Beta-glucans are naturally occurring long-chain carbohydrates known as polysaccharides, found in yeasts, fungi, bacteria and certain plants, including seaweed.1

Widely available as a dietary supplement, beta-glucans have received little fanfare compared to other more popular supplements, but there is reason to believe they may be useful for stimulating the immune system and warding off everything from infectious diseases to cancer.2

At the foundation of their benefits may be the ability to ramp up the innate immune system, a mechanism first suggested by Dr. Rolf Seljelid, professor emeritus at the University of Tromsø in Norway. In the 1980s, he noticed that sea urchins have a unique ability to survive, and thrive, in very polluted waters, including those contaminated with bacteria- and virus-ridden hospital runoff.

“It struck me that they must have some quality that keeps them from getting sick. Something we know nothing about,” Seljelid told Science Norway. Part of his life’s work became uncovering what that “something” was, and it turned out to be beta-glucans.3

Beta-Glucans Protect Against Infection, Cancer

Seljelid’s early research revealed that a certain type of beta-glucan known as beta-1,3 / 1,6-glucan may be beneficial for the innate immune system, which is your first line defense made up of natural killer (NK) cells, macrophages and white blood cells like neutrophils.

He and colleagues conducted a study on mice, which found that those injected with beta-glucan were not affected by a dangerous bacterial infection, while animals that didn’t receive beta-glucan died. Beta-glucan doesn’t have antibacterial properties, so it was suspected that it may work by making the body’s immune system stronger and more able to fight off the infection.

This led Seljelid to suspect it might be useful in cancer, too, and his early research again yielded impressive results. When mice with cancerous tumors received beta-glucan intravenously, their tumors disappeared.4 “After only six hours, the tumors had begun to collapse in many of the mice given beta-glucan. Fourteen days later, the tumors were gone,” Seljelid told Science Norway.5

In fact, beta-glucans have been used as a cancer treatment in Japan since 1980, and according to a 2007 report in Medicina, beta-glucans can prevent oncogenesis — the process in which healthy cells become cancer cells — by protecting against carcinogens that damage cellular DNA.6

Beta-glucans also help reduce inflammation associated with cancer and fight against metastasis, cancer recurrence and tumor drug resistance.7 Decades later, the Memorial Sloan Kettering Cancer Center in New York is conducting research into the combination of beta-glucans and cancer vaccines to treat children with severe neuroblastoma.

While only 40% to 50% of neuroblastoma patients typically live for five years after conventional treatments, those who received the beta-glucan along with the cancer vaccine had much higher survival rates.

“They have been working for years with a vaccine, which has a limited effect. But with the combination of the vaccine plus beta-glucan, around 90% of children were alive after five years. It is absolutely sensational,” Seljelid said.8

The Memorial Sloan Kettering Cancer Center has even applied for a patent for beta-1,3 / 1,6-glucan for use with cancer and along with vaccines for influenza. In January 2020, a team of Italian researchers further noted that beta-glucans appear to have a promising potential in the control of cancer:9

“A main feature of β-glucans is their capacity to function as biological response modifiers, exerting regulatory effects on inflammation and shaping the effector functions of different innate and adaptive immunity cell populations. The potential to interfere with processes involved in the development or control of cancer makes β-glucans interesting candidates as adjuvants in antitumor therapies as well as in cancer prevention strategies.”

Beta-Glucans Ward Off Bacterial, Viral Disease

Professor Jan Raa, Professor Emeritus at the University of Tromsø, also discovered beta-glucans’ infection-fighting abilities via early research — and quite by accident. While conducting a study on the use of bacteria and fungi as farmed salmon feed, 18 tanks of fish ended up contaminated by Hitra disease, a bacterial infection that’s often fatal to salmon.

Three of the tanks weren’t being used in the study, however, and Raa had mixed beta-glucan into their feed to see if it would have an effect on their health. It turned out that up to 90% of the salmon in non-beta-glucan tanks succumbed to Hitra disease, compared to only 20% of those fed beta-glucan. According to Science Norway:10

“Due to a coincidence and a catastrophic event, Raa had thus carried out a gigantic infection experiment which under normal circumstances, he would have never gotten permission to conduct. ‘I realized I had made a great discovery,’ he says. The incident resulted in several controlled infection trials that confirmed the observation, says Raa.”

Today, beta-glucans are widely used in animal feeds, including fish food pellets. Later work by Raa suggests that beta-glucan is also useful against viral infections like influenza. “[S]tudies we conducted at the Norwegian Institute of Public Health, which showed that beta-1,3 / 1,6-glucan led to a sharp increase in T cells that protect very effectively against influenza virus,” Raa said.11

This prompted both Raa and Seljelid to recently contact the Norwegian Institute of Public Health to suggest researching whether beta-glucan could prevent COVID-19. Raa is also involved in a study in partnership with the EU looking at whether beta-glucan can ward off flu and COVID-19 in a nursing home setting.

Could Beta-Glucans Fight COVID-19?

In an August 2020 study published in Science of the Total Environment, researchers suggested beta-glucans may protect you from SARS-CoV-2, the virus that causes COVID-19.12 One of the major complications of COVID-19 is pneumonia, which is sometimes accompanied by rapid replication of the virus.

During this rapid replication, your immune system releases proinflammatory cytokines that lead to an overreaction of the immune response called a cytokine storm. Cytokine storm can lead to lung injury, acute respiratory distress syndrome (ARDS) and death.

In this study, researchers took beta-glucans extract from a form of shiitake mushroom called Lentinus edodes and combined it with a lung injury model in vitro. They found that beta-glucans reduced interleukin-1 beta and interleukin-6, two cytokines that can trigger the cytokine storm that causes ARDS in severe COVID-19 cases.

The beta-glucans also reduced oxidative stress and activated immune substances called macrophages that destroy potential invaders like viruses. The researchers concluded, “Further clinical studies are merited to refine β-glucan as a countermeasure for tackling cytokine storm that causes ARDS, as evident with COVID-19.”13

In separate research published in Frontiers in Immunology on July 14, 2020, researchers also suggested that beta-glucans could help to bolster immune response to defend against COVID-19, and wrote, “Ultimately, we hypothesize that the use of oral β-glucan in a prophylactic setting could be an effective way to boost immune responses and abrogate symptoms in COVID-19 …”14 Other research also supports beta-glucans’ role in fighting viral infections. For instance:

  • Marathon runners who took 250 milligrams (mg) of beta-glucans from brewer’s yeast for 28 days following a marathon were 37% less likely to contract a cold or flu symptoms compared to those taking a placebo.15
  • People who took 250 mg of beta-glucans per day for 90 days reported 43 fewer days with symptoms of upper respiratory tract infection compared to those taking a placebo.16
  • A 2013 study found that taking 900 mg of beta-glucans from brewer’s yeast for 16 weeks reduced the rate of cold infections by 25% and eased symptoms in those who got ill by 15%.17
  • A 2015 animal study found feeding mice beta-glucans for two weeks “significantly reduced the effects of influenza infection in total mortality,” likely by stimulating cellular and humoral immune reaction that led to a lower viral load.18

More Beta-Glucan Benefits

Aside from their anticancer and immune-stimulating effects, beta-glucans are thought to play a role in fat metabolism and may help support weight loss and optimal cholesterol levels.19 Beta-glucans may also help promote the growth of beneficial bacteria in your gut by acting like a prebiotic.

In one study, beta-glucans improved the growth rate of Lactobacillus plantarum in the gut in both unstressed and stressed conditions. Perhaps most importantly, beta-glucans were able to protect the probiotics from gastrointestinal stress caused by low pH, bile salts and digestive enzymes, increasing their survival rate as they traveled through the digestive system.20

Beta-glucans may even improve insulin resistance, as they’ve been shown to reduce post-meal glucose and insulin responses, improve insulin sensitivity in diabetic and nondiabetic individuals and help with glycemic control.21

Smaller amounts of beta-glucans may be required to achieve the same results compared to other types of soluble fiber known to affect insulin response. According to one group of researchers from the University of Toronto, “The fermentability of β-glucans and their ability to form highly viscous solutions in the human gut may constitute the basis of their health benefits.”22

How Do Beta-Glucans Work?

There’s still debate over why, and how, beta-glucans actually work, considering they’re not absorbed by the body. “The problem with beta-glucans,” Science Norway reported, “… is that the body does not absorb them. They just whiz through the digestive tract and come out on the other side. Measurements have shown that almost nothing of the substance enters the blood.”23 So how do they work?

It’s not entirely known, but, according to the report, “Some researchers believe that the substance can affect our immune system by stimulating immune cells in the intestinal wall, without actually being absorbed by the body. Recent research has shown that the lining of the intestine is a very important part of the immune system.”24

Raa also suggests that the type of beta-glucans matter, with not all of them having a therapeutic effect. “For years, I have tried to explain to skeptics that there is only a certain chemical structure that works, namely one called beta-1,3 / 1,6-glucan. This is the one that is ‘recognized’ by animals and plants as danger signals that trigger immunological defense reactions,” he said.25

If you’re interested in exploring more, beta-glucan is widely available as a dietary supplement. You can also find beta-glucans in foods such as mushrooms (reishi, shiitake, maitake), baker’s yeast and seaweed.


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