Beta-Glucan: What Lies Behind the Dietary Fibre

Beta-glucan is a collective term for a group of natural dietary fibres found in cereals, yeast and mushrooms. The term keeps coming up especially in connection with oats, barley and medicinal mushrooms, and many promises circulate around the topic of the immune system. In this guide we objectively put into context what beta-glucans are, which sources they are found in, what forms exist, what European legislation actually allows you to say, and what you should look out for when it comes to intake, purchase and safety. This way you can better separate advertising claims from provable facts.

What is beta-glucan?

Beta-glucans are long-chain sugar molecules, more precisely polysaccharides, made up of many interconnected glucose units. The prefix beta refers to the type of chemical linkage, which humans cannot break down with their own enzymes. That is why beta-glucans are among the dietary fibres that reach the large intestine undigested.

It is important to note that beta-glucan is not the same as beta-glucan. The exact structure differs significantly depending on the source. Beta-glucans from oats and barley are built differently from those from yeast or from mushrooms. These structural differences are significant because the properties and the legal assessment differ depending on the origin. Anyone who talks about beta-glucan should therefore always keep the source in mind.

Specifically, it is about the way the individual glucose building blocks are linked to one another. In oats and barley there are different linkage patterns than in the beta-glucans from yeast and mushroom cell walls. Solubility also differs: the cereal beta-glucans are readily water-soluble and form viscous solutions in the digestive tract, while many mushroom and yeast beta-glucans are less soluble. These seemingly technical details explain why statements about one source cannot simply be transferred to another.

Occurrence and forms

Beta-glucans occur in several natural sources that differ in structure and use:

• Oats and barley: the most important cereal sources, containing soluble beta-glucans.
• Yeast: baker's and brewer's yeast provide beta-glucans with a different structure.
• Mushrooms: edible and medicinal mushrooms such as reishi, shiitake or oyster mushrooms contain mushroom-typical beta-glucans.

In the shops you will find beta-glucans both in foods, such as in oat flakes and oat bran, and in concentrated form as powder, capsules or extracts. For extracts from yeast or mushrooms, the beta-glucan content is sometimes given in standardised form. For a meaningful comparison it is therefore helpful to consider both the source and the stated content.

With cereals, the degree of processing also plays a role. Wholegrain oats and oat bran contain more beta-glucans than heavily processed products in which the outer, fibre-rich layers have been partly removed. Anyone who wants to specifically take in beta-glucans through their diet is therefore best served by cereal products that are as minimally processed as possible. With ready-made mixtures it is worth looking at the list of ingredients, because not every product that advertises oats also provides notable amounts of beta-glucans.

The approved EU claim for beta-glucans

For beta-glucans from oats and barley there are health claims examined by the European Union. One of them reads, in its exact wording: Beta-glucans contribute to the maintenance of normal blood cholesterol levels. This claim is tied to a daily intake of three grams of beta-glucans from oats, oat bran, barley or barley bran.

In addition, there is another approved claim, according to which the consumption of beta-glucans from oats or barley as part of a meal contributes to the reduction of the blood glucose rise after that meal. What is decisive: these claims apply expressly to beta-glucans from oats and barley. For beta-glucans from yeast or mushrooms, as well as for the frequently advertised topic of the immune system, there is no health claim approved by the EU. Corresponding advertising promises around the body's defences are not legally covered and should be viewed critically.

Intake and everyday life

How you sensibly incorporate beta-glucans into everyday life depends on the goal. Anyone orienting themselves by the cholesterol-related EU claim reaches the intended three grams a day, for example, through oat flakes, oat bran or barley products, spread over the day. A breakfast with oat flakes is a simple and everyday-friendly option here.

With concentrated supplements from yeast or mushrooms, you should stick to the manufacturer's instructions and not exceed the recommended amount. Since beta-glucans are dietary fibres, it makes sense to drink enough and to increase the amount slowly so that the digestion can get used to it. A suddenly very high fibre intake can otherwise lead to a feeling of fullness or flatulence.

For the cholesterol-related claim, regularity is also decisive. The three grams are intended as a daily amount over a longer period, not as a one-off portion. In practice this means firmly incorporating beta-glucan-rich foods into the meal plan, such as porridge in the morning and barley in soups or salads. Anyone who takes in cereal beta-glucans through natural foods benefits at the same time from the other accompanying substances of the whole grain, which can be an additional advantage over isolated supplements.

What you should look out for when buying

When comparing beta-glucan products, some criteria help you:

• Stated source: oats, barley, yeast or mushroom, because the structure and the legal assessment differ.
• Content statement: reputable extracts state the beta-glucan proportion as a percentage or in milligrams per portion.
• Purity testing: with mushroom and yeast extracts, analyses for heavy metals and microbial contamination are sensible.
• Transparent declaration: a clear list of ingredients without unnecessary additives.

Caution is advised with products that advertise unclear health promises around the immune system without specifically naming the source. A good product makes transparent statements about origin and content and refrains from non-approved claims.

Another point is the price-performance ratio. For the cholesterol-related claim, beta-glucans from oats and barley are intended, which can be taken in very cheaply through completely ordinary foods such as oat flakes or oat bran. An expensive extract is not necessary for this. Concentrated supplements from yeast or mushrooms are aimed more at people who want to specifically use these special sources. It is therefore worth clarifying before buying which goal you are actually pursuing, and then deciding between food and supplement.

Safety and tolerability

Beta-glucans from foods such as oats and barley are considered well tolerated and are part of a fibre-rich diet. With a greatly increased fibre intake, temporary digestive complaints can occur, which is why a slow increase and sufficient fluid are advisable.

For concentrated extracts from yeast or mushrooms, less extensive data is available. People with known allergies to yeast or mushrooms should avoid the corresponding products. For pregnant women, breastfeeding women and people with diseases of the immune system, a cautious approach is called for. Dietary supplements do not replace a varied and balanced diet and a healthy lifestyle. If you are unsure, take medication regularly or have health complaints, speak with your doctor before taking them.

Anyone trying beta-glucans in concentrated form for the first time should also pay attention to their own tolerability and start with a small amount. This allows you to observe calmly whether the product is well tolerated before the amount is slowly increased. When combining several fibre-rich supplements, too, it is advisable to keep an eye on the total amount so that the digestion is not overwhelmed.

Suitable products

Anyone interested in mushroom-typical beta-glucans quickly comes across traditionally used medicinal mushrooms. Our reishi extract from the lingzhi mushroom relies on a concentrated 20:1 extract with a defined proportion of bioactive polysaccharides and is manufactured in Germany. Reishi (Ganoderma lucidum) has been used traditionally for a long time in various cultures. The product sees itself as a supplement to a balanced diet and not as a replacement for plant-based variety.

Frequently asked questions (FAQ)

What is beta-glucan?

Beta-glucans are natural dietary fibres made of long-chain sugar molecules. They occur in oats, barley, yeast and mushrooms. Humans cannot break them down with their own enzymes, which is why they are among the dietary fibres.

What may you say about beta-glucans according to the EU?

Approved, among others, is: beta-glucans contribute to the maintenance of normal blood cholesterol levels. This claim applies to three grams of beta-glucans daily from oats or barley, not to yeast or mushroom sources.

Do beta-glucans help the immune system?

For beta-glucans there is no health claim approved by the EU regarding the immune system. Advertising statements around the body's defences are not legally covered and should be viewed critically.

How much beta-glucan is in oats?

Oats and oat bran are among the most important sources of soluble beta-glucans. For the cholesterol-related EU claim, three grams a day are intended, which can be reached through oat flakes or oat bran spread over the day.

Are beta-glucans well tolerated?

Beta-glucans from oats and barley are considered well tolerated. With a greatly increased fibre intake, temporary flatulence can occur, which is why a slow increase and sufficient fluid are sensible.