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What Are Beta-Glucans? Complete Guide for Supplement Buyers

Beta-glucans are the primary active compounds in functional mushroom supplements. Here's what they do, how much you need, and how to verify quality.

Published 2025-01-05 · Updated 2026-06-01 · 8 min read

The short answer

Beta-glucans are polysaccharides found in the cell walls of fungi that activate the immune system by binding to Dectin-1 receptors on immune cells. They are the primary active compounds in functional mushroom supplements. Quality mushroom extracts contain 20–40% beta-glucan content by weight, verified by third-party COA. Products listing only "polysaccharides" may contain mostly inactive starch. Cogniscore requires beta-glucan-specific COA verification for a Transparency score above 7/10.

25%+

Beta-glucan content required for Cogniscore quality rating (lion's mane)

Cogniscore methodology

Dectin-1

Receptor through which mushroom beta-glucans activate immune cells

Brown & Gordon, Nature, 2001

3×

More beta-glucans in fruiting body vs. mycelium-on-grain

Bak et al., 2014

27%

Of lion's mane products tested showed less beta-glucan than labelled

Cogniscore 2026

What Are Beta-Glucans?

Beta-glucans (β-glucans) are a family of naturally occurring polysaccharides—complex carbohydrates—found in the cell walls of fungi, yeast, oats, and barley. In functional mushroom supplements, the relevant beta-glucans are (1→3),(1→6)-β-D-glucans, which have a distinctive branching structure that the human immune system recognises and responds to.

Unlike simple carbohydrates, beta-glucans are not digested in the small intestine. They reach the gut intact, where they are recognised by pattern-recognition receptors—particularly Dectin-1—on immune cells lining the gut. This triggers a cascade of immune activity: macrophages become more active, natural killer (NK) cells are primed, and the overall immune response is modulated.

Why Beta-Glucan % Matters for Supplement Quality

When you see "polysaccharide content" on a mushroom supplement label, this number includes all polysaccharides—including inactive starches from grain substrates used in mycelium-on-grain products. A product listing "40% polysaccharides" may contain only 5% actual beta-glucans, with the rest being grain starch.

Quality mushroom supplement brands disclose their beta-glucan content specifically, verified by a third-party lab using the Megazyme assay. Cogniscore's scoring system requires this specific disclosure for a Transparency score above 7.0/10.

Beta-Glucan Targets by Mushroom Species

Mushroom	Minimum Beta-Glucan %	Other Key Compounds	Primary Use
Lion's Mane	25%+	Hericenones (fruiting body cap)	Cognitive / NGF support
Reishi	20%+	Triterpenes / Ganoderic acids (4%+)	Stress / Immune / Sleep
Chaga	20%+	Betulinic acid (wild-harvested only)	Antioxidant / Immune
Turkey Tail	30%+	PSK/PSP polysaccharides	Immune modulation
Cordyceps	25%+	Cordycepin (0.3%+)	Energy / ATP / VO₂ max
Tremella	20%+	Large hydrating polysaccharides	Skin hydration

How to Read a Supplement Label for Beta-Glucans

Look for "beta-glucan %" specifically. If you only see "polysaccharides," the brand is not disclosing beta-glucan content—a transparency red flag.
Check the source. "Fruiting body" indicates higher beta-glucan potential. "Mycelium," "mycelium biomass," or "full spectrum" suggests mycelium-on-grain.
Find the COA. The best brands publish a Certificate of Analysis from a third-party lab. Look for the Megazyme assay result showing beta-glucan content and starch content separately.
Check starch content. Quality fruiting body extracts have less than 5% starch. Mycelium-on-grain products often show 30–60% starch in COA testing.

Cogniscore's Beta-Glucan Verification Methodology

Cogniscore verifies beta-glucan claims by reviewing the Certificate of Analysis submitted by brands or obtained from independent lab testing. In our 2026 review of 140+ functional mushroom products, 27% showed lower beta-glucan content in COA results than stated on the label.

Brands that provide verifiable COAs showing beta-glucan content at or above their label claim, tested by an ISO 17025-accredited laboratory, receive Cogniscore's "Verified" transparency badge and score significantly higher on the Transparency dimension (30% of total score).

Beta-Glucan Questions Answered

What are beta-glucans in mushroom supplements?+

Beta-glucans are a class of soluble dietary fibre—specifically polysaccharides—found in the cell walls of fungi, oats, barley, and yeast. In mushroom supplements, beta-glucans (primarily (1→3),(1→6)-β-D-glucans) are the primary immunomodulatory compounds. They activate immune cells (macrophages, NK cells, dendritic cells) by binding to Dectin-1 receptors, triggering innate immune responses.

How much beta-glucan should a lion's mane supplement have?+

Cogniscore recommends a minimum of 25% beta-glucan content by weight in a lion's mane fruiting body extract. Many products list 'polysaccharides' rather than 'beta-glucans'—polysaccharides include both active beta-glucans and inactive starches, so the number is always higher. Always look for a beta-glucan-specific test result on the COA, not just total polysaccharides.

What is the difference between beta-glucans and polysaccharides?+

Polysaccharides is a broad category of complex carbohydrates that includes beta-glucans, alpha-glucans (starches), and many others. Beta-glucans are a specific subset of polysaccharides with a distinctive (1→3)(1→6) branching structure that gives them their immune-activating properties. When a brand lists only 'polysaccharide content,' the number includes starch—so it's not a reliable indicator of potency. Always ask for beta-glucan content specifically.

Do all mushrooms have the same amount of beta-glucans?+

No. Beta-glucan content varies significantly by species and by production method. Turkey tail (Trametes versicolor) typically has the highest beta-glucan yield (30–40% in quality extracts). Reishi and chaga follow at 20–35%. Lion's mane and cordyceps typically yield 20–30% in quality fruiting body extracts. Mycelium-on-grain products of any species typically test below 10%, often below 5%.

How do I verify beta-glucan content in a supplement?+

Request or review the Certificate of Analysis (COA) from the brand. A legitimate COA will show beta-glucan content as a percentage, tested by an accredited third-party laboratory (look for ISO 17025 accreditation). The test method should be the Megazyme assay or equivalent—the most widely accepted method for beta-glucan quantification.

What is the clinical reference dose for beta-glucans?+

Clinical dose references vary by purpose. For immune support, studies use 3–15 mg/kg/day of beta-glucans. For a 70 kg adult, that's 210–1,050 mg/day of pure beta-glucans. A 500 mg capsule of 30% beta-glucan extract provides 150 mg—so 1–3 capsules per day covers the lower end of clinical dosing.

Are oat beta-glucans the same as mushroom beta-glucans?+

No. Oat beta-glucans are primarily (1→3),(1→4)-β-D-glucans, which are well-studied for cardiovascular and cholesterol benefits. Mushroom beta-glucans are (1→3),(1→6)-β-D-glucans, which have a different branching structure that specifically activates the Dectin-1 immune pathway. They are related but functionally distinct.

Sources

Brown GD & Gordon S (2001). Immune recognition of fungal beta-glucans. Nature. Link
Bak et al. (2014). Beta-glucan content in Hericium erinaceus fruiting body vs mycelium. Journal of Agricultural and Food Chemistry. PubMed
Volman JJ et al. (2008). Dietary modulation of immune function by beta-glucans. Physiology & Behavior.
Consumer Labs (2022). Mushroom Supplement Review — independent beta-glucan testing.
Cogniscore Brand Database (2026). Internal COA verification across 140+ products.

Information on this platform relates to nutritional composition and public disclosure practices only. It is not medical advice. No claims are made about the therapeutic efficacy, safety, or suitability of any product. Always consult a qualified healthcare professional before taking any supplement.