is the antidote to modern living. 

The specific food we are discussing today is mushrooms and science is only now beginning to delve into this mysterious world full of promise. Although science is only now confirming what many traditional and indigenous cultures already knew, this is a reminder that eating the whole plant, fungus or herb, is a lot better than chasing after the single constituents that scientists isolate and study. We know that the array of constituents found in plants and fungi work synergistically and that no isolate can do the work of the whole web of interconnected magic. on the other hand, it is wonderful to see the world of science confirm that mushrooms are indeed healers in their own right.

The number of different mushroom species on earth is estimated at 140 000, of which maybe only 10% are known. Meanwhile, of those approximately 14 000 species that we know today, about 50% are considered to possess varying degrees of edibility, more than 2000 are safe, and about 700 species are known to possess significant pharmacological properties.

Medicinal mushrooms have an established history of use in traditional oriental therapies. Historically, hot- water-soluble fractions (decoctions and essences) from medicinal mushrooms were used as medicine in the Far East, where knowledge and practice of mushroom use primarily originated. Mushrooms such as Ganoderma lucidum (Reishi), Lentinus edodes (Shiitake), Inonotus obliquus (Chaga), and many others have been collected and used for hundreds of years in Korea, China, Japan, and eastern Russia.

Medicinal mushrooms contain a wide variety of compounds that show great potential for supporting human health. These class of tonic herbs have proven to stimulate the immune system, reduce stress and anxiety, increase energy and reduce fatigue, boost brain power, memory and focus, improve digestion and gut health, nourish and protect skin health and more.

The healthy constituents in mushrooms include the polysaccharides, triterpenoids, sterols, prebiotics, antioxidant enzymes (lactase, catalase, superoxide dismutase (SOD)), amino acids, polyphenols, proteins, peptides, flavonoids, and digestive enzymes (proteases, lipases) among others. But the most scientifically studied health-promoting compounds in fungi is a specific type of polysaccharide called beta-glucans (β-glucan), more specifically beta-D-glucans.

Beta-D-glucans belong to a group of physiologically active compounds called biological response modifiers. They are naturally occurring and represent highly conserved structural components of cell walls in not only fungi but also yeast and seaweed.

According to this study, mushroom β-glucans provide a unique opportunity for the discovery of novel therapeutic agents and have attracted a great deal of attention due to many health benefits such as immunomodulatory, anticancerous, cardioprotective, hepatoprotective, antioxidative and antimicrobial activities. 

As we mentioned, polysaccharides exist in a variety of sources including fungi, cereals, yeast, bacteria and seaweed. Let’s breakdown their components:

Saccharides are better known as carbohydrates. The simplest forms of carbohydrates are monosaccharides. Examples of monosaccharides include glucose (dextrose), fructose (levulose) and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose and lactose) and polysaccharides (such as cellulose, chitin and starch).

More complex forms of carbohydrates are polysaccharides.

Cellulose is the most abundant polysaccharide in nature. It's what plant cell walls are made of. The second most abundant is chitin, the primary component of fungal and some bacteria cell walls as well as the exoskeletons of insects, arachnids (spiders), and crustaceans (lobster etc.).

Chitin is indigestible to humans but it also contains within it the important beta-glucan compounds that we want to consume. Hot water extraction is the only proven method to breakdown, or rather, “melt away” the chitinous cell walls thereby activating the beta-glucans and keeping them structurally intact.

Mushrooms contain varying amounts of polysaccharides depending on the species of fungi and if the specimen is wild or how it is cultivated. We know that Reishi (Ganoderma lucidum), Maitake (Grifola frondosa) and Turkey Tail mushroom (Trametes versicolor) typically contain higher amounts of polysaccharides (approximately between 20-40% depending on the method of extraction).

Mushrooms may not come to mind as a gut-friendly food, but they are ranked among the best foods for promoting a healthy microbiome. Mushrooms are a rich source of various prebiotic fibers including chitin, hemicellulose, β and α-glucans, mannans, xylans, and galactans. As a prebiotic fiber, they also play a significant role in promoting a healthy microbiome via stimulating growth of beneficial bacteria species, mitigating pathogenic ones, and modulating inflammation to optimize the gut environment, to the extent that they are being looked at as a possible therapy for autoimmune conditions and in reducing risk factors associated with IBD and chronic inflammation.

Mushrooms also enhance both the innate and adaptive immune functions. It has been shown that Beta-glucans act on several immune receptors that stimulate immune cell activity, including T-cells, macrophages, neutrophils, monocytes, natural killer (NK) cells, and dendritic cells, and as a result, pose modulatory effects on both the innate and adaptive branches of the immune system. Beta-glucans enhance phagocytosis and trigger release of various interleukins and cytokines (that also possess cytotoxic anti-cancer properties) such as TNF-𝜶, IFN-𝛄 and NF-𝝹𝜷, while also helping support regulation of the T-helper cell 1 and Th-2 balance for immunological homeostasis.

Mushrooms possess powerful antioxidant properties that promise to aid in our fight against oxidative stress and the chronic health conditions that spring forth from this damaging state. Phenolics, flavonoids, glycosides, polysaccharides, tocopherols, ergothioneine, carotenoids, and ascorbic acid are among the most common antioxidant compounds found in both wild and cultivated mushrooms. These antioxidant compounds protect against oxidation at several levels and through various mechanisms, including scavenging free radicals, deactivating toxic heavy metals, inhibiting lipid hydroperoxides, and regeneration of primary antioxidants. Further, mushroom antioxidant compounds have been shown to induce cell signals and change gene expression, resulting in activation of endogenous enzyme systems. Mushrooms are also rich sources of antioxidant vitamins. The ascorbic acid content of certain species of wild edible mushrooms was found to be higher (100 mg/100 g dry weight of ascorbic acid in the methanolic extract of the wild edible mushroom Cantharellus cibarius) than in some fruits and vegetables, commonly recommended for their vitamin C content. Vitamin E (including tocopherols and tocotrienols) is found in mushrooms, as well as several potent carotenoids including β-carotene, lutein, and canthaxanthin, the antioxidant pigment responsible for making salmon look pink.

The prevalence of vitamin D deficiency has caused several practitioners to amp up their recommendations to consume vitamin D rich foods, but rarely do mushrooms make the list. Although mushrooms may not have the highest source of vitamin D, they will certainly contribute to an individual’s overall intake. The three most commonly consumed mushrooms –the button mushroom (Agaricus bisporus), oyster mushrooms (Pleurotus species), and shiitake mushrooms (Lentinula edodes) – have high concentrations of ergosterol (vitamin D2) which help to strengthen cell membranes, modulate membrane fluidity, and assist in intracellular transport. They also supply lesser amounts of vitamin D3 and D4. The vitamin D content of mushrooms is directly related to its exposure to sunlight; therefore, retail mushrooms grown in atmospherically controlled growing rooms may only possess negligible amounts of vitamin D, but wild harvested mushrooms can contain amounts in excess of 10 μg/100 g fresh weight (about 3 mushrooms).

There are a countless number of studies on mushrooms being conducted and as a rich source of antioxidants, vitamin D, prebiotics, and several crucial vitamins and minerals, mushrooms as well as their protective properties from all kinds of diseases, mushrooms should no longer be treated as a food option governed by preference, but rather a significant element of a health-promoting diet. These unadorned fungi truly reflect the meaning of “food is medicine.”