Beta-glucans
Summary
Beta-glucans are fibres whose effects depend on the source. Oat beta-glucan at 3 g a day or more lowers LDL cholesterol by about 0.25 mmol/L across 28 trials. Yeast beta-1,3/1,6-glucan is sold for immunity: trials found milder early cold symptoms but no fewer colds. Doses differ widely between the two.
Key facts
- Oat beta-glucan, taken in grams a day, is studied for cholesterol; yeast beta-1,3/1,6-glucan, taken in milligrams a day, is studied for colds and immune markers[1][3]
- 28 RCTs: oat beta-glucan ≥3 g/day lowered LDL by 0.25 mmol/L (about 10 mg/dL) and total cholesterol by 0.30 mmol/L; HDL and triglycerides unchanged[1]
- 900 mg/day for 16 weeks did not reduce the number of colds but eased physical symptoms in the first week[2]
- 250 mg/day for 90 days: 17 versus 28 colds, not statistically significant[3]
- 3 graded human outcomes on this page
- October 11, 2026
How it works
ProposedThe oat trials cited here measured cholesterol rather than mechanism; yeast beta-glucans are proposed to prime innate immune cells, based on changes in stimulated blood cytokines.[1][3]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Cold (URTI) incidence and symptom severity | Mixed | Grade C | RCT · n = 299 · 2019 Healthy adults with at least 3 colds in the previous year Form: Yeast beta-glucan · Dose: 900 mg/day · Duration: 16 weeks in winter Similar numbers got a cold (71 vs 70) and overall severity did not differ, but physical symptoms were milder over the first 7 days of an episode. | 30198828 (opens PubMed)Source [2] |
| Cold (URTI) incidence in older adults | No effect | Grade C | RCT · n = 98 · 2017 Adults aged 50–70 (49 completers per group) Form: Yeast beta-1,3/1,6-glucan (Wellmune) · Dose: 250 mg/day · Duration: 90 days in winter 17 confirmed colds versus 28 on placebo (odds ratio 0.55, not significant); symptom days trended lower and severity did not differ. | 28606567 (opens PubMed)Source [3] |
| Upper respiratory symptoms in stressed women | Improved | Grade D | RCT · n = 77 · 2012 Moderately stressed women Form: Yeast beta-glucan (Wellmune) · Dose: 250 mg/day · Duration: 12 weeks Fewer women reported upper respiratory symptoms (10% vs 29%) and mood and vigour scores were better than placebo. | 23378458 (opens PubMed)Source [4] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Oat or barley beta-glucan | Varies | No absorption data in the sources cited here. | No form-specific tolerance data in the sources cited here. | Cholesterol (3–12.4 g/day) |
| Yeast beta-1,3/1,6-glucan | Varies | No head-to-head human absorption data in the sources cited here. | Well tolerated at 250 mg/day for 90 days.[3] | Colds and immune markers (250–900 mg/day) |
Studied doses
Doses studied in human trials ranged from 250 mg to 900 mg of yeast beta-glucan per day for immune outcomes and from 3 g to 12.4 g of oat beta-glucan per day for cholesterol, for 2 to 16 weeks.[3][2][1]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- Choosing the wrong type
- The cholesterol evidence is for grams of oat beta-glucan; milligram yeast capsules are not studied for cholesterol.[1][3]
- Pregnancy and breastfeeding
- Supplement doses were not studied in the trials cited here.[3]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Where to buy Beta-glucans
Products from brands we partner with that contain Beta-glucans. Listing a product is not a claim that it works; check the amount per serving against the doses studied above, and the label for other ingredients.
- SupersmartPaid linkBeta 1.3/1.6 Glucan1 capsule: 250 mg yeast (Saccharomyces cerevisiae) extract standardized to 70% beta-1,3/1,6-glucans; 60 servings. That is about 175 mg of beta-glucan, a little under the 250 mg/day used in the yeast cold trials, and not a cholesterol product: the oat trials used 3 g or more.Shop at Supersmart (opens in new tab)Price and label checked 2026-10-11 on the brand’s site.
Partner links may earn us a commission. Learn more
Get 15% off with SMART026 (opens in new tab)15% off with code SMART026
Partner links may earn us a commission. Learn more
- Supersmart’s own terms and exclusions apply at checkout.
- 20% applies when 3 or more products ship on auto-delivery to the same address.
- The code discount and Subscribe & Save are separate offers; we don’t claim they combine.
- Offer terms from Supersmart’s site and its affiliate program, checked Oct 8, 2026. Offers can change; the brand's checkout is final.
Frequently asked questions
Do beta-glucans lower cholesterol?
Oat beta-glucan at 3 g a day or more lowers LDL by about 0.25 mmol/L (about 10 mg/dL); this does not apply to milligram yeast capsules.[1]
Do beta-glucans mean fewer colds?
Not clearly: yeast beta-glucan did not reduce the number of colds in two trials, though symptoms were milder early in one.[2][3]
How much oat beta-glucan is needed?
Trials showing lower cholesterol used at least 3 g a day.[1]
Sources
- [1]Cholesterol-lowering effects of oat β-glucan: a meta-analysis of randomized controlled trials. Am J Clin Nutr, 2014. meta-analysis
- [2]Effects of Yeast (1,3)-(1,6)-Beta-Glucan on Severity of Upper Respiratory Tract Infections: A Double-Blind, Randomized, Placebo-Controlled Study in Healthy Subjects. J Am Coll Nutr, 2019. RCT
- [3]Yeast-derived β-1,3/1,6 glucan, upper respiratory tract infection and innate immunity in older adults. Nutrition, 2017. RCT
- [4]Baker's yeast beta-glucan supplement reduces upper respiratory symptoms and improves mood state in stressed women. J Am Coll Nutr, 2012. RCT
What changed
- New monograph. Every PMID checked against NCBI E-utilities (title, journal and year from the PubMed record); each evidence row written from its abstract; intake and safety facts from the cited fact sheets.
- Review: evidence row id corrected to the first author; unsourced mechanism and absorption wording removed.