Supplement
WGP Beta-Glucan
Immune support; reduces incidence and duration of upper respiratory tract infections; supports innate immune activation.
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
This is a fiber taken from baker's yeast. It is sold to support the immune system. Some studies found fewer or shorter colds and flu-like illnesses. But the larger studies did not meet the main goal they set out to test. So the evidence for fewer colds is mixed.
A letter describes the human evidence, not the product, the manufacturer, or the ingredient's worth.
See the full evidence record →Who responds: this record's trial reading reports no subgroup that identifies who responds.
Beta-1,3/1,6-D-Glucan · Whole Glucan Particle
Upper respiratory infections with yeast beta-1,3/1,6-glucan; the larger trials missed their registered primary outcomes.
Retail products state a beta-glucan milligram figure without naming the preparation. Evidence for the ingredient class does not transfer to a particular product, which is why this record refuses to state one studied dose.
A grade describes the intervention that was tested. Where the product on the shelf differs from it, this says so.
How this letter has changed · latest: October 2026 · Downgraded
An outside audit of October 2026 read the trials in full. The larger trials were null on their registered primary outcomes: Dharsono et al. (2019; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 30198828) on global severity, Fuller et al. (2017; PMID 28606567) on confirmed infections, and Mah et al. (2020; PMID 30380356) on the number and duration of episodes. The positive results are per-protocol or secondary, and the pooled analysis (Zhong et al., 2021; PMID 33900466) reports high heterogeneity How much the results of the pooled trials differ from each other. High heterogeneity makes a combined estimate less reliable.. Grade B needs at least one well-designed trial showing a meaningful effect; C covers small trials and mixed results.PMID 30198828 PMID 28606567 PMID 30380356 PMID 33900466
The dose field named a single daily dose and described the studied range as 250 to 500 mg. No cited trial used 500 mg, and the range was wrong in both directions. The baker's yeast beta-1,3/1,6-glucan trials used 250 mg per day; the insoluble brewers' yeast preparation trials used 900 mg per day. The field now states that there is no single studied dose, names each preparation with its own dose and duration, and records that the two preparations are not interchangeable.PMID 23378458 PMID 28606567 PMID 23340963 PMID 30198828
Every change to a letter on this site is dated and published. The full evidence log →
Commercial disclosure
EBL earns no commission on any supplement it grades. A purchase made through the dispensary link below pays EBL nothing, the practitioner discount goes to you in full. The dispensary is Fullscript, a practitioner dispensary, and many of the professional-grade brands in it are sold mainly through practitioners rather than in health food stores. Grades are assigned by published rubric before any commercial relationship exists and are never influenced by one. Full disclosure.
Two different preparations sit behind the trials on this page, not one. The 250mg trials used Wellmune, a baker's yeast beta-1,3/1,6-glucan from Saccharomyces cerevisiae. The 900mg trials used an insoluble brewers'/yeast preparation. Wellmune and WGP are trade marks held by other parties. Evidence generated with one preparation at one dose does not transfer to another preparation at another dose. Oat beta-glucan is a separate molecule with different evidence: its effect on LDL Low-density lipoprotein cholesterol, the cholesterol fraction most closely tied to plaque in the arteries. cholesterol is graded on its own record. Generic "beta glucan" supplements may not match either form. The source organism and particle form differ between products and between trials.
No single studied dose. Two preparations were tested at different doses and are not interchangeable. Baker's yeast beta-1,3/1,6-glucan (Wellmune, Saccharomyces cerevisiae): 250 mg/day, 12 weeks (PMID 23378458) and 90 days (PMID 28606567). Insoluble brewers'/yeast beta-1,3/1,6-glucan preparation: 900 mg/day, 16 weeks (PMID 23340963, PMID 30198828).
Food, particularly fat, may reduce absorption of the whole glucan particle. The cited trials gave a once-daily dose and did not test timing against a comparator, so no timing claim is supported by the evidence on this page.
In the 900 mg trial, the two daily capsules were taken at breakfast and at supper (PMID 23340963). The summaries of the 250 mg trials give one dose a day without a time (PMID 23378458, PMID 28606567).
Checked against the full report for 1 of the 3 cited studies, and the published summary for the rest. What the cited trials did, not a schedule. Every supplement, by trial timing →
Organ transplant on immunosuppressive therapy, and active autoimmune disease including rheumatoid arthritis, lupus, multiple sclerosis and inflammatory bowel disease. Beta-glucans are immune-activating by design, which is the point of the supplement and the reason for the contraindication.
Immunosuppressants and autoimmune biologics: mechanistically opposed. This is a mechanistic caution; no trial has measured the combination.
Mechanism-based, no human interaction study located. The drug interactions described for WGP Beta-1,3/1,6-D-Glucan are mechanism-based. A PubMed search for human interaction, pharmacokinetic or co-administration studies pairing it with immunosuppress, immunosuppressants returned no results in August 2026. The caution stands on pharmacology, not on a trial, and is labeled as such. Basis: pharmacological mechanism, not a human study. Searched PubMed in August 2026: 2 queries, 0 human results.
Incidence and duration of upper respiratory infections; subjective energy and recovery. No standard biomarker A measurable sign in the body, such as a blood test value, used to track a condition or the effect of a treatment. panel - immune tracking is clinical.
Primary evidenceSix papers, each linked to its PubMed record.
Four indexed randomized controlled trials People are assigned to the treatment or a comparison by chance, so the groups differ only in what they received. It is the design that can show cause and effect. of yeast beta-1,3/1,6-glucan for upper respiratory tract infection, with mixed results. Auinger 2013 (PMID 23340963, 900 mg/day, n=162): 25 percent fewer symptomatic common cold infections in the per-protocol population (p=0.041). Talbott 2012 (PMID 23378458, Wellmune 250 mg/day, n=77): reduced upper respiratory symptoms in stressed women. Fuller 2017 (PMID 28606567, Wellmune 250 mg/day, n=100): fewer confirmed infections (17 versus 28) but the difference was not statistically significant Unlikely to be explained by chance alone at the threshold the study set. It says nothing about whether the difference is large enough to matter. (p=0.149); symptom days showed a trend (p=0.067) and severity did not differ. Dharsono 2019 (PMID 30198828, 900 mg/day, n=299): the primary endpoint The one outcome a trial names in advance as its main test. Results on other outcomes carry less weight., global WURSS-21 severity, was not significant (p=0.5267); several secondary early-interval severity analyses were. Mah et al. (J Diet Suppl, 2020; PMID 30380356), 357 marathon runners on 250 mg/day for 91 days: the number and duration of URTI episodes did not differ; fewer symptom days only in the per-protocol analysis. Grade C: the registered primary outcomes of the larger trials were null, and the positive findings come from per-protocol and secondary analyses, so no well-designed trial shows a meaningful effect on its primary outcome. Pooled evidence: Zhong et al. (European Journal of Nutrition, 2021; PMID 33900466): systematic review A review that searches for every study on a question using a method set in advance, then assesses them together. and meta-analysis A study that pools the numbers from several trials into one combined estimate. of 13 randomized trials in healthy subjects, incidence of upper respiratory tract infection OR 0.345 (95% CI 0.192 to 0.620), with fewer episodes and shorter duration. The authors state that high heterogeneity and the small number of trials mean more high-quality research is warranted, which is exactly why this record states no single studied dose.
Auinger et al. 2013 (PMID 23340963): multicenter double-blind RCT Randomized controlled trial: people are assigned to the treatment or a comparison by chance, so the groups differ only in what they received. It is the design that can show cause and effect., n=162, insoluble yeast preparation 900mg/day for 16 weeks. Symptomatic common cold infections fell 25 percent in the per-protocol population (p=0.041). Talbott and Talbott 2012 (PMID 23378458): 77 stressed women, 250mg Wellmune WGP, 12 weeks, upper respiratory symptoms reduced from 29% to 10% in the treatment group. Fuller et al. 2017 (PMID 28606567): 90-day double-blind RCT, n=100, adults aged 50 to 70, Wellmune 250mg/day. Confirmed infections were 17 versus 28 on placebo An inactive substitute made to look like the real treatment, so participants cannot tell which one they received., but the difference was not statistically significant (p=0.149). Symptom days showed a trend (p=0.067) and severity did not differ. Dharsono et al. 2019 (PMID 30198828): double-blind RCT, n=299, 900mg/day for 16 weeks. The primary endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score., global WURSS-21 severity, was not significant (p=0.5267); several secondary analyses of early-interval physical symptom severity were. BWH Labs NCT07104929 trial registered on ClinicalTrials.gov, pending publication; will be reviewed for grade update upon publication.
The infection trials do not agree. The larger ones were null on their registered primary outcomes: global severity in Dharsono et al. (2019; PMID 30198828), confirmed infections in Fuller et al. (2017; PMID 28606567), and the number and duration of episodes in Mah et al. (2020; PMID 30380356). The positive results come from per-protocol and secondary analyses, and the pooled analysis (Zhong et al., 2021; PMID 33900466) reports high heterogeneity. Grade B needs at least one well-designed trial showing a meaningful effect on its own primary outcome, backed by more; small trials and mixed results are Grade C. The immune biomarker findings (natural killer cells, neutrophils, monocytes) describe the mechanism and carry no grade of their own. Moved from B to C in October 2026 after an outside audit read the trials in full.
Strong plausibility · Does not raise the Grade C
Beta-1,3/1,6-glucans are among the most studied natural compounds for inducing trained immunity, a recognized process in which innate immune cells undergo functional reprogramming after exposure to certain microbial signals. Unlike adaptive immunity, this does not create antigen-specific memory, but it may improve the speed and coordination of later innate responses. Laboratory and animal research links beta-glucans to changes in immune cell metabolism, gene expression, and epigenetic programming. EBL treats this as strong biological plausibility. It does not raise the EBL grade.
Trained immunity is now an accepted area of immunology and offers a credible explanation for why beta-glucans may affect immune function. A credible mechanism is not the same as proven benefit. EBL reserves higher grades for interventions supported by consistent, independently replicated The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away. human randomized controlled trials with clinically meaningful endpoints such as fewer or shorter infections, fewer sick days, lower hospitalization, or better vaccine response. Foundational mechanism papers on trained immunity, including the review articles that named the concept, strengthen plausibility but do not change the grade. This is why an EBL grade can sit below what a product's marketing implies.
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These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. The grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Starting, stopping or changing any supplement or medication is a decision for your physician.
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How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
("beta-glucan"[tiab] OR "beta glucan"[tiab] OR "β-glucan"[tiab] OR Wellmune[tiab] OR Yestimun[tiab]) AND yeast[tiab] AND (respiratory[tiab] OR cold[tiab] OR URTI[tiab] OR infection*[tiab]) AND (randomized controlled trial[pt] OR meta-analysis[pt])Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →