tuneTypical Dose
About 7-12 g/day split doses
Fiber Supplement
Psyllium
Plantago ovata husk
Evidence TierAWADA NOT PROHIBITED
watchEffect Window
Days to weeks for bowel outcomes. Weeks for lipid outcomes.
check_circleCompliance
WADA NOT PROHIBITED
Overview
Clinical Summary
Psyllium is a viscous soluble fiber with strong evidence for bowel and lipid support.
Psyllium has strong evidence for lowering LDL cholesterol and improving constipation-related bowel outcomes when taken consistently with adequate fluid. A 2025 dose-response meta-analysis reinforces that lipid benefits remain reliable across a wide range of studied protocols, while triglyceride and HDL effects are smaller and less consistent.
Nonfermented gel-forming soluble fiber that improves stool hydration/transit and lowers atherogenic lipids through bile-acid related mechanisms.
Outcomes
What This Is Expected To Influence
Primary Outcomes
- Constipation symptom and stool-quality improvement
- LDL-C/non-HDL-C/apoB reduction
Secondary Outcomes
- Modest systolic blood-pressure reduction
- Population-dependent glycemic support
Safety
Contraindications and Interactions
Contraindications
- Bowel obstruction/fecal impaction
- Severe swallowing difficulty
- Inability to maintain fluid intake
Side effects
- Bloating
- Flatulence
- Abdominal cramping/fullness during titration
- Nausea
- Vomiting
- Dyspepsia
- Changes in bowel movement frequency and consistency
Interactions
- Reduced absorption of oral medications if co-administered. Separate oral meds and psyllium by at least 2 hours.
- Blood-glucose-lowering drugs (Probable/Moderate) - Psyllium may further reduce fasting glucose and HbA1c when combined with drugs that lower blood glucose.
- Levothyroxine sodium (Possible/Moderate) - Psyllium may reduce levothyroxine absorption. Avoid same-time dosing.
- Riboflavin (Vitamin B2) and iron (Possible/Minor) - Co-administration may reduce micronutrient absorption.
- Metformin (Theoretical/Minor) - Psyllium may enhance metformin absorption.
- Blood-glucose-lowering supplements (Theoretical/Unknown) - Psyllium may further reduce fasting glucose and HbA1c when combined with glucose-lowering supplements.
- Other bulking fibers (Probable/Minor) - Additive GI bloating, gas, or cramping can occur when started together.
Avoid if
- People using blood-glucose-lowering drugs
- People using levothyroxine sodium
- Acute undiagnosed abdominal pain
- Significant dysphagia
- Known severe intolerance to psyllium
- Inability to maintain fluid intake
Evidence
Study-level References
psyllium-SRC-001Systematic review and meta-analysis of RCTs.
Sourceopen_in_newJovanovski E, et al. Effect of psyllium (Plantago ovata) fiber on LDL cholesterol and alternative lipid targets: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2018;108(5):922-932. doi:10.1093/ajcn/nqy115. PMID:30239559.
Population: Adults across lipid/cardiometabolic risk strata.
Dose protocol: Median about 10.2 g/day psyllium for >=3 weeks.
Key findings: Significant lowering of LDL-C, non-HDL-C, and apoB.
Notes: Moderate quality evidence for LDL/non-HDL effects.
Paper content
Significant LDL reduction.
psyllium-SRC-002Systematic review and meta-analysis.
Sourceopen_in_newZhu R, et al. Plantago consumption significantly reduces total cholesterol and LDL cholesterol in adults: systematic review and meta-analysis. Nutr Res. 2024;126:123-137. doi:10.1016/j.nutres.2024.03.013. PMID:38688104.
Population: 29 RCTs, 2769 participants.
Dose protocol: Plantago/psyllium and related formulations.
Key findings: Significant LDL-C and TC reduction.
Notes: Includes varied populations and preparations.
Paper content
Significant LDL-C and TC reduction.
psyllium-SRC-003Multisite randomized double-blind parallel trial.
Sourceopen_in_newMcRorie JW, et al. Psyllium is superior to docusate sodium for treatment of chronic constipation. Aliment Pharmacol Ther. 1998;12(5):491-497. doi:10.1046/j.1365-2036.1998.00336.x. PMID:9663731.
Population: 170 adults with chronic idiopathic constipation.
Dose protocol: Psyllium 5.1 g BID vs docusate 100 mg BID for 2 weeks.
Key findings: Psyllium superior for stool softening and bowel outcomes.
Notes: Older study but direct comparator and objective stool metrics.
Paper content
Psyllium superior for stool softening and bowel outcomes.
psyllium-SRC-004Randomized placebo-controlled trial.
Sourceopen_in_newNoureddin S, et al. Effects of psyllium vs placebo on constipation, weight, glycemia, and lipids in type 2 diabetes with chronic constipation. Complement Ther Med. 2018;40:1-7. doi:10.1016/j.ctim.2018.07.004. PMID:30219432.
Population: Adults with type 2 diabetes and chronic constipation.
Dose protocol: 10 g psyllium twice daily for 12 weeks.
Key findings: Improved constipation and selected metabolic outcomes.
Notes: Modest sample and single setting.
Paper content
Improved constipation with supportive cardiometabolic directionality.
psyllium-SRC-005Systematic review and meta-analysis of RCTs.
Sourceopen_in_newClark CCT, et al. The effect of psyllium supplementation on blood pressure: a systematic review and meta-analysis of randomized controlled trials. Korean J Intern Med. 2020;35(6):1385-1399. doi:10.3904/kjim.2019.049. PMID:32066221.
Population: Adults with varied cardiometabolic profiles.
Dose protocol: Variable psyllium supplementation protocols.
Key findings: Small significant systolic BP reduction.
Notes: Moderate sample and outcome heterogeneity.
Paper content
Small but significant BP lowering.
psyllium-SRC-006Meta-analysis.
Sourceopen_in_newGibb RD, et al. Psyllium fiber improves glycemic control proportional to loss of glycemic control: a meta-analysis of data in euglycemic subjects, patients at risk of type 2 diabetes mellitus, and patients being treated for type 2 diabetes mellitus. Am J Clin Nutr. 2015;102(6):1604-1614. doi:10.3945/ajcn.115.106989. PMID:26561625.
Population: Euglycemia to treated type 2 diabetes populations.
Dose protocol: Psyllium before meals in many included protocols.
Key findings: Larger glycemic benefit in poorer baseline control.
Notes: Includes sponsor-associated datasets. External replication context important.
Paper content
Modest glycemic improvement, larger in poorer baseline control.
psyllium-SRC-007Systematic review and dose-response meta-analysis of randomized controlled trials
Sourceopen_in_newGholami Z, Paknahad Z. Psyllium supplementation and lipid profiles. Systematic review and dose-response meta-analysis of randomized controlled trials. Genes Nutr. 2025;20(1):27. doi:10.1186/s12263-025-00786-5. PMID:41366295.
Population: Adults enrolled in psyllium lipid-profile trials
Dose protocol: 41 RCTs, 2049 participants, dose-response meta-analysis.
Key findings: Confirms significant lowering of LDL cholesterol and total cholesterol, with nonsignificant effects on triglycerides and HDL cholesterol.
Notes: Strengthens the lipid claim and supports a broad practical dose range rather than one narrow protocol.
Paper content
Dose-response meta-analysis of 41 RCTs confirmed that psyllium significantly lowers LDL cholesterol and total cholesterol, while triglyceride lowering and HDL increases were not statistically reliable.
psyllium-SRC-008Randomized, placebo-controlled trial.
Sourceopen_in_newReid JESJ, Alhasani AT, MacCalman T, et al. A randomised, placebo-controlled trial in healthy humans of modified cellulose or psyllium evaluating the role of gelation in altering colonic gas production during inulin co-administration. Food Funct. 2026;17:1794-1805. doi:10.1039/d5fo03532e. PMID:41636227.
Population: Healthy adult volunteers.
Dose protocol: Psyllium versus placebo co-administered with inulin in 30 healthy adults.
Key findings: Psyllium significantly reduced breath hydrogen production compared to placebo, supporting its non-fermentable gel-forming mechanism.
Notes: Adds mechanistic human evidence for why psyllium causes less gas than fermentable fibers.
Paper content
This randomized placebo-controlled trial in 30 healthy adults tested whether psyllium or modified cellulose could reduce colonic gas production when co-administered with inulin (a highly fermentable fiber). Psyllium significantly reduced initial breath hydrogen production compared to placebo, supporting the clinical observation that psyllium is better tolerated than fermentable fibers and can mitigate gas production. The findings reinforce the practical advantage of psyllium as a non-fermentable gel-forming fiber with less gas-related intolerance.