In part 1 of this series, I discussed mushrooms' lifecycle and their different parts. This week, I will dig into the relationship between polysaccharides and mushrooms.

What types of polysaccharides are in mushrooms?

To answer this question correctly, it is vital first to understand what polysaccharides are. In simple terms, Polysaccharides are large carbohydrate molecules containing many small sugar molecules (monosaccharides) bonded by a glycosidic linkage (a bond that joins a carbohydrate molecule to another group). They are the most abundant carbohydrate found in food. Polysaccharides consist of more than ten monosaccharide units linked together. Polysaccharides form when monosaccharides and disaccharides link together (resulting from a dehydration process). The sugars participating in this bond are called residues. 

Mushrooms contain a wide range of non-starch polysaccharides (carbohydrate fractions excluding starch and free sugar) like chitin, beta-glucans, alpha-glucans, hemicellulose, mannans, xylans, and galactans. Non-starch polysaccharides are distinguished into soluble and insoluble fractions, with up to 90% being insoluble fractions. Most (around 80%) of insoluble polysaccharides are chitin, including beta-glucans bound onto chitin or protein. 

It is believed that the primary polysaccharides found in fungi are beta-D-glucans, which come in various forms (beta 1-3 and 1-6) and are specific to fungi and yeast. Other polysaccharides found in mushrooms are Alpha-glucans like glycogen, dextran, pullulan, and starch, which are not thought to provide the same nourishing qualities as beta-glucans. This belief tells you only part of the story and may be based on flawed science.

You may have noticed that most medicinal mushroom product labels focus on only beta-glucan levels; therefore, some important points must be clarified. Here are accurate facts about beta-glucans.

• Beta-glucans are a classification of compounds known as polymers. 
• There are hundreds of beta-glucan shapes and sizes, and while some are biologically active, others are not. Furthermore, not all are immunologically active.
• Each species of fungi may contain a different beta-glucan. 
• Beta-glucans can differ in function, solubility, and interaction with other molecules. 
• While beta-glucans are potent compounds, they are just one variable of a wide range of compounds responsible for a mushroom's many nourishing qualities. 
• Ultimately, Beta-glucan levels are not necessarily the telltale sign of a product's effectiveness. 

It is, therefore, misleading to state that beta-glucan levels are the determining factor in the effectiveness of a mushroom product. Beta-glucans are most effective when they work with all other constituents found in mushrooms, and if one or more are missing, it can change how effectively the end product works. For example, a study discussing the polysaccharide K(PSK) from turkey tail mushrooms showed that when lipase was applied, it reduced the immunological response of PSK by 80%. This study shows the importance of the associated lipids bound to the beta-glucans and that their independent presence is insufficient to obtain maximal benefits. https://link.springer.com/article/10.1007/s11418-014-0879-z

Bioactivity and mushroom preparation

It is widely agreed upon that to get the most nourishment out of your mushrooms, they should be cooked, heat treated, and, or extracted. Raw mushrooms are considered largely indigestible due to their rigid cell walls composed of chitin. It is also agreed that raw mushrooms have pathogens and toxins that can potentially cause harm and are heat-sensitive. Proper heating and preparation of the mushrooms softens the fungal tissue, allowing access to all the nourishing compounds. 

An article showing the effect of different drying methods on mushrooms showed that each technique had vastly differing physicochemical and antioxidant properties.

https://www.researchgate.net/publication/251629198_Effect_of_different_drying_methods_on_physicochemical_properties_and_antioxidant_activities_of_polysaccharides_extracted_from_mushroom_Inonotus_obliquus

Polysaccharides can support a wide range of actions in the human body. They have been shown to have immunological, neurogenic, cardiovascular, microbiome effects and other nourishing qualities. 

For example, Lion’s Mane mushrooms contain many bioactive compounds like Polysaccharides, Polypeptides, Prebiotic fiber, Hericenones, and Erinacines. Some of these bioactive compounds have been linked to neurogenesis (the growth and development of nerve tissue) because preliminary research on Lion’s Mane suggests its potential to support this process by possibly preventing and repairing nerve damage.

In a small double-blind, placebo-controlled human study understanding the effects Lion’s Mane mushrooms have on mild cognitive impairment, “At weeks 8, 12 and 16 of the trial, the Yamabushitake group showed significantly increased scores on the cognitive function scale compared with the placebo group. The Yamabushitake group's scores increased with the duration of intake, but at week 4, after the termination of the 16 weeks of intake, the scores decreased significantly. Laboratory tests showed no adverse effect of Yamabushitake. The results obtained in this study suggest that Yamabushitake is effective in improving mild cognitive impairment.” https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.2634

Stay tuned for Part 3 of this series, in which I will discuss whether medicinal mushrooms are considered true adaptogens.

Michael Stuchiner is a Master Herbalist and proud graduate of The School of Natural Healing and has worked in different areas of this field for over 25 years. He is a retired elite-level powerlifter who competed for 27 years. As an avid international traveler, he is passionate about the use of medicinal and tonic herbs and local markets in the 35 countries he has visited. Michael makes his mark in herbal medicine through the hundreds of articles he has written and his YouTube channel (A Master Herbalist Perspective). He is considered a true educator in this field.