Beta-Glucan Testing Methods: Why Lab Results Vary Between Mushroom Supplement Brands

Why Two Beta-Glucan Numbers on Two Labels Rarely Mean the Same Thing

Lab results for beta-glucan content vary between mushroom supplement brands because labs don’t all use the same test. Some methods measure only the fungal beta-glucans that matter for potency claims. Others measure total polysaccharides, which lumps in starch and other carbohydrates that have nothing to do with a mushroom’s active compounds. A “40% beta-glucan” claim built on one method can describe a very different product than the same claim built on another.

This guide walks through the main testing methods, what each one actually measures, and what a certificate of analysis can and cannot tell you about the bottle in front of you.

The Core Problem: Not All “Polysaccharide” Tests Measure Beta-Glucan

Fungal cell walls are rich in beta-glucans, a type of complex carbohydrate linked to immune-related research. But mushroom products, especially mycelium grown on grain, can also contain starch. Starch is a different kind of polysaccharide, called an alpha-glucan, and it comes from the grain substrate rather than the mushroom itself.

A testing method that measures “total polysaccharides” without separating alpha-glucans from beta-glucans will count starch as if it were beta-glucan. That inflates the number on the label without reflecting anything the mushroom actually produced. This is the single biggest reason lab results disagree across brands.

Common Testing Methods, Compared

• Enzymatic assay (Megazyme-type kits): Uses specific enzymes to break down and separately quantify alpha-glucans (like starch) and beta-glucans. This method can distinguish fungal beta-glucan from starch, which is why it’s widely used in mushroom research and by testing labs that specialize in fungal products.
• Generic total polysaccharide assays: Measure carbohydrate content as a whole, without separating starch from fungal beta-glucans. These tests are faster and cheaper, but they can produce inflated numbers for products that contain grain-based mycelium or added starches.
• FTIR (Fourier-transform infrared) spectroscopy: Identifies characteristic chemical bonds to confirm the presence and general structure of beta-glucans. It’s useful for confirming identity, but on its own it’s not always used to generate a precise percentage figure the way an enzymatic assay is.

None of these methods are “fake.” They’re built for different jobs. The problem is when a brand doesn’t say which method produced its number, because a strong-looking percentage from a generic polysaccharide test isn’t directly comparable to a percentage from an enzymatic assay.

Quick Comparison

• Enzymatic assay: Separates starch from beta-glucan — best for an accurate percentage.
• Generic polysaccharide test: Does not separate starch from beta-glucan — numbers can run high on grain-based mycelium products.
• FTIR: Confirms beta-glucan is present and gives structural information — less commonly used alone for a headline percentage.

What a Certificate of Analysis Can and Cannot Prove

A certificate of analysis, often shortened to COA, is a lab document showing test results for a specific sample. A real, dated COA from an independent lab can support a brand’s claim about that particular batch. But a COA has limits worth knowing before you treat it as a commitment:

• It reflects the sample that was tested, not necessarily every bottle on the shelf. Testing programs and batch-to-batch consistency vary by company.
• It only tells you what it was designed to test. A COA for heavy metals says nothing about beta-glucan content, and a beta-glucan number says nothing about which testing method produced it unless the method is stated.
• A dated, method-labeled COA from a named lab carries more weight than a generic “lab tested” claim with no document attached. If a page shows a testing badge or claim without a viewable, dated report, that claim can’t be verified from the outside.

The U.S. National Institute of Standards and Technology runs a Dietary Supplement Laboratory Quality Assurance Program specifically because measurement consistency across testing labs is a known industry challenge — reference materials and standardized methods exist precisely because results otherwise vary lab to lab.

A Simple Checklist for Reading a Beta-Glucan Claim

• Does the brand name the testing method (enzymatic assay, FTIR, or a generic polysaccharide test)?
• Is there an actual, dated COA available to view, not just a claim of “third-party tested”?
• Does the COA separate alpha-glucan (starch) from beta-glucan, or only report one combined number?
• Is the product a fruiting body extract or a mycelium-on-grain product? Grain-based mycelium is more likely to contain meaningful starch content.
• Is the testing lab named, and is it independent from the brand?

Evidence Limits

Published research on beta-glucans generally studies the compound itself, in controlled settings, rather than specific commercial products. A high beta-glucan percentage on a label reflects a chemical measurement, not a confirmed health outcome. Testing methodology explains why numbers differ between brands; it does not by itself tell you whether a given amount will produce a noticeable effect for any individual.

A Note for Certain Readers

Beta-glucans are studied for their interaction with immune activity. People with autoimmune conditions, people on immunosuppressive therapy, and people preparing for surgery should talk with a qualified healthcare provider before starting a mushroom supplement, since ingredient interactions with medications or existing conditions are outside the scope of a lab report.

Frequently Asked Questions

Does a “lab tested” label always mean the beta-glucan number is accurate?

Not necessarily. “Lab tested” tells you a test happened somewhere. It doesn’t tell you which method was used or whether the result separated beta-glucan from starch. Look for a viewable, dated report rather than the phrase alone.

What’s the real difference between alpha-glucan and beta-glucan on a report?

Alpha-glucans include starch, which mushrooms naturally contain only in small amounts but can be introduced through grain-based mycelium cultivation methods. Beta-glucans are the fungal cell-wall compounds most research focuses on. A report that separates the two gives a clearer picture than one combined “polysaccharide” figure.

Why do two competing products show very different beta-glucan percentages?

It can come down to the mushroom part used (fruiting body versus mycelium-on-grain), the extraction process, or, often, the testing method itself. A generic polysaccharide test and an enzymatic assay can yield very different values from the same starting material.

Can I verify a brand’s beta-glucan claim myself?

You can ask the brand for the actual COA, including the testing method and lab name, rather than relying on marketing copy. A brand confident in its testing should be able to provide this documentation on request.

Related Reading

• Mushrooms for Immune Support — how beta-glucans relate to immune modulation research across species.
• Maitake (Grifola frondosa) — a species profile covering beta-glucan and blood sugar research.
• Turkey Tail (Trametes versicolor) — covers PSK and PSP, two well-studied mushroom polysaccharide compounds.
• Our Research Standards & Disclosure — how this site sources and verifies the claims it publishes.

Educational Disclaimer

This article is for general education about supplement testing methodology and is not medical advice. It does not diagnose, treat, or evaluate the safety of any specific product. Always consult a qualified healthcare provider before starting any supplement, especially if you take medication or have an existing health condition.