This 2021 rodent study investigated yeast cell wall β-glucan’s effects on the brain’s immune system:
“Innate immune memory can manifest in two different ways,  immune training and  immune tolerance, which means  an enhanced or  suppressed immune response towards a secondary challenge. Lipopolysaccharide (LPS) and β-glucan (BG) are two commonly used ligands to induce immune training and tolerance.
Microglia, the innate immune cells of the central nervous system, can adopt diverse phenotypes and functions in health and disease. In our previous study, we have shown that LPS preconditioning induces immune tolerance in microglia.
Compared to LPS, relatively little is known about effects of BG on microglia. In this study, we report for the first time that systemic administration of BG activates microglia in vivo, and that BG preconditioning induces immune training in microglia.
Our results show that BG activated microglia without inducing significant cytokine expression.
BG- and LPS-preconditioning both induced immune training in microglia two days after the first challenge. However, with an interval of 7 days between the first and second challenge, LPS-preconditioning induced immune tolerance in microglia where BG-induced immune training was no longer detected.”
https://jneuroinflammation.biomedcentral.com/articles/10.1186/s12974-021-02103-4 “Systemic administration of β-glucan induces immune training in microglia”
One solution to “BG-induced immune training was no longer detected” after 7 days is to take β-glucan every day. I haven’t seen studies that found β-glucan induced immune tolerance, i.e. “suppressed immune response towards a secondary challenge.”
I take allergy medicine twice a day. Switched over to a different β-glucan vendor and dose per Year One of Changing to a youthful phenotype with broccoli sprouts.
I take 1 gram of Glucan 300 capsules without eating anything an hour before or an hour afterwards. I’ve only been doing it for a week, though, and haven’t been able to separate out β-glucan effects on seasonal allergies. I’ll try stopping allergy medicine when pollen stops coating my car.
Swarming a spring sea trout run. Ospreys outcompeted gulls for breakfast.