What Exactly Is Beta-Glucan & What Are Its Notable Health Benefits?

There's a lot of buzz around fiber, but it isn't a singular nutrient. While all fibers are types of carbohydrates, there are several varieties. One example is beta-glucans—bioactive plant compounds that have been linked to gut, heart, and immune health.

Beta-glucans are a type of fiber found in the cell walls of certain yeasts, bacteria, fungi, algae (like seaweed), along with other plants like oats, barley, wheat, rye, and mushrooms. Beta-glucans serve as a source of energy and structure in these various plant species.

Most grain-based beta-glucans are soluble fibers, which means they dissolve in water and are typically fermentable (i.e., prebiotic) in your digestive tract. Beta-glucans from bacteria, fungi, and yeast are typically insoluble in water.

Kristin Gillespie, M.S., R.D., L.D., CNSC, explains that improved heart health is likely the most well-known benefit of beta-glucans.

"Studies have identified improvements in total and LDL cholesterol levels with beta-glucan intake; these lipids are among the top risk factors for heart disease," she says. "The FDA has actually designated a heart-health claim for foods that are rich in beta-glucan based on this evidence." 

Linda Quinn, M.D., FAARM, calls beta-glucans "one of the most powerful immune-supporting phytochemicals." The research indicates that these bioactive polysaccharides can positively affect your immune system in a few unique ways.

In a comprehensive 2020 review published in Molecular Nutrition and Food Research, researchers examined the immune-support role of a specific type of beta-glucans5 (beta-1,3/1,6-glucans) from baker's yeast (Saccharomyces cerevisiae) in preclinical and human studies to date. 

The science demonstrates that beta-glucans have antioxidant properties and are potent immunomodulators: They help train and strengthen the innate defense functions of key immune cells like neutrophils and macrophages. These essential white blood cells help protect you from immunologic threats and infection.

Because certain beta-glucans (e.g., from oats and barley) are soluble fibers, they absorb water throughout the intestinal tract and bulk up stools, helping to promote regularity by improving constipation and diarrhea.

Beta-glucans also act as prebiotics7, feeding the good bacteria in your gut and helping balance your gut microbiome.

Like other soluble fibers, beta-glucans can have positive effects on a key metabolic health parameter: your blood sugar.

While most of the studies on beta-glucans and aging or life span have been conducted in animal models, longevity is another potential benefit worth mentioning.

Again, the evidence is in its early, exploratory stages, but in one study published in Rejuvenation Research12 in 2020, researchers found that beta-glucans exerted anti-aging effects on fish by promoting antioxidant activity, reducing oxidative stress, and helping fight off infection.

While many of the benefits of beta-glucans come from consuming them, there may be some benefit to putting it on your skin, too. In addition to its ability to permeate skin, potential mechanisms that make beta-glucans an excellent cosmetic candidate13 include its antioxidant, anti-wrinkle, and moisturizing properties.

"Aside from consuming a bowl of oatmeal as we generally think of it, you can add oats to smoothies, protein shakes, or baked goods to increase your beta-glucan intake," recommends Gillespie. "Oat flour can be utilized in place of regular flour in baking. Barley is also rich in beta-glucan; consider utilizing pearl barley in place of other starchy side dishes, such as rice."

Quinn recommends combining different sources of beta-glucans, or "bundling it for the boost," so you can benefit from the synergy of plant phytochemicals. 

Fiber supplements are an alternative option for those worried about getting enough beta-glucans from their diet. It's a good idea to speak with your healthcare practitioner before taking it as a supplement. For example, those on blood pressure medications should be especially careful, since beta-glucans can cause your blood pressure to drop too low.

The ideal dosage of supplemental beta-glucan remains unclear. There is a daily dose range of 100-500mg that has been tested in human studies for immune system stimulation15, compared to the suggested dose of 3 grams for lowering blood pressure.

Though there isn't an established upper limit on overall daily fiber intake, health experts recommend women consume at least 25 grams a day (28-29 if breastfeeding) and men consume at least 38 grams daily. The average American doesn't get enough fiber—only around 16 grams16 per day.

Beta-glucans work in different ways depending on the health benefit17 you're talking about. For immune health, beta-glucans are antioxidant immunomodulators that help train our innate immune defenses and balance inflammatory responses.

For gut health18 and cardiometabolic benefits (i.e., lowering cholesterol3 and improving glycemic control11) from oats and barley, the biological mechanism is rooted in the fact that they're soluble fibers. This means beta-glucans pull in water from the gut and form a viscous, gel-like substance, slowing down the transit of foods (and absorption of their components, like glucose and cholesterol) through your digestive tract.

There's a lot of existing foundational science and future promise surrounding the health benefits of beta-glucans. Supplementation research using beta-glucan concentrate or extracts is an active area of growing research, especially for immune health, in children and adults.

Beta-glucans are very well tolerated and have a strong record of safety. In clinical studies using beta-glucans from oats or barley, no adverse side effects19 have been observed in children or adults. And the same safety has been shown across the life span for beta-glucan extracts from yeast, too.

One potential drug-nutrient interaction to mention is immunosuppressants. Because beta-glucans promote and stimulate the immune system, a person on immunosuppressant drugs should discuss any plans to significantly increase their beta-glucan intake with their health care practitioner.