Last fall, I was at a medical convention and my roommate came down with something mid-trip. She took a couple of capsules of a supplement she'd been using and then handed the bottle to me — just in case. I stayed healthy the whole trip. I paid attention.
I've since purchased it myself. And if you know me, you know I don't recommend things I haven't personally vetted.
The supplement is called beta-glucan. Since that convention, I've packed it on every trip, recommended it to patients, and watched it earn its place in my clinical toolkit. With spring colds making the rounds right now, it feels like exactly the right time to give you a proper breakdown of what it is, how it works, and who it's really for.
Beta-glucans are naturally occurring polysaccharides — complex carbohydrates — found in the cell walls of mushrooms, yeast, oats, barley, and certain bacteria. They've been studied for decades as immune modulators, but the research has really accelerated in recent years.
What makes beta-glucans interesting isn't just that they "boost" immunity in a vague, general way. It's how they work.
Beta-glucans interact with specific receptors on your immune cells — particularly something called Dectin-1, Toll-like receptors, and complement receptor 3. When those receptors are activated, they trigger a cascade that enhances the function of macrophages, dendritic cells, natural killer (NK) cells, and T-cells. These are the very immune cells I see get out of balance in my Long Covid clients.
But here's what really caught my attention: research shows they can induce what's called "trained immunity."
Trained immunity is a form of innate immune memory. Your immune cells undergo metabolic and epigenetic reprogramming — they essentially learn — so that the next time they encounter a threat, they respond more quickly and effectively. This isn't just a temporary boost. It's a meaningful shift in how your immune system operates.
Not all beta-glucans are the same, by the way. The source matters — cereal-derived beta-glucans have a different molecular structure than fungal or yeast-derived types, and that structure affects biological activity. Molecular weight, degree of branching, and solubility all influence how well they actually work.
This is why product quality and sourcing matter so much.
For colds and upper respiratory infections:
A systematic review of 34 randomized controlled trials found that fungal beta-glucans reduced both the incidence and symptoms of colds, flu, and upper respiratory infections — particularly in people who are prone to getting sick. If that's you, this is worth knowing about.
For Long COVID and chronic illness:
This is where I get especially excited for my patient community. Beta-glucans have been proposed as a tool for Long COVID recovery through their ability to modulate the chronic inflammatory responses that keep people stuck. A pilot clinical study in COVID-19 patients found that beta-glucans significantly decreased inflammatory markers including IL-6 and D-dimer compared to standard treatment alone. While specific Long COVID trial data is still emerging, the mechanism is compelling — and I've seen it support patients clinically.
For cancer support:
Beta-glucans are increasingly being studied as complementary agents in oncology. Recent clinical trials (2023–2025) showed improved survival outcomes in melanoma and lung cancer, alongside reduced chemotherapy toxicity. Researchers have also observed synergy with immunotherapy drugs, particularly in immunogenic tumors. This is a rapidly developing area worth watching.
Yes — and the data here is reassuring. A systematic review of randomized controlled trials found no adverse events causally related to beta-glucans across studies using doses ranging from 2.5 to 1,000mg daily for up to 6.5 months. The most commonly reported side effects are mild GI discomfort in roughly 10–15% of users and allergic reactions in about 2–5%.
Toxicity studies in rodents established a no-observed-adverse-effect level of 2,000mg/kg/day, with no mutagenicity detected.
Since that convention, beta-glucan has shown up in three consistent places in my life:
- Travel. It's in my bag every time I go somewhere. When you're in airports, sharing spaces with family, or attending conferences, your immune exposure goes up. This is my baseline protection.
- Acute illness. At the first sign of a scratchy throat or that 'uh oh' feeling, I increase the dose. I've watched family members bounce back quickly — faster than expected.
- Chronic immune support. For my Long COVID and my patients especially, it's become part of broader protocols. Not a standalone solution, but a meaningful piece of recovery.
In terms of dosing, I generally suggest somewhere in the 100–500mg daily range — lower end for maintenance and prevention, higher when you're actively fighting something or dealing with chronic immune challenges. That said, everyone's body is different, so please discuss dosing with your provider to find what's right for your specific situation.
The brand I personally trust is BWH Labs. I was given their product at that convention and have been buying it myself ever since. Given how much product quality varies in this space — and how much source and preparation method matter for efficacy — I feel good about recommending this one specifically.
Get it through Fullscript with a 15% discount using our link → LINK
- My Cold & Flu PDF — remedies, strategies, and tips for prevention and recovery, including how to use your mind to support immune function. Download your PDF here.
- My Fullscript Immune Collection — a curated list of researched supplements for respiratory and immune support, including specific probiotic strains with evidence behind them. LINK
Beta-glucan isn't hype. The research is real, the safety profile is excellent, and the mechanism — training your immune system to respond smarter — is genuinely exciting from a functional medicine perspective.
A note on timing: most springs I'm writing to you about allergy season. This spring I keep coming back to immune support — and there's a reason. COVID tends to resurface every summer, reliably enough at this point that it's worth planning for. Getting proactive now, while you're feeling well, is so much better than playing catch-up when something's already going around. This is a good time to stock your toolkit.
Whether you're trying to avoid the spring cold that's going around, supporting your body through Long COVID, or just want to be ready for whatever summer brings: this supplement is worth knowing about.
In Great Health,
Dr. Jenny Tufenkian, ND
Resources:
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