How does yeast beta glucan help the immune system?

The immune health is crucial for staying healthy. A sound immune system is of great importance to cope with different diseases or illnesses. We all need to enhance our immune system. Regular exercise or taking some natural or artificial product directly or indirectly boosts the immune system.
Natural substances that improve the immune system are the subject of investigation for the last decades. A wide range of synthetic and natural products are available in the market described as having immunomodulatory effects. However, only a few products are probably the best studied, and interesting ones are β-glucans (Goodridge et al., 2009; Stier et al., 2014).

History of β-glucans as immune system modulator

Before identifying β-glucans as an immune modulator, shiitake mushroom (Lentinus edodes) in Japan and Ganoderma luciderm in China were used in traditional medicine, boosting the body immune system. The immune-modulating effect of β-glucan discovered in the last century.
Since more than 6000 publications have published investigating the immune-modulation effect of the β-glucans, such as antimicrobial and anti-inflammatory abilities, the β-glucans show immune-modulating effects on various organisms.
The results on humans and other animals like fish, rodents, invertebrates, and other farm animals are encouraging. Furthermore, other beneficial effects of β-glucans include healing wounds, hepatoprotective, antidiabetic, and cholesterol reduction (Novak & Vetvicka, 2008).

Importance of β-glucans in immune modulation

Various studies show that β-glucan have the potential to enhance the immune system. The majority of options exist in the market while choosing multiple products to boost the immune system, and β-glucan is one of those products. The β-glucan is water-soluble dietary fiber in the cell wall of yeast, fungi, bacteria, algae, lichens, and plants (barley, oat, seaweed).
However, the β-glucans from different sources have different modulating effects but not all. It depends upon the primary chemical structure of β-glucan. For example, cellulose a (1,4)- β-linked glucan does not have any immune-modulatory effect. While yeast and fungus-derived β-glucan, (1,3)-β-linked with small chains of (1,6)-β-linked side chains are known for their immune-modulating effect.
Besides the primary chemical structure, the immune-modulating effect of β-glucan also depends on its solubility, molecular mass, tertiary structure, polymer charge, branching pattern, solution conformation, and its manufacturing, from isolation to purification affect its immune modulation efficiency (Vannucci et al., 2013).

Various sources of β-glucans

Various β-glucans function in multiple ways based on their sources; for example, cereal-based beta-glucan reduces LDL-cholesterol, healing wounds, skin injury. Still, there is not enough scientific evidence that such kind of β-glucans enhances the immune system.
Mushroom-derived β-glucans are associated with lowering cholesterol levels, improving heart health, wound healing, and in some cases, strengthening the immune system to some extent.

Yeast β-glucan is found abundantly in the cell wall of baker’s yeast (Saccharomyces cerevisiae). The β-glucan is a water-soluble polysaccharide consist of glucose subunits.

The yeast-derived β-glucan, specifically the baker’s yeast Saccharomyces cerevisiae, is well-known for boosting immunity compared to brewer’s yeast. It means not all yeast strain-derived β-glucan are equally efficient. It also helps in the healing of wounds. For immune system modulation, the source from which β-glucan source is essential (Seo et al., 2019).

Mode of action β-glucans in immune system modulation

Interaction between Immune cells and β-glucans

The human gastrointestinal tract is a vital immune organ enriched with dendritic cells and macrophages immune cells. Thus, anything passing through the gastrointestinal tract immune cells recognizes it. These immune cells contain specialized pattern-recognition receptors (PRRs) recognizing and responding to any structure related to harmful microbes.

Adaptive immunity

With the β-glucan ingestion, cell surface immune receptors, PRRs consider it a foreign substance and directly bind. Then, the binding between these two alert the immune cells and induce a series of biochemical reactions, which renders the immune system behave effectively. So, the innate immune system is a complex signaling network of germ-line encoded pattern-recognition receptors (PRRs). The immune cells or other cells usually express to induce various cell signaling pathways. Thus it activates a wide range of signaling pathways. Mainly, it has physiological effects and modulates the immune system. These signaling pathways are related to a group of compounds responsible for physiological effects. Finally, β-glucans help the immune system to react effectively against harmful microorganisms during infection. Thus, β-glucans ensure safety and overall health benefits. Consequently, β-D-glucan triggers innate immune responses and develop adaptive immunity (Murphy et al., 2010; Novak & Vetvicka, 2008).

Yeast β-glucan is versatile in developing an adaptive immune system.

Initially, the yeast β-glucan triggered the interleukin-1β-(1L-1β) mediated cell signaling responses primarily through macrophages via dectin-1 signaling. Yeast β-glucan stimulates the effect on macrophages and shows strong immune modulation effects. Additionally, the yeast β-glucan interacts with microfold (M)-cells in the small intestine. Then, the M-cells take β-glucan and transport it to the immune cells present in Peyer’s patches from the intestine lumen. Finally, macrophages take up the yeast β-glucan, and it gets degraded. Eventually, it became available to the circulatory system and distributed systemically. Thus, yeast β-glucan are potential activators of the innate immune system that enhance the functional activity of immune cells. Finally, it activates the network of cell signaling pathways, which systemically develop adaptive immune responses against diseases (Murphy et al., 2010; Novak & Vetvicka, 2008).

Why choose yeast β-glucans for immune-modulatory effects?

While selecting the best and high-quality β-glucan, which is safe and effective in modulating the immune system, we need to consider some important points. Yeast β-glucan biological activity, mechanism of action, the chemical structure is well studied, and immune system functioning and supported by research.
Yeast-derived β-glucans prime the immune system to perform efficiently instead of boosting it. It enables the immune system to recognize the foreign pathogen. It recognizes the microbial pathogens and phagocytizes the infective cells and limit the further spread of disease. Yeast-derived β-glucan is equally effective for all ages of people, from children to old age. It is also effective in stress release in athletes and women passing through stress and improves overall physical health (Seo et al., 2019; Stier et al., 2014; Talbott & Talbott, 2012).

Reference

Goodridge, H. S., Wolf, A. J., & Underhill, D. M. (2009). Beta-glucan recognition by the innate immune system. Immunological Reviews, 230(1), 38–50. https://doi.org/10.1111/j.1600-065X.2009.00793.x
Murphy, E. A., Davis, J. M., & Carmichael, M. D. (2010). Immune modulating effects of β-glucan. Current Opinion in Clinical Nutrition and Metabolic Care, 13(6), 656–661. https://doi.org/10.1097/MCO.0b013e32833f1afb
Novak, M., & Vetvicka, V. (2008). β-Glucans, History, and the Present: Immunomodulatory Aspects and Mechanisms of Action. Journal of Immunotoxicology, 5(1), 47–57. https://doi.org/10.1080/15476910802019045
Seo, G., Hyun, C., Choi, S., Kim, Y. M., & Cho, M. (2019). The wound healing effect of four types of beta-glucan. Applied Biological Chemistry, 62(1), 20. https://doi.org/10.1186/s13765-019-0428-2
Stier, H., Ebbeskotte, V., & Gruenwald, J. (2014). Immune-modulatory effects of dietary Yeast Beta-1,3/1,6-D-glucan. Nutrition Journal, 13, 38. https://doi.org/10.1186/1475-2891-13-38
Talbott, S. M., & Talbott, J. A. (2012). Baker’s Yeast Beta-Glucan Supplement Reduces Upper Respiratory Symptoms and Improves Mood State in Stressed Women. Journal of the American College of Nutrition, 31(4), 295–300. https://doi.org/10.1080/07315724.2012.10720441
Vannucci, L., Krizan, J., Sima, P., Stakheev, D., Caja, F., Rajsiglova, L., Horak, V., & Saieh, M. (2013). Immunostimulatory properties and antitumor activities of glucans. International Journal of Oncology, 43(2), 357–364. https://doi.org/10.3892/ijo.2013.1974