What are beta-glucans?
Beta-glucans are a type of fiber found in the cell walls of cereals, algae, bacteria, and fungi. Their natural functions range from glucose storage to cellular and whole-plant structural integrity and to cell protection. Beta-glucans can be taken as a supplement or consumed as part of the diet, with the richest dietary sources being oats, barley, oyster mushrooms, and shiitake mushrooms.[2]
All beta-glucans consist of chains of glucose molecules linked via β-glycosidic bonds, but the chain length, branching, and types of β-linkages can vary, leading to differences in biological activity and physical characteristics. For example, cereal beta-glucans are soluble, consisting of unbranched chains of glucose units linked with a mixture of β-(1,3) and β-(1,4) bonds. On the other hand, fungal beta-glucans can be soluble or insoluble, and their glucose units are linked with β-(1,3) bonds, with or without branches attached via β-(1,6) bonds. While beta-glucans from oats and barley demonstrate some favorable effects on metabolic health, beta-glucans from yeasts and mushrooms are better known for their immune-modulating properties.[5]
What are beta-glucans’ main benefits?
The beta-glucans found in cereals are the most thoroughly researched type, and their benefits appear similar to other kinds of soluble dietary fiber.
In people with dyslipidemia, beta-glucans from oats or barley may provide small reductions in LDL cholesterol and total cholesterol.[6][7][8] These beta-glucans also promote satiety and are linked to a small degree of weight loss.[9]
When included in a carbohydrate-containing meal, beta-glucans from oats and barley may lower the postmeal increase in blood glucose and insulin.[9] Although reductions in fasting blood glucose and hemoglobin A1c (HbA1c) have been reported in people with type 2 diabetes, these effects have tended to be small enough that their clinical relevance is questionable.[10]
What are beta-glucans’ main drawbacks?
Cereal and fungal beta-glucans taken orally are generally reported to be safe and well tolerated, and most research has not identified any major side effects associated with the use of beta-glucans.[11] Possible side effects are generally gastrointestinal, including diarrhea, constipation, nausea, flatulence, or abdominal cramping.[12]
Due to the immune-stimulating properties of fungal beta-glucans, use in people with an autoimmune disease should warrant caution. Although this hasn’t been explored in clinical research, it’s theoretically possible that fungal beta-glucans could worsen autoimmunity.
There’s a lack of research looking at whether beta-glucans are safe during pregnancy. It’s probably safe to assume that exposure to beta-glucans through food poses no harm.
How do beta-glucans work?
The metabolic effects of oat and barley beta-glucans are largely due to their physical properties as soluble, viscous dietary fibers. These beta-glucans can hold onto water, creating a gel-like consistency in the gastrointestinal tract. This can have many effects, including slower gastric emptying, reduced digestion and absorption of glucose, and enhanced elimination of bile acids (which can have the downstream effect of lowering cholesterol).[13]
Fungal beta-glucans from yeast or mushrooms may produce immune-modulating effects by binding to pattern recognition receptors on immune cells in the gastrointestinal tract. This can lead to the initiation of an immune response by the innate immune system, which might include the activation of macrophages, neutrophils, and natural killer cells. Still, changes in the levels of immune cells or the compounds they produce (e.g., cytokines) are not consistently found.[2][5]
Lastly, interactions between beta-glucans and the gut microbiome may contribute to the effects of beta-glucans, in terms of both their metabolic effects and their immune-modulating effects. Preclinical research suggests that beta-glucans may have prebiotic properties, meaning they could promote the growth of beneficial microorganisms in the gut which may provide health benefits to the body. However, there’s currently no clinical research connecting the benefits of beta-glucans to microbiome modulation.[14]
What are other names for Beta-glucans
- β-glucans
- Beta-D-glucans
- Oat beta-glucans
- Barley beta-glucans
- Yeast beta-glucans
Dosage information
Beta-glucans usually come as a powder that may be loose or in capsules. Oat and barley beta-glucans generally require larger doses, which is more easily achieved with a loose powder that can be added to food or beverages.
For lowering cholesterol, taking oat or barley beta-glucans orally at a dosage of at least 3 grams daily is recommended.[1] If choosing to supplement with whole foods, this can also be achieved with about 75 grams (2.6 ounces) of whole grain oats, 55 grams (2 ounces) of oat bran, or 45 grams (1.6 ounces) of barley.[2]
For lowering postmeal increases in blood glucose and insulin levels, adding around 3 grams (0.1 ounce) of oat beta-glucans per 30 grams (1 ounce) of carbohydrates seems to be effective.[3]
For reducing the incidence and duration of upper respiratory tract infections, taking yeast beta-glucans orally at a dosage of 250 mg daily for at least 4 weeks may be effective.[4]
Research FeedRead all studies
In this exploratory randomized controlled trial in Japanese adults, eating cooked waxy barley (containing beta-glucans) was more effective than eating white rice for preventing upper respiratory tract infection symptoms and improving mood status.
Frequently asked questions
Beta-glucans are a type of fiber found in the cell walls of cereals, algae, bacteria, and fungi. Their natural functions range from glucose storage to cellular and whole-plant structural integrity and to cell protection. Beta-glucans can be taken as a supplement or consumed as part of the diet, with the richest dietary sources being oats, barley, oyster mushrooms, and shiitake mushrooms.[2]
All beta-glucans consist of chains of glucose molecules linked via β-glycosidic bonds, but the chain length, branching, and types of β-linkages can vary, leading to differences in biological activity and physical characteristics. For example, cereal beta-glucans are soluble, consisting of unbranched chains of glucose units linked with a mixture of β-(1,3) and β-(1,4) bonds. On the other hand, fungal beta-glucans can be soluble or insoluble, and their glucose units are linked with β-(1,3) bonds, with or without branches attached via β-(1,6) bonds. While beta-glucans from oats and barley demonstrate some favorable effects on metabolic health, beta-glucans from yeasts and mushrooms are better known for their immune-modulating properties.[5]
The beta-glucans found in cereals are the most thoroughly researched type, and their benefits appear similar to other kinds of soluble dietary fiber.
In people with dyslipidemia, beta-glucans from oats or barley may provide small reductions in LDL cholesterol and total cholesterol.[6][7][8] These beta-glucans also promote satiety and are linked to a small degree of weight loss.[9]
When included in a carbohydrate-containing meal, beta-glucans from oats and barley may lower the postmeal increase in blood glucose and insulin.[9] Although reductions in fasting blood glucose and hemoglobin A1c (HbA1c) have been reported in people with type 2 diabetes, these effects have tended to be small enough that their clinical relevance is questionable.[10]
Beta-glucans are found on the surface of potentially pathogenic microorganisms like bacteria or yeasts, which means the presence of these beta-glucans in the body can signal to the immune system that a pathogen is present and it’s time to mount an immune response. When fungal beta-glucans are supplemented directly, the same effect may be achieved without the infective pathogen. Accordingly, preliminary research has tended to report that fungal beta-glucans may enhance immune function, which could be useful in a variety of contexts.
Fungal beta-glucans may bolster the body’s ability to fight infection. Yeast beta-glucans have been reported to reduce the incidence, duration, and symptoms of upper respiratory tract infections (URTIs) in both children and adults, as well as in athletes who may be prone to exercise-induced immune suppression. However, most of these studies have been industry funded, which has the potential to introduce bias.[4]
These immune-stimulating properties may also be useful in the context of wound healing. While supported by in vitro and animal research, only a few clinical trials have examined this effect, and only one has been a randomized controlled trial.[15] This limited research suggests that cream containing 2–3% yeast beta-glucans might promote the healing of stubborn wounds, like venous ulcers or diabetic ulcers.[16][17][18][19]
Lastly, fungal beta-glucans may have a role as an adjuvant to chemotherapy for cancer treatment. In China and Japan, there are prescription-grade beta-glucans specifically formulated for intravenous use that appear to be effective as an adjuvant to chemotherapy, improving response rates, quality of life, and 1-year survival.[5] Research looking at whether oral beta-glucans provide the same effect is limited. Some noncontrolled studies have reported improvements in immune function and quality of life, but the evidence is weak and more research is needed.[20][21]
Cereal and fungal beta-glucans taken orally are generally reported to be safe and well tolerated, and most research has not identified any major side effects associated with the use of beta-glucans.[11] Possible side effects are generally gastrointestinal, including diarrhea, constipation, nausea, flatulence, or abdominal cramping.[12]
Due to the immune-stimulating properties of fungal beta-glucans, use in people with an autoimmune disease should warrant caution. Although this hasn’t been explored in clinical research, it’s theoretically possible that fungal beta-glucans could worsen autoimmunity.
There’s a lack of research looking at whether beta-glucans are safe during pregnancy. It’s probably safe to assume that exposure to beta-glucans through food poses no harm.
The metabolic effects of oat and barley beta-glucans are largely due to their physical properties as soluble, viscous dietary fibers. These beta-glucans can hold onto water, creating a gel-like consistency in the gastrointestinal tract. This can have many effects, including slower gastric emptying, reduced digestion and absorption of glucose, and enhanced elimination of bile acids (which can have the downstream effect of lowering cholesterol).[13]
Fungal beta-glucans from yeast or mushrooms may produce immune-modulating effects by binding to pattern recognition receptors on immune cells in the gastrointestinal tract. This can lead to the initiation of an immune response by the innate immune system, which might include the activation of macrophages, neutrophils, and natural killer cells. Still, changes in the levels of immune cells or the compounds they produce (e.g., cytokines) are not consistently found.[2][5]
Lastly, interactions between beta-glucans and the gut microbiome may contribute to the effects of beta-glucans, in terms of both their metabolic effects and their immune-modulating effects. Preclinical research suggests that beta-glucans may have prebiotic properties, meaning they could promote the growth of beneficial microorganisms in the gut which may provide health benefits to the body. However, there’s currently no clinical research connecting the benefits of beta-glucans to microbiome modulation.[14]
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References
Examine Database References
- Upper Respiratory Tract Infection Risk - Zhong K, Liu Z, Lu Y, Xu XEffects of yeast β-glucans for the prevention and treatment of upper respiratory tract infection in healthy subjects: a systematic review and meta-analysis.Eur J Nutr.(2021 Dec)
- Fasting Glucose - Zou Y, Liao D, Huang H, Li T, Chi HA systematic review and meta-analysis of beta-glucan consumption on glycemic control in hypercholesterolemic individuals.Int J Food Sci Nutr.(2015)
- Apolipoprotein B - Hoang V T Ho, John L Sievenpiper, Andreea Zurbau, Sonia Blanco Mejia, Elena Jovanovski, Fei Au-Yeung, Alexandra L Jenkins, Vladimir VuksanThe effect of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for CVD risk reduction: a systematic review and meta-analysis of randomised-controlled trialsBr J Nutr.(2016 Oct)
- Low-density lipoprotein (LDL) - de Morais Junior AC, Schincaglia RM, Viana RB, Armet AM, Prado CM, Walter J, Mota JFThe separate effects of whole oats and isolated beta-glucan on lipid profile: A systematic review and meta-analysis of randomized controlled trials.Clin Nutr ESPEN.(2023 Feb)
- Fasting Glucose - Shen XL, Zhao T, Zhou Y, Shi X, Zou Y, Zhao GEffect of Oat β-Glucan Intake on Glycaemic Control and Insulin Sensitivity of Diabetic Patients: A Meta-Analysis of Randomized Controlled Trials.Nutrients.(2016 Jan 13)
- Insulin - Zurbau A, Noronha JC, Khan TA, Sievenpiper JL, Wolever TMSThe effect of oat β-glucan on postprandial blood glucose and insulin responses: a systematic review and meta-analysis.Eur J Clin Nutr.(2021 Nov)
- Weight - Rahmani J, Miri A, Černevičiūtė R, Thompson J, de Souza NN, Sultana R, Kord Varkaneh H, Mousavi SM, Hekmatdoost AEffects of cereal beta-glucan consumption on body weight, body mass index, waist circumference and total energy intake: A meta-analysis of randomized controlled trials.Complement Ther Med.(2019 Apr)