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Oat and Barley Beta-Glucan (soluble fibre)
The viscous soluble fibre in oats and barley. About 3 g a day, mostly eaten in foods, lowers LDL cholesterol by about 0.2 to 0.27 mmol/L in several meta-analyses, but how well it works depends on the product, and a trial of beta-glucan tablets found no effect.
What the evidence says
Oat Beta-Glucan appears to help in 3 of 3 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 2010–2026 with a typical study size of 661 participants.
Based on 9 studies · 7 meta-analyses · 2 RCTs · 10,661 total participants
Confidence
High confidenceWhat the studies found
By outcome
Moderate 6.5: several meta-analyses of oat and barley trials agree that about 3 g a day of beta-glucan lowers LDL cholesterol by about 0.2 to 0.27 mmol/L (around 5%), without changing HDL or triglycerides. It is held below Strong because the effect is modest, heterogeneity between trials is high, it depends on the molecular weight and viscosity of the product, the one trial of beta-glucan tablets found no effect at any dose, and no trial has measured cardiovascular events.
Beta-glucan is the main soluble fibre in oats and barley. It forms a viscous solution in the gut, and eaten at about 3 g a day it lowers LDL cholesterol.
Meta-analyses agree on the direction and size: 3 g or more a day of oat beta-glucan lowered LDL by 0.25 mmol/L across 28 trials, a median 3.5 g a day lowered it by 0.19 mmol/L across 58 trials, and barley beta-glucan lowered it by 0.25 to 0.27 mmol/L. HDL cholesterol and triglycerides do not change.
The EU authorises disease-risk claims that oat beta-glucan and barley beta-glucan lower blood cholesterol at 3 g a day. Two cautions matter for anyone choosing a supplement rather than a food.
First, the effect depends on viscosity: in a 367-person trial, oat beta-glucan whose molecular weight had been reduced lost about half its effect, and 4 g a day of the low-molecular-weight form did not significantly lower LDL.
Second, in a 263-person, 12-week trial of beta-glucan tablets at 1.5, 3 or 6 g a day, none lowered LDL more than placebo, and gastrointestinal adverse events rose to two thirds of people at 6 g.
Most of the evidence is for oat and barley foods with a known beta-glucan content, and no trial has measured heart attacks or strokes. The evidence here is for oral oat and barley beta-glucan and cholesterol.
Yeast and mushroom beta-glucans used for immune support have their own entry, Beta-Glucans, and so does beta-glucan in skincare, Beta-Glucan (topical).
Beta-glucan from oats and barley is a viscous, soluble fibre. Its LDL-lowering effect depends on that viscosity, which is set by the molecular weight of the beta-glucan and how much of it dissolves in the gut.
In a 367-person trial, 3 g a day of high- or medium-molecular-weight oat beta-glucan lowered LDL by about 5%, but cutting the molecular weight to 210,000 g/mol halved the effect. Products with the same labelled amount can therefore differ.
Barley is excluded from a gluten-free diet. A meta-analysis found pure, uncontaminated oats did not affect symptoms, gut histology or blood tests in coeliac disease, but the evidence was low quality and the trials used pure oats only, so choose products certified gluten-free and check with your clinician.
Not a substitute for prescribed treatment. No interaction is established, but tell the clinician who manages your cholesterol.
No safety data exist for concentrated oat or barley beta-glucan supplements in pregnancy or breastfeeding, so ask a clinician or pharmacist before use. Oats and barley as ordinary foods are a separate matter.
Tip: In the tablet trial, gut adverse events rose with dose (67% at 6 g a day vs 37% on placebo). Lower the dose if symptoms are troublesome.
Oat Beta-Glucan has an evidence score of 6.5/10 — moderate evidence based on 9 indexed studies, including 7 meta-analyses. The viscous soluble fibre in oats and barley. About 3 g a day, mostly eaten in foods, lowers LDL cholesterol by about 0.2 to 0.27 mmol/L in several meta-analyses, but how well it works depends on the product, and a trial of beta-glucan tablets found no effect. Representative study: PMID 27724985.
The commonly studied dose of Oat Beta-Glucan is 3 g a day of beta-glucan from oats or barley, which means 3 g of the beta-glucan itself, not 3 g of oats. Most trials gave it in foods such as oat bran, oat cereals and barley products with a known beta-glucan content, and the largest dose-comparison trial split it over two meals. This is the daily intake in the EU disease-risk claims for oat and barley beta-glucan. Trials used 3.0 to 12.4 g a day, and higher doses did not add a clear further effect. Check the label for the amount of beta-glucan, not just total fibre. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
The best time to take Oat Beta-Glucan is with meals. Take it with food. The trials gave beta-glucan in foods eaten as part of meals, and the largest dose-comparison trial split it into two doses a day.
Oat Beta-Glucan is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are gastrointestinal symptoms such as bloating or discomfort.
CoQ10
Likely helpsA lipid-soluble antioxidant central to mitochondrial energy production, with the strongest trial support for fertility/IVF outcomes and heart failure.
Red Yeast Rice
Likely helpsFermented rice containing natural statins that effectively lower LDL cholesterol — the original statin.
Berberine
Likely helpsActivates AMPK to regulate blood sugar, improve insulin sensitivity, and support lipid metabolism. Its only head-to-head trial with metformin cited here was a 36-person pilot, which does not show it can replace metformin.
Plant Sterols & Stanols
Too few graded studiesPlant sterols and stanols taken at about 2 to 3 g a day, usually in fortified foods or as capsules, lower LDL cholesterol by roughly 6 to 12% in more than a hundred randomised trials. No trial has tested whether they prevent heart attacks or strokes.
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Reviewed by Dr. Baher Al Hakim · Last reviewed October 2026 · evidence from 9 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.