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Bioavailability of medicinal mushroom supplements

When you buy a dietary supplement, you automatically assume that you will benefit from it. But this assumption is not always justified: quite a few supplements contain limited or no bioavailable bioactive ingredients at all. ('Bioavailable' meaning: the human body is able to digest and absorb the ingredient.)

The average consumer will not be aware of this limited bioavailability (this information is never revealed on the supplement's label) so is basically wasting his money. Examples of ingredients with limited or no bioavailability are e.g. resveratol, green tea extract (ECGC) and betulinic acid.

We want to discuss a whole group of supplements that are mostly useless unless they've been subjected to processing: medicinal mushroom supplements (sold in the form of capsules, powder, tablets, and aqueous solutions/tinctures). Medicinal mushrooms became very popular during the past 10 years, not in the least because of health gurus like David Wolfe, Cass Ingram and Daniel Vitalis. Examples of medicinal mushrooms are Reishi, Chaga, Cordyceps, Maitake and Coriolus, to name a few popular ones.

To cut straight to the conclusion: unless mushrooms (both raw and dried) have been subjected to an extraction process they are basically indigestible for the majority of people and you will not experience noteworthy therapeutic effects. The majority of mushroom products on the market have not been subjected to an extraction process. The bioavailability of the active ingredients is low at best (± 1/30th to 1/50th of a genuine extract) and the term 'extract' is often used in a deceiving way.
 

A 2015 study performed by Bastyr University offers additional proof. While investigating two specific immunological parameters the differences (therapeutic effect) between extracted and non-extracted mushroom products were very obvious.

Technical background

The reason for the limited bioavailability is this: mushroom cells are made of chitin, the same material that covers e.g. insects, lobsters and crabs. Chitin is the hardest all-natural material known to man. Locked in the chitin cell-walls of medicinal mushrooms are the bioactive and therapeutically interesting components. The keyword here is 'locked'.

Humans cannot digest chitin properly; the enzyme chitinase, needed to break down chitin, is not very active in our stomach acid; until recently it was considered to be absent, even. One small study has investigated the chitinase activity in a group of 25 young men. In brief, the outcome was that only 20% of the 25 test subjects were found to have good chitinase activity, and another 20% were found to have zero chitinase activity. 60% had poor chitinase activity. It is quite clear that if you want to be certain you'll get the therapeutic effects you're after you're not going to gamble - you choose an extract.

The therapeutic effects of non-extracted mushrooms are therefore unpredictable at best, not to say negligible. This is also the reason traditional medicine systems that include medicinal mushrooms in their repertoire (like Traditional Chinese Medicine), only use them in decoctions, teas or soups, never simply dried/powdered, in tinctures or raw. Scientific research, a cornerstone in the marketing of mushroom products, is always using extracts.

Extraction procedures

The most common and cheapest extraction technique is hot-water extraction: the hot water will 'melt' the chitin and release the water-soluble bioactive components. The highest yield of bioactive ingredients is achieved when a high temperature combined with high pressure (211-373 ºF and pressure up to 50 psi to prevent disintegration of the moleculal structure of the bioactive constituents) is used. As a second step hot ethanol extraction is used in more sophisticated mushroom products: this will release the non-water solubles as well; basically, all bioactives will become bioavailable when this step is also included. Do not confuse this with an alcohol tincture: simply adding mushroom powder to alcohol will not have a lot of effect. Unlike cellulose (herbal products) chitin does not degrade in alcohol.

Most consumers will have no knowledge of these technical details. You only have the supplement-facts label and a website/brochure filled with power-statements. In brief: you can trust the first one (by law it is prohibited to exaggerate or lie on that label) and the second one you can consider mainly marketing talk, which can have varying levels of truth.

The good thing is that the label will tell you everything you need to know.

Only if the label gives you details like "40% polysaccharides" "10 mg ergosterol" "2% betulinic acid" you can be 100% sure you have a genuine extract. General statements like "contains a high level of beta-glucans", "over 200 phytonutrients!" "contains PSP/PSK" are only found on non-extracted products; genuine extracts will always state the exact numbers. Simply, because they can, plus it provides them with a USP (Unique Selling Point). Non-extracted mushroom products can never claim a guaranteed percentage of whatever active ingredient. Levels do vary between mushrooms even if they were harvested in the same area. This is the case with all natural products.

Extracts or no extracts ?

Finally, the use of the term 'extract' can be very deceiving. Genuine mushroom extracts are in general the result of solvent extraction (hot water, maybe also hot ethanol). The bioactives are freed, diluted and concentrated in the solvent and then isolated.

However, we came across several 'extracts' that used terms like "10:1 extract". This is misleading, because it basically refers to drying or concentrating a large amount/size to a smaller amount/size. It cannot be considered an indication of potency if there is no further specification of bioactives as described above. In this particular case we can state that e.g. 10:1 means it is simply a dried and powdered mushroom: mushrooms are often ± 90% water, so a completely dry mushroom has been reduced to 10% of its original weight. Herbal tinctures always use this indication of potency, but mushrooms are not herbs and do not disintegrate in alcohol or cold water, like dried herbs do.

Only if the label gives you details like "40% polysaccharides" "10 mg ergosterol" "2% betulinic acid" you can be 100% sure you have a genuine extract. General statements like "contains a high level of beta-glucans", "over 200 phytonutrients!" "contains PSP/PSK" are only found on non-extracted products; genuine extracts will always state the exact numbers. Simply, because they can, plus it provides them with a USP (Unique Selling Point). Non-extracted mushroom products can never claim a guaranteed percentage of whatever active ingredient. Levels do vary between mushrooms even if they were harvested in the same area. This is the case with all natural products.

Extracts or no extracts ?

Finally, the use of the term 'extract' can be very deceiving. Genuine mushroom extracts are in general the result of solvent extraction (hot water, maybe also hot ethanol). The bioactives are freed, diluted and concentrated in the solvent and then isolated.

However, we came across several 'extracts' that used terms like "10:1 extract". This is misleading, because it basically refers to drying or concentrating a large amount/size to a smaller amount/size. It cannot be considered an indication of potency if there is no further specification of bioactives as described above. In this particular case we can state that e.g. 10:1 means it is simply a dried and powdered mushroom: mushrooms are often ± 90% water, so a completely dry mushroom has been reduced to 10% of its original weight. Herbal tinctures always use this indication of potency, but mushrooms are not herbs and do not disintegrate in alcohol or cold water, like dried herbs do.

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