Beta-Glucans: Secret Truth Behind The Healing Compounds in Medicinal Mushrooms

Medicinal mushrooms, or functional mushrooms, contain a wide variety of compounds that show great potential for supporting human health in many areas.

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, restore hormonal imbalance, 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. (1)

With almost 150 years of combined research, the β-glucans from other sources like yeasts and cereals is well summarized in the literature, but recently, mushroom β-glucans have come into an exciting new light of research.

According to this study, mushroom β-glucans found in mushroom latte products 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. (2)

Mushrooms are soo hot in the health and wellness industry right now and their fast rise to fame is largely due to the health benefits that science is beginning to discover about the positive effects beta-glucans can have on the body.

You can literally pick up a range of concentrated mushroom extract products–powders or pills–at most health food stores and supermarkets today.

But beware: there’s a dirty little secret in the mushroom industry.

Mushroom anatomy is made up of many parts but β-glucans are certainly the most valuable and widely studied compounds in medicinal mushrooms.

Many companies will boast and make claims about their high polysaccharide numbers on their product labels, packaging and marketing.

But is this metric (total polysaccharide content) really a measurement of a quality mushroom product?

Do high polysaccharides = high quality?

There’s more to this story so don’t be fooled by those high polysaccharide numbers just yet. They’re not always reflective of the total β-glucan content, those compounds which are most beneficial for our health. It’s important to understand the differences in polysaccharides.

There are significant flaws in the testing and analysis of mushroom β-glucans so let’s nerd out and find out how you can get the best bang for your buck and make informed health decisions about which medicinal mushroom products you should purchase.

Also, learn how you can avoid buying mushrooms that are fed junk food!

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What are Polysaccharides?

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.

Polysaccharides are long-chain (polymeric) carbohydrate structures, formed of repeating molecular units–either mono-saccharides (glucose, fructose, galactose) or di-saccharides (sucrose, lactose) joined together by glycosidic bonds. They range in structure from linear to highly branched. Some examples include storage polysaccharides such as starch and glycogen and structural polysaccharides such as cellulose and chitin.

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.

This is why, traditionally, mushrooms were always cooked by herbalists, practitioners, doctors and researchers and why the majority of mushroom supplements on the market are either hot-water extracted or hot-water/alcohol extracted.

Even the culinary store-bought mushrooms need to be cooked which means, no more raw mushrooms in your salads!

Mushrooms contain varying amounts of polysaccharides depending on the species of fungi and if the specimen is wild or how it is cultivated. For example, 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). (5)

Beta-Glucans: The Best Type of Polysaccharide

Mushrooms (or basidiomycetes) contain many different forms of polysaccharides but the most important compounds are identified as the beta-D-glucans.

Beta-glucans come in various forms. The main one has what is known as 1-3,1-6 branching, or (1-3)(1-6) beta-D-glucans. This refers to the structural characteristics with particular designations (1-3) describing the linking pattern in the long chain molecule. (1-3)(1-6) beta-D-glucans are specific to fungi and yeast.

Oats and grains also contain beta-glucans but they have a different branching structure, which is (1-4)-beta-glucans.

The term beta-glucan refers to the beta-linked glucose molecules that form the typical fungal polysaccharide. The important difference when comparing the various sources of polysaccharides is that beta-glucans (and cellulose) are beta-linked while other forms such as starch are alpha-linked, otherwise known as alpha-glucans (α-Glucans).

This leads us to the problems with alpha-glucans (starch/glycogen) and their cause for much of the confusion within the functional mushroom industry.

Mushroom Products Contain Fillers Known as Alpha-Glucans

Another group of polysaccharides are called alpha-glucans and include compounds like glycogen, pullulan, dextran and starch.

Starch is a very common polysaccharide that is present in many staple foods such as potatoes, corn, rice and grains.

Fungi only contain very small amounts of starch, less than 3% average of the dry weight–this study measured the alpha-glucan content of twenty pure mushroom samples (fruiting bodies) and the analysis showed that most of the samples contained <4% and in many, it was even lower at <1%. (7)

The primary polysaccharides in mushrooms are beta-glucans. It’s unnatural to contain high levels of alpha-glucans, and what’s been uncovered is that a large number of functional mushroom products on the market today contain high levels of alpha-glucans and low levels of beta-glucans. (7)

This is due to the prevalence of mycelium grown on grain (MOG) products in the market.

In fact, it's suspected that almost all North American grown medicinal mushroom products use the MOG cultivation method and have shown very low beta-glucan content.

Commercially, mushroom products are produced in two ways: grown and harvested as mushroom fruiting bodies or alternatively grown as mushroom mycelium over a sterilised grain base.

A depiction of Mushroom (Basidiomycete) Life Cycle

Mycelium on Grain (MOG) Cultivation

Is it really what you think it is?

The mycelium is likened to the root structure of a fungal organism and one stage of the full life cycle of a mushroom (above is an example of the mushroom life cycle). The second stage is the development of the mushroom (fruiting body) and the final stage is the production and release of the spores (seeds), which completes the cycle and is then repeated in nature (Note: there are more than three stages but this is the simplest way to describe the life cycle of a mushroom).

MOG cultivation is achieved by growing the fungal mycelium on a sterilised grain substrate, usually brown rice.

The problem with this method is that a lot of residual grain (starch) remains in the final product and isn’t filtered out in the process. What you’re actually getting, in the end, is a mushroom product high in alpha-glucans (starch) and low in the bioactive beta-glucan compounds.

Mycelium growing on grain

This growing method (MOG) results in an inferior product compared to other cultivation techniques that utilise mushroom fruiting bodies that are grown on traditional wood substrates.

A 2016 study examined various medicinal mushroom products on the market to determine their α-Glucan and β-glucan content. The researchers behind the study noted: most of the products studied are “mycelium propagated on grain.” Bottled products containing encapsulated mycelium/mushroom powder.

Table 10. (below) from the study shows the total glucan, α-Glucan and β-glucan content per g/100g for a number of different commercial products that were purchased via Amazon.com.

Take note of sample #5 Ganoderma lucidum (Reishi), it shows high amounts of α-Glucans and nominal β-glucans. Samples #8 Cordyceps sp. (ascomycete) and #12 Inonotus obliquus (Chaga) show similar results. The Chaga sample was the worst testing for ~0.0 β-glucan levels.

Clearly, after reviewing the analytical data in table 10., it’s obvious that a bulk of the starch in the grain remains intact and is by far the major glucan present in the final product. This is completely unnatural since we know that mushrooms only contain very small amounts of starch, less than 3% on average of the dry weight.

Furthermore, the companies producing and selling these mushroom products often tout and market their high polysaccharide numbers (Total glucan = α-Glucan + β-glucan) on their products without disclosing to the consumer the accurate levels of beta-glucans.

Samples #2, #3 and #5 for example, could claim >60% polysaccharides even though after reviewing Table 10., we know that those polysaccharides are mostly alpha-glucans and contain low beta-glucans levels. This is not what we desire because alpha-glucans contain no nutritional benefits. It’s the health-promoting beta-glucans that we want.

And did you know: according to the FDA, the identity of mycelium is different than that of a mushroom. Mycelium is not allowed to be considered a mushroom by the FDA. However, companies that sell mycelium-based products still make those claims and cleverly hide it by revealing their total polysaccharide numbers, not by the true beta-glucan or starch content.

Log-grown Reishi mushroom (Ganoderma lucidum) fruiting body

Mushroom Fruiting Body Extracts For Your Health

Most of the scientific research in relation to the purported health benefits of medicinal mushroom extracts have been conducted using the fruiting bodies. Mushroom mycelium has shown to have some health benefits when extracted correctly (not on a grain substrate) but it is less effective than the fruiting body.

Mushroom fruiting body extracts offer a more potent and higher quality product than mycelium extracts. Concentrated fruiting body extracts contain more bioactive levels of beta-glucans and a wider array of nutritional components compared to the mycelium.

Growing mushroom mycelium on grain was created as a cheap alternative for manufacturer’s and is very fast to produce. Unfortunately, the results and benefits are not nearly the same.

With mycelium on grain mushrooms, you are essentially getting a lot of ground rice with low potency mycelium.

Where are the health benefits? Why spend all your hard earned money on a “mushroom” product that provides no results?

And if you’re trying to eliminate grains from your diet or following a paleo diet, do you really want to be consuming all those extra grains?

This is what’s happening in the marketplace and many consumers are unaware of what’s going on and what they’re actually eating.

Grains Are Junk Food For Mushrooms

Just like humans, mushrooms simply cannot survive on a junk food diet, thrive and be healthy. Fungi also need a healthy diet with a balance of vital nutrients to become healthy and strong.

When cultivating mushrooms artificially (without including nature), the process begins by feeding the spores a limited spectrum of foods such as agar. This ensures that the mycelium can grow quickly and become stable for the next medium in the growing process. If that next medium is a grain substrate, then the mycelium will be eating junk foods for its whole lifespan. Imagine what would happen if our kids were brought up on only junk foods?

Another comparison is this: ask a meat-eater, “Would you prefer to eat grass-fed steak or steak sourced from grain fed cows?" The healthier option is fairly obvious.

For the mycelium, a food source like grain means that the mycelium does not diversify as extensively without the proper nutrients and therefore, end up with limited nutrient profiles. Furthermore, this whole process is very unnatural compared to a wild mushroom in its natural growing environment.

It’s no surprise that results such as those shown in Table 10., have highlighted mycelium/mushroom products with poor nutrient profiles and wildly imbalanced ratios of alpha-glucans and beta-glucans.

Using a wood substrate for growing mushroom fruiting bodies is a much more natural growing method and closely resembles the wild environment in which a mushroom naturally grows in.

Wood substrates are the optimal food source for mushrooms (basidiomycetes)–the same as what they consume in nature–and contain the right nutrition and metabolites equivalent to produce a healthy and strong mushroom rich in the right components to support human health.

While the wood log is a food source equivalent to a balanced human diet, it also contains outside competition from other organisms within its "semi-wild" environment.

By eating the right foods and coming out on top as the dominant organism in the log, this produces a super mushroom with adaptogenic qualities. Not only this, but there may also be unquantifiable relationships that exist with other organisms that are not competitive, but rather synergistic with the mycelium.

Therefore, it is far more beneficial for the mushroom to be grown on a natural substrate like wood rather than a cheaper and unnatural grain alternative.

Ideally, for our best health, we want to consume mushroom fruiting bodies that are grown on wood substrates (like logs) and have been hot water or dual extracted (hot water/alcohol) with a final product that is rich in beta-D-glucans.

Appropriate Testing for Beta-Glucans

There is concern within the regulatory community regarding the identity and purity of mushroom products on the market. (7)

It’s worth noting that most beta-glucan testing methods have been designed specifically for grains. However, grains are (1-4)-beta-glucans and therefore, grain specific tests are not suitable to measure the (1-3)(1-6) beta-D-glucans in mushrooms accurately.

The same authors of the above study, Dr Barry McCleary at Megazyme International in Ireland, have developed a new test method specifically for testing the beta-D-glucans in mushrooms. This testing method is the gold standard for beta-glucan testing today and is used by the USDA and other scientific research papers to precisely measure the beta-D-glucans in mushrooms.

Another simple way to detect alpha-glucans in your mushroom products is via a simple starch test that you can literally do at home using iodine.

At Teelixir, we utilise the Megazyme method to test all our mushroom extracts. You can view the potent results on each product page.

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References and Resources:

1. Novak M, Vetvicka V (2008). Beta-glucans, history, and the present: immunomodulatory aspects and mechanisms of action. J Immunotoxicol. 2008 Jan;5(1):47-57. doi: 10.1080/15476910802019045.

2. Asma Ashraf Khan, Adil Gani, Firdous A.Khanday, F.A. Masoodi (2018). Biological and pharmaceutical activities of mushroom β-glucan discussed as a potential functional food ingredient. Bioactive Carbohydrates and Dietary Fibre Volume 16, October 2018, Pages 1-13 https://doi.org/10.1016/j.bcdf.2017.12.002

3. http://www.edinformatics.com/math_science/what_are_polysaccharides.htm

4. Mark Stengler, N.D. (2005). The Health Benefits of Medicinal Mushrooms. Basic Health Publications, Inc.

5. Sari, M., Prange, A., Lelley, J. I., & Hambitzer, R. (2017). Screening of beta-glucan contents in commercially cultivated and wild growing mushrooms. Food Chemistry, 216, 45–51.

6. Chilton, J. Nammex: Redefining Medicinal Mushrooms, 2015 - http://www.nammex.com/redefining-medicinal-mushrooms/

7. McCleary, B. V., & Draga, A. (2016). Measurement of Beta-Glucan in mushrooms and mycelial products. Journal of AOAC International, 99(2), 364–373. http://doi.org/10.5740/jaoacint.15-0289

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