Beta-Glucans and Mannans from Yeast – Invisible Helpers in Your Diet

1 | What's in the Yeast Cell Wall? Beta-Glucans and Mannans Explained

Yeasts like Saccharomyces cerevisiae (brewer's and baker's yeast) have a sturdy outer layer – the cell wall. It keeps the cell stable and protects it from external influences. Chemically, this cell wall mainly consists of two groups of polysaccharides:

• Mannans – long chains made of the simple sugar mannose
• Beta-Glucans – long chains made of the simple sugar glucose

These polysaccharides are linked in a way that our digestive enzymes in the small intestine cannot easily break them down. Therefore, like other soluble fibers, they are considered indigestible or hardly digestible and largely reach the large intestine unchanged.

There they encounter what is commonly called the microbiome: a diverse community of microorganisms that feed on the indigestible parts of our diet.

2 | Indigestible – but still interesting: Fiber, Microbiome & Short-Chain Fatty Acids

What is indigestible for us can be a welcome substrate for certain gut bacteria. Some bacteria specialize in metabolizing fiber and producing metabolic products – including short-chain fatty acids such as acetate, propionate, and butyrate.

In scientific literature, these short-chain fatty acids are discussed in connection with aspects such as:

• as an energy source for cells of the gut lining
• as a factor influencing the pH level in the gut
• as part of the complex interaction between diet, gut bacteria, and metabolic processes

Human studies on Mannan-Oligosaccharides (MOS) – short mannan chains from yeast – indicate that 2 g of MOS per day in healthy adults can be associated with changes in the microbiome and certain short-chain fatty acids. These findings are interesting but do not replace official health claims or individual medical advice.

In summary: Fiber – whether from oats, vegetables, or yeast cell walls – is a key part of a fiber-rich diet. Its effects depend on many factors, including overall eating habits, lifestyle, and individual circumstances.

3 | Mannans vs. Beta-Glucans – Structural Differences in Yeast Fibers

Although mannans and beta-glucans may look similar at first glance (both are polysaccharides), they differ in several ways:

• Sugar units:
  Mannans mainly consist of mannose units, beta-glucans of glucose units.
• Structure:
  Yeast beta-glucans typically appear as β-1,3/1,6-linked glucose chains. Mannans have different linkage patterns and may carry side chains.
• Occurrence:
  Both are found in yeast cell walls, but beta-glucans also occur in cereals like oats or barley. Cereal beta-glucans have a different structure than yeast beta-glucans.
• Health claim status:
  For oat and barley beta-glucans, the EU confirms: 3 g of beta-glucan from oats, oat bran, barley, or barley bran daily helps maintain normal blood cholesterol levels. This approved claim refers specifically to cereal beta-glucans and does not apply to yeast beta-glucans or mannans.

For yeast beta-glucans and mannans/MOS, there are currently no authorized health claims under EU regulations. Studies provide interesting insights but should not be interpreted as therapeutic or healing claims.

4 | Foods with Beta-Glucans and Mannans – Where to Find the Fiber

In everyday life, you can encounter beta-glucans and mannans in several places:

Food examples:

• Oat flakes and barley – contain cereal beta-glucans
• Guar gum – provides galactomannans (e.g., as a thickener in foods)
• Konjac products (e.g., konjac noodles) – contain glucomannan
• Nutritional yeast flakes – provide mannans and yeast beta-glucans

In supplements:

• Glucomannan capsules – a swelling fiber; always take with enough liquid to ensure they reach the stomach properly.
• MOS powder / yeast cell wall capsules – concentrated mannans and yeast beta-glucans from yeast cell walls.
• Yeast cell wall complexes like Makro-Immun – combine the natural matrix of the yeast cell wall (with beta-glucans and mannans) with micronutrients like vitamin C and zinc, which support normal immune function and help protect cells from oxidative stress.

Important: Even if products contain beta-glucans or mannans, you cannot automatically make health claims from this. It always depends on the authorized health claims for the specific nutrient.

5 | Research on Mannans and Beta-Glucans – What We Know Today

Mannans / MOS:

Clinical studies with Mannan-Oligosaccharides (MOS) from yeast investigate, for example, how 2 g MOS per day over several weeks affect selected microbiome parameters and short-chain fatty acid production in healthy adults. The results show indications of:

• changes in the amount of certain Bifidobacteria
• alterations in the profile of short-chain fatty acids

Such studies are scientifically interesting but usually involve small participant numbers and well-defined study conditions. They provide indications but no universal conclusions for everyone – and do not replace authorized health claims or individual medical advice.

Beta-Glucans:

For oat and barley beta-glucans, an authorized EU claim applies: 3 g of beta-glucan per day from oats, oat bran, barley, or barley bran contribute to maintaining normal blood cholesterol levels. This effect is considered within the context of a cholesterol-conscious diet.

For yeast beta-glucan, there are currently no recognized health claims. Research is ongoing, but no official health-related promises can currently be derived from the available data.

6 | Practical Tips: Integrating More Beta-Glucans and Mannans into Your Daily Life

If you want to include more fiber such as beta-glucans, mannans, and other polysaccharides in your diet, some simple rules can help:

• Increase gradually: If fiber intake is increased suddenly, the gut may initially react with bloating or changes in stool. Gradual increases give the body time to adjust.
• Drink enough fluids: Especially with swelling fibers (e.g., glucomannan), fluid is important to ensure they reach the stomach and are transported properly.
• Ensure variety: Oats in the morning, vegetables and legumes at lunch, possibly yeast products or yeast cell wall complexes later in the day – this exposes your gut to different types of fiber.
• Be patient: Changes in digestive comfort or stool may appear, if at all, over weeks rather than days. Not everyone perceives fiber in the same way.

7 | From Barn to Plate – Beta-Glucans and Mannans in Animal Nutrition

Mannan-oligosaccharides and beta-glucans have long been used in animal nutrition – for example, in feed for poultry or piglets. The goal is to supplement feed and support the interaction between feeding and the animals’ gut flora.

This shows that the basic principle – fiber as “food” for microorganisms – applies not only to humans. However, results from animal nutrition cannot be directly transferred to humans. They are rather one piece of the bigger puzzle of “diet and the microbiome.”

8 | Beta-Glucans and Mannans in Makro-Immun – Yeast Cell Wall Complex with Vitamin C and Zinc

If you want to specifically include yeast cell wall fibers in your diet, you can consider specialized products in addition to regular foods. An example is our yeast cell wall complex Makro-Immun.

Here we use a complete yeast cell wall matrix from brewer's yeast, naturally containing beta-glucans and mannans, combined with vitamin C and zinc. Vitamin C and zinc support normal immune function and help protect cells from oxidative stress. The beta-glucans and mannans serve as nutritionally interesting fiber components – without their own authorized health claims.

Depending on your personal needs and dietary habits, you can decide whether to obtain beta-glucans and mannans mainly through foods, yeast products, or combinations with micronutrients.

9 | Conclusion – Beta-Glucans and Mannans as Part of a Fiber-Rich Diet

Beta-glucans and mannans from yeast cell walls belong to the large family of dietary fibers. They are chemically well-defined, barely digested in the small intestine, and can serve as a “substrate” for parts of your microbiome in the large intestine. For certain types (like oat beta-glucan), authorized health claims exist; for yeast beta-glucan and MOS, the data are still emerging.

If you want to make your diet more fiber-rich and diverse, beta-glucans and mannans can be one piece of this puzzle – alongside whole grains, vegetables, legumes, nuts, and seeds. It is always important to keep the big picture in mind: diet, exercise, sleep, stress management, and – for health concerns – medical or nutritional advice.