Everybody will agree that a dietary supplement is only worth considering if it has therapeutic potency. Consumers in general automatically assume that all dietary supplements have therapeutic potency. But this assumption is wrong! A problem often overlooked is bioavailability - can our body actually digest and absorb the product ?
In particular mushroom supplements are problematic - if they have not been subjected to an extraction procedure they are therapeutically useless. Only mushroom extracts are worth considering.
In the past decade science has made enormous progress in mapping the active ingredients of medicinal mushrooms. We now know that in general their main bioactive ingredients are beta-glucans (a specific bioactive type of polysaccharides), triterpenes, polyphenols and phyto-sterols. In a dual extract all these ingredients are bioavailable (resulting in additional synergy), in a hot water extract only beta-glucans and polyphenols are bioavailable.
As a consumer, you can use this knowledge to judge both the objective quality and the value for money of the product you intend to buy.
As said before, to be able to guarantee therapeutic potency the mushroom supplement should be an extract. Extraction makes the product more expensive, but it is essential. Most people cannot digest non-extracted mushroom products properly. The $ 18.99-per-bottle products (not to mention even cheaper products) are without exception non-extracted mushroom products. They are easy to spot: they do not give a breakdown of the bioactive ingredients on their supplement facts label, because these cannot be guaranteed in a non-extracted product.
Sometimes they use convincing-sounding but misleading statements such as 'a whole food with its natural ratio of components is always a better choice than concentrations of individual elements, like in extracts'. However, mushroom extraction is never about concentrating specific components (like in herbal extracts), but about making bio-active components bio-available by extracting the indigestible chitin from the mushroom. A statement like that underlines again the fact that most vendors are mostly ignorant about the details of the products they are selling.
Non-extracted products are mostly indigestible (= low bioavailability) and can never deliver therapeutically useful levels of the active ingredients. The producers of these products also can not guarantee the levels of bioactives, making dosing a trial and error process at best. An extensive explanation can be found here. In a consistent quality product the percentages of at least one of the bioactive ingredients is guaranteed and listed on the supplement facts label. The supplement facts label is governmentally supervised and is 100% reliable. Exaggerations or deceiving claims are prohibited.
Summarizing: The only mushroom supplements worth considering are extracts and should guarantee at least one bioactive ingredient such as beta-glucan on their supplement facts label.
In general the best extracts in terms of therapeutic potency are dual extracts (AKA ‘full-spectrum’ extracts - see below) which guarantee several bioactive ingredients on their supplement facts label (e.g. beta-glucans + triterpenes).
Many products list polysaccharides. Keep in mind polysaccharides also include starch, chitin, dextrin and other therapeutically useless compounds, including fillers. Only beta-glucans are bioactive polysaccharides.