Yeast beta-glucan (1,3/1,6)
Insoluble, particulate baker's yeast (Saccharomyces cerevisiae) beta-1,3/1,6-glucan — Wellmune WGP style. Buy the insoluble form specifically: the head-to-head trial found the soluble version did nothing. Not oat or barley beta-glucan, which is a different molecule for cholesterol.
Early
First results, or a theory about how it works
Kept at emerging despite a large pooled OR. The trials are small, heterogeneity is high, and essentially the entire literature is funded by the ingredient manufacturer — a pattern that reliably inflates effect sizes. The Mah trial is the most useful result precisely because it was internally controlled and showed one form working and the other not.
Across 13 studies people were much less likely to catch a cold, though the studies differed a lot from one another.
Pooled across 13 RCTs, odds of a URTI fell about 65% (OR 0.345, 95% CI 0.192–0.620) with fewer episodes (SMD −0.315, 95% CI −0.500 to −0.130), though heterogeneity was high.
Particulate beta-glucan is taken up by gut M cells and trafficked to bone marrow, where it primes neutrophils and monocytes via Dectin-1 and CR3 — 'trained immunity'. Primed cells kill opsonised pathogens faster without raising baseline inflammation, which is why it does not blunt the training response.
Endurance athletes in heavy blocks and anyone in a sustained open-window state — the evidence base is built almost entirely on marathoners and intense-exercise cohorts. Weakest case in sedentary, low-exposure users.
What to buy
- ✓Insoluble, particulate baker's yeast (Saccharomyces cerevisiae) beta-1,3/1,6-glucan — Wellmune WGP style. Buy the insoluble form specifically: the head-to-head trial found the soluble version did nothing. Not oat or barley beta-glucan, which is a different molecule for cholesterol.
- ✓250 mg/day of insoluble yeast beta-glucan, taken continuously. The marathon trial dosed for 45 days before the event and 45 days after.
- ✓Third-party tested (USP, NSF, Informed Sport)
- ✕Proprietary blends that hide the dose per ingredient
- ✕Unstandardised extracts with no active-compound percentage
As an Amazon Associate, Umbral earns from qualifying purchases. Product data is provided by Amazon and may change; ratings and prices shown are Amazon’s, not Umbral’s. Recommendations are based on the evidence grade and the form used in trials, never on commission.
Baker's yeast beta-1,3/1,6-glucan, which is the molecule with the immune data. Oat and barley beta-glucan is a different compound sold for cholesterol — it will not do this job.
Buy on Amazon
The best-reviewed of the three. Look for the insoluble, particulate form specifically — in the head-to-head trial the soluble version did nothing.
Buy on Amazon
A higher-dose option if you want to run above the 250 mg/day used in the Wellmune trials.
Buy on AmazonPrefer to compare yourself? This opens Amazon’s full selection for this supplement, filtered to the form we recommend.
See all on AmazonEvery result, next to the line that means no effect
Each diamond is a study's best estimate. The thin line shows how sure the study was: the shorter the line, the more certain the result.
- Number of URTI episodesSMD · Zhong 2021, Eur J Nutr−0.32−0.50 … −0.13
- URTI durationSMD · Zhong 2021, Eur J Nutr−0.31−0.56 … −0.06
- URTI incidence% odds · Zhong 2021, Eur J Nutr, 13 RCTs−65.0−81 … −38
Each unit gets its own scale, so numbers are never mixed on one line. When a study gave no range, we leave it blank instead of inventing one.
3 studies over 1 years
The studies
- 1.Effects of yeast β-glucans for the prevention and treatment of upper respiratory tract infection in healthy subjects: a systematic review and meta-analysisEuropean Journal of Nutrition · 2021 · rct · 13 experiments
URTI incidence OR 0.345 (95% CI 0.192–0.620, p<0.001); episodes SMD −0.315 (−0.500 to −0.130); duration SMD −0.312 (−0.561 to −0.064). High heterogeneity; no serious adverse events.
- 2.Soluble and Insoluble Yeast β-Glucan Differentially Affect Upper Respiratory Tract Infection in Marathon Runners: A Double-Blind, Randomized Placebo-Controlled TrialJournal of Medicinal Food · 2020 · rct · 1 experiments · n = 278
250 mg/day for 45 days pre- and post-marathon. Insoluble beta-glucan significantly lowered total URTI severity and symptomatic days vs placebo; soluble beta-glucan did neither. Both lowered nasal discharge severity; only insoluble lowered sore throat.
- 3.Beverage Containing Dispersible Yeast β-Glucan Decreases Cold/Flu Symptomatic Days After Intense Exercise: A Randomized Controlled TrialJournal of Dietary Supplements · 2020 · rct · 1 experiments
Reported a reduction in cold and flu symptomatic days after intense exercise with a dispersible yeast beta-glucan beverage. Numeric effect sizes could not be verified from an open-access source — treat the direction as supportive, not as a quantified estimate.
Umbral is a wellness product, not a medical device. It does not diagnose, treat, cure or prevent any disease. Supplement information is educational; talk to a clinician before starting anything, especially if you are pregnant, under 18, managing a condition or taking medication.
These statements have not been evaluated by the Food and Drug Administration.