Alpha and Beta Glucans: Understanding the Polysaccharides of Functional Mushrooms
Beta-glucans are the primary bioactive compounds in functional mushrooms — but not all beta-glucans are equal. This guide explains the structural differences between alpha and beta glucans, how they are extracted, and what to look for in a quality mushroom polysaccharide supplement.
Alpha and Beta Glucans: Understanding the Polysaccharides of Functional Mushrooms
Polysaccharides — specifically beta-glucans — are the primary bioactive compounds in functional mushrooms and the key quality markers in standardised extracts. Yet the term "polysaccharides" on a supplement label can be misleading. This guide explains what beta-glucans are, how they differ from alpha-glucans, and why the distinction matters enormously for supplement quality.
What Are Glucans?
Glucans are polysaccharides (long chains of glucose molecules) that differ in how their glucose units are linked together. The type of linkage — specifically whether it is an alpha (α) or beta (β) glycosidic bond — determines the three-dimensional structure of the molecule and, critically, its biological properties.
Alpha-Glucans (α-Glucans)
Alpha-glucans have α-glycosidic bonds between glucose units. The most common alpha-glucans are:
- Starch — the storage polysaccharide in plants and grains
- Glycogen — the storage polysaccharide in animals and fungi
- Dextran — produced by bacteria
Alpha-glucans are easily digested by human enzymes (amylases) and are broken down into glucose for energy. They have no specific biological activity beyond nutrition.
The critical problem for mushroom supplements: Mycelium-on-grain products contain large amounts of starch (an alpha-glucan) from the grain substrate. When total polysaccharides are measured without distinguishing alpha from beta, the starch inflates the apparent polysaccharide content — making a low-quality product appear high in polysaccharides.
Beta-Glucans (β-Glucans)
Beta-glucans have β-glycosidic bonds between glucose units. This seemingly small structural difference creates a fundamentally different three-dimensional shape — a linear or branched chain that human digestive enzymes cannot break down. Beta-glucans are therefore not digested as energy but interact with the body in other ways.
The most important beta-glucans in functional mushrooms are:
- (1→3)-β-D-glucans — the primary backbone
- (1→6)-β-D-glucans — branching chains
- (1→3),(1→6)-β-D-glucans — the most common form in mushrooms, with a (1→3) backbone and (1→6) branches
The EFSA-Authorised Beta-Glucan Claim
The European Food Safety Authority (EFSA) has authorised one specific health claim for beta-glucans under EU Regulation 1924/2006:
"Beta-glucans contribute to the maintenance of normal blood cholesterol levels."
This claim is authorised specifically for oat and barley beta-glucans at a dose of ≥3g per day. It is not authorised for mushroom beta-glucans.
Mushroom beta-glucans have a different molecular structure from oat/barley beta-glucans and are the subject of ongoing research, but no EFSA-authorised health claims exist for mushroom-derived beta-glucans at this time.
Structural Differences Between Mushroom Beta-Glucan Species
| Mushroom | Primary Beta-Glucan | Unique Features |
|---|---|---|
| Turkey Tail | (1→3),(1→6)-β-D-glucan | PSK and PSP (protein-bound) |
| Maitake | (1→6)-β-D-glucan | D-Fraction (unique branching) |
| Shiitake | (1→3)-β-D-glucan | Lentinan (triple helix) |
| Reishi | (1→3),(1→6)-β-D-glucan | Protein-bound (GL-PS) |
| Agaricus Blazei | (1→3),(1→6)-β-D-glucan | Exceptionally high concentration |
| Chaga | (1→3)-β-D-glucan | Lower concentration vs. triterpenoids |
How to Read a Mushroom Supplement Label
When evaluating a mushroom supplement, look for:
- "Beta-glucans" specified separately from "polysaccharides" — if only "polysaccharides" is listed, the product may include alpha-glucans (starch)
- Fruiting body source — fruiting bodies contain true beta-glucans; mycelium-on-grain contains mostly starch
- Extraction method — hot water extraction is required to capture water-soluble beta-glucans
- Percentage standardisation — ≥20–30% beta-glucans is the quality benchmark for fruiting body extracts
The Nutera Alpha + Beta Glucan Formula
Nutera's Alpha + Beta Glucan 30ml combines extracts from multiple mushroom species to provide a broad-spectrum polysaccharide profile. The formula is standardised to ≥40% polysaccharides from fruiting body sources, with beta-glucan content verified by enzymatic assay (the Megazyme method — the gold standard for distinguishing beta-glucans from alpha-glucans/starch).
This article is for informational purposes only. Food supplements are not intended to diagnose, treat, cure, or prevent any disease.
— Products mentioned in this article
