# 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: 1. **"Beta-glucans" specified separately from "polysaccharides"** — if only "polysaccharides" is listed, the product may include alpha-glucans (starch) 2. **Fruiting body source** — fruiting bodies contain true beta-glucans; mycelium-on-grain contains mostly starch 3. **Extraction method** — hot water extraction is required to capture water-soluble beta-glucans 4. **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.*
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.