Our buying criteria for reishi are four short lines. This is the working behind them — the figures we screen on, where they come from, and what they actually prove. You do not need any of it to choose a reishi. It is here because we would rather show it than ask you to take our word.
Whether the product is made from the mushroom itself or from the grain the mycelium was grown on. Everything below is a way of answering that one question.
Beta-glucan is the fiber that reishi is bought for. A real hot-water extract of the fruiting body tests around 35 to 50 percent, and 35 percent is the routine commercial specification. A dual extract reads lower, because the alcohol fraction dilutes it. Anything advertised only as “polysaccharides” is a wider category that includes ordinary starch, which is why filler-heavy products lead with that word.
This is the figure almost nobody publishes, and it is the one that settles the question. Alpha-glucan is starch. Real reishi fruiting body runs about 0.1 to 0.6 percent. Mycelium grown on grain runs 35 to 60 percent, because most of what is in the jar is the grain. Measured examples: a reishi mushroom extract at 49.1 percent beta-glucan and 0.6 percent alpha-glucan; myceliated grain at 6.2 percent and 43.1 percent. A brand that publishes its beta-glucan and not its alpha-glucan has published the flattering half.
The cheap colorimetric assay used for “total triterpenes” is not specific, so a large number there means very little. The honest form names the individual ganoderic and ganoderenic acids and measures them properly. When a label advertises a big total triterpene percentage and names nothing, treat the number as decoration.
Of more than twenty brands checked in August 2026, exactly one published both glucan figures on a signed, lot-specific certificate. Several publish a certificate link that is an image scan with no readable text, or that returns an error. One brand states on its quality page that test results are available on its product pages; they are not, and three plausible certificate addresses do not exist.
A 2017 study of nineteen reishi supplements bought in the United States found that 26.3 percent matched their labels, and that starch-like polysaccharides were present in 68.4 percent. ConsumerLab's 2026 round found two of seven products failed on beta-glucan.
Because the buying section is how we chose, not homework for you. A page that asks a reader to compare glucan percentages has handed them our job. The page says the product should be made from the mushroom rather than from grain, and that the brand should publish results you can see. This is what we check when we apply that.
We have no product of our own and take no payment for a place on a list. Where a figure below is not ours, the source is named so you can check it yourself.