Is Metamucil (psyllium) better than flax seed supplements for promoting regular bowel movements and lowering low-density lipoprotein (LDL) cholesterol levels?

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Last updated: June 9, 2025View editorial policy

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From the Guidelines

Metamucil (psyllium) is generally more effective than flaxseed supplements for promoting regular bowel movements and lowering low-density lipoprotein (LDL) cholesterol levels. When considering the management of bowel regularity and cholesterol levels, it's essential to evaluate the evidence supporting each supplement.

  • Metamucil contains psyllium husk, which forms a gel-like substance that adds bulk to stool and promotes regularity, making it a more effective option for constipation relief compared to flaxseed supplements 1.
  • The standard dose of Metamucil is 1 tablespoon (about 7 grams) mixed in 8 ounces of water, taken 1-3 times daily, and it has been shown to lower LDL cholesterol by 5-10% when taken regularly.
  • Flaxseed does contain beneficial omega-3 fatty acids and lignans that may help with heart health, but its fiber content is less concentrated than psyllium, and the evidence supporting its use for cholesterol reduction is not as strong as that for Metamucil 1.
  • It's crucial to start with a low dose of Metamucil and gradually increase to avoid bloating and gas, and always take it with plenty of water to prevent choking or intestinal blockage.
  • While both supplements are generally safe, Metamucil's more concentrated soluble fiber content makes it the more effective option specifically for improving bowel movements and lowering LDL cholesterol, as supported by the American Heart Association's dietary guidelines 1.

From the FDA Drug Label

PRINCIPAL DISPLAY PANEL MetaMUCIL PSYLLIUM FIBER SUPPLEMENT THERAPY FOR REGULARITY on-the-go! 30 packets 4-in-1 FIBER HELPS SUPPORT: Appetite Control* Heart Health by Lowering Cholesterol† Healthy Blood Sugar Levels* Digestive Health

†See back for information about soluble fiber and heart disease

The FDA drug label does not answer the question.

From the Research

Comparison of Metamucil and Flax Seed Supplements

  • Metamucil, a fiber supplement containing 100% natural psyllium, has been shown to promote regular bowel movements and lower low-density lipoprotein (LDL) cholesterol levels 2, 3.
  • A study found that 92% of pharmacists stated they would recommend Metamucil for bowel regularity and 90% as it provides multiple benefits 2.
  • Flax seed supplements have also been found to reduce constipation symptoms, weight, glycemic and lipid levels in constipated patients with type 2 diabetes 4, 5.
  • A randomized trial found that flaxseed appeared to be superior to psyllium for improving constipation symptoms, weight, glycemic, and lipid control 4.

Effects on Bowel Movements and LDL Cholesterol

  • Psyllium, the active ingredient in Metamucil, has been shown to lower LDL cholesterol levels by 6.7% in men and women with primary hypercholesterolemia 3.
  • Flaxseed has been found to decrease constipation symptoms, weight, glycemic and lipid levels in constipated patients with type 2 diabetes, with significant improvements in LDL cholesterol levels 4, 5.
  • A study found that both flaxseed and psyllium may decrease constipation symptoms, weight, glycemic and lipid levels, but treatment with flaxseed appeared to be superior to psyllium 4.

Key Findings

  • Metamucil and flax seed supplements have been found to have beneficial effects on bowel movements and LDL cholesterol levels 2, 4, 5, 3.
  • The quality of pharmacist's counseling is associated with consumers' adherence and satisfaction to Metamucil 2.
  • Flaxseed appears to be superior to psyllium for improving constipation symptoms, weight, glycemic, and lipid control in constipated patients with type 2 diabetes 4.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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