Functional mushrooms, including shiitake, maitake, turkey tail, and reishi, have a history of versatile health benefits spanning centuries. One reason these medicinal mushrooms can do everything from helping the immune system and digestive tract to improving heart health is thanks to one of their unique components called beta-glucans (also written β-glucans).
Beta-glucan is a soluble fiber located primarily in the cell walls of mushrooms and whole grains, known to lower blood sugar, defend against infections, and even kill cancer cells.
This article provides an in-depth look at the health power of beta-glucans in functional mushrooms, including how beta-glucans work, their many benefits, and their most bioavailable forms for diet incorporation.
Beta-glucans are a type of dietary fiber called polysaccharides that occur naturally in the cell walls of functional mushrooms and foods like oats, wheat, and barley. Polysaccharides are carbohydrate arrangements made of long simple sugar molecule chains. They support cells and tissues, provide energy storage, and offer powerful health benefits.
The body doesn’t produce beta-glucans, so people must obtain them through food like mushrooms and supplements.
β-glucan is a soluble fiber that dissolves in water and forms a thick, gel-like, indigestible substance. This polysaccharide travels through the gastrointestinal (GI) tract without the body breaking it down or absorbing it, allowing people to feel fuller, longer. As beta-glucans travel through the GI tract, they can carry excess lipids like cholesterol out with them. This process positively impacts metabolism, blood sugar, and cholesterol levels.
Beta-glucans also act as disease-fighting agents by triggering events that help regulate the immune system and make it function more efficiently. Specifically, beta glucans stimulate the activity of immune cells that ingest and demolish invading pathogens and energize other immune cells to attack.
Studies show beta glucan positively affects digestion, which can help reduce heart disease and cholesterol levels. Beta-glucans, particularly those in functional mushrooms, also stimulate the immune system, helping to fight bacteria, viruses, and tumors and prevent infections.
Beta-glucans play a vital role in the following body functions:
Human white blood cells have receptor sites on their surfaces that bind with polysaccharides like beta-glucan, like a lock on a door that needs the right key to open. When this happens, beta-glucans stimulate the white blood cells to latch onto tumors and viruses and release chemicals to destroy them.
Research shows beta-glucans help the immune system function optimally by:
Research indicates that beta-glucan promotes heart health and positively impacts the body in several ways that reduce heart risk:
Beta-glucans show significant potential in their cancer-fighting abilities. Studies show this soluble fiber can be a natural cancer treatment by stimulating the immune system to attack malignant cells, inhibiting tumor growth.
Most US-based research on beta-glucans’ cancer potential involves animal studies. However, other countries have performed human trials, reporting a positive impact on patient survival and quality of life.
Beta-glucans work as Biological Response Modifiers (BRMs), stimulating an increased immune response and enabling a more effective reaction for fighting off infections. Beta-glucans can also help the body battle antibiotic-resistant bacteria and viruses that cause upper respiratory infections.
An imbalance in gut bacteria can lead to an overgrowth of potentially harmful microorganisms and disrupt overall health. As a soluble fiber, β-glucan ferments in the lower digestive tract and balances the gut microbiome.
Mushrooms are an excellent source of beta glucans. But concentration of beta-glucans varies based on the species, growth environment, and mushroom maturity. Additionally, beta glucan molecules differ in structure from species to species, a significant factor in determining their bioactivity.
The wild-grown edible mushrooms below have some of the highest beta glucan content, according to this quantitative evaluation.
A different study looked at commercially cultivated mushrooms, which are more common on grocery store shelves. Specifically, researchers looked at different Agaricus bisporus (white button mushrooms), Lentinula edodes (Shiitake), Cantharella cibarius (chanterelle mushrooms), and Pleurotus ostreatus (oyster mushrooms).
Chanterelle had the highest overall beta glucan content combining its cap and stalk, followed by shiitake mushrooms. Oyster mushrooms came in third followed, and white button mushrooms came in last.
Maitake mushrooms don’t appear in these studies. Still, they’re known to contain beta-glucans with several branching side chains, increasing the likelihood the polysaccharides will reach and activate a greater number of immune cells. Lion’s Mane, Turkey Tail, and Reishi mushrooms also have notable beta glucan content.
Conversely, portobello mushrooms have some of commercial edible varieties' lowest beta glucan content.
In addition to medicinal mushrooms, beta-glucan occurs naturally in various food sources. Grains like barley and oats contain the highest concentration of beta-glucan. One and a half cups of cooked oatmeal or three packets of instant oatmeal provide three grams of beta-glucans, while one cup of cooked pearl barley contains approximately 2.5 grams of beta-glucans.
Beta-glucans also appear in many other foods, although to a lesser extent, including:
Beta-glucan is most abundant in raw foods because processing and cooking will reduce the beta-glucan content. Eating raw oats is virtually impossible, so consumers should look for whole grains as close to their natural states as possible. For example, steel-cut oats will have more polysaccharides than instant oatmeal. Additionally, oat flour and pearl barley are better than barley flour.
Consuming raw mushrooms also presents a bioavailability issue because mushroom cells contain chitin, a rigid and challenging-to-digest material. Cooking mushrooms is essential to break down the chitin, but this process also reduces the beta-glucan content. People can consume mushroom powders or capsules to avoid this heat-driven degradation.
Beta-glucan is a robust dietary fiber found in the cell walls of mushrooms and other foods that don’t break down in the digestive system. They slow digestion, helping to stabilize blood sugar and cholesterol levels and interact with immune cells. Scores of research show that adding beta-glucan to a daily diet—either in the form of supplements or foods containing the compound—can significantly help the body fend off everything from the common cold to heart disease and cancer.
Not all beta-glucan sources are created equal, so finding scientifically validated products is crucial. With the explosion of functional mushroom products, quality-tested varieties will rise above the competition.
ACS Laboratory tests functional mushroom products for purity with the same quality levels as our award-winning cannabis and hemp testing. Contact ACS to start testing mushroom products today.