Beta-Glucan Testing Explained

Beta-glucan figures appear on a growing number of mushroom products, sometimes as a headline selling point. Used well, they are genuinely informative. Used carelessly, they can mislead. This article explains how beta-glucans are measured, the difference between the main methods, what the numbers mean and how to read them critically.

Why measure beta-glucans?

Beta-glucans are a characteristic part of the fungal cell wall. Measuring them helps confirm that a product contains substantial fungal material, and, together with an alpha-glucan figure, can help distinguish fruiting body products from grain-heavy mycelium products.

“Polysaccharides” versus beta-glucans

Older and cheaper methods measure total polysaccharides: all the large carbohydrate molecules in a sample. A widely used colour test, developed in the 1950s, reacts with almost any sugar, producing a colour whose intensity reflects the total amount. It is quick and inexpensive, but not specific. That total includes beta-glucans, but also alpha-glucans such as starch, and other carbohydrates. For a product made from mycelium grown on grain, much of that total may simply be grain starch.

Enzyme-based methods

More specific methods use enzymes to break the sample down in controlled steps:

• Total glucans are measured by breaking all the glucose chains, alpha and beta, down to glucose with strong acid, then measuring the glucose released.
• Alpha-glucans are measured separately, using enzymes that digest only alpha-linked chains, such as starch and glycogen.
• Beta-glucans are calculated as the difference between the two.

Widely used commercial kits based on this approach are designed specifically for mushroom and yeast beta-glucans. Because they report alpha-glucans too, they also reveal how much starch a product contains. See Alpha-Glucans, Starch and What They Can Tell You.

Why methods give different answers

The same sample can give quite different beta-glucan figures depending on the method, and even between laboratories using the same method. Fungal beta-glucans are tightly bound to chitin in the cell wall, and how completely the sample is broken down affects the result. That is why a beta-glucan figure is most useful alongside its method, and why comparing figures from different brands, tested by different laboratories, needs care.

How results are expressed

For powders, results are usually given as a percentage of dry weight. For liquids such as tinctures, the figures depend on the concentration of the extract and can be expressed per millilitre or per serving, which makes them harder to compare with powders. Tinctures are also technically harder to test for beta-glucans, because the amounts per millilitre are smaller and the liquid needs preparing before analysis.

How to read a beta-glucan claim

• What method was used? A specific beta-glucan method, or total polysaccharides?
• Is the alpha-glucan figure given? A high alpha-glucan result suggests starch, often from grain.
• Which batch was tested, and when? Results apply to the batch tested.
• Was it the raw material or the finished product? Extraction and formulation change the numbers.
• Is a certificate available? See Certificates of Analysis.
• Is it per serving or per 100 g? A high percentage in a tiny serving may be a small amount.

What beta-glucan figures can’t tell you

A beta-glucan percentage says nothing about the structure of those beta-glucans, which varies between species and affects how they behave, nor about the other compounds in the mushroom, nor about what the product will do. No health claims are authorised for mushroom beta-glucans in the UK, and a higher number isn’t a promise of anything beyond more measured beta-glucan. (Some health claims are authorised for beta-glucans from oats and barley, which are different substances.)

Our approach

We don’t quote beta-glucan figures for our tinctures unless they are supported by testing of that product. If you’d like to know more about the testing behind our tinctures, get in touch.