Psyllium vs methylcellulose: key differences
Reviewed September 15, 2026
Direct answer: Both are bulk-forming fibers. Psyllium is a viscous, gel-forming soluble fiber with support for constipation and global IBS symptoms. Methylcellulose is a synthetic, nonfermentable fiber that may produce less gas, but it has less direct evidence for IBS outcomes.
What changes the experience
| Feature | Psyllium | Methylcellulose |
|---|---|---|
| Source | Plant husk | Modified cellulose |
| Fermentation | Relatively low | Nonfermentable |
| Texture | Forms a gel | Thickens differently |
For IBS
ACG supports soluble fiber for global IBS symptoms. Monash describes psyllium and methylcellulose as less gas-forming options, while noting that psyllium has more supportive study data.
How to choose
Compare the active ingredient and dose on the label. Introduce one product slowly, use adequate liquid, and judge both symptom response and tolerance.
Sources
- American College of Gastroenterology: Soluble Fiber for IBS (accessed September 15, 2026)
- Monash FODMAP: Fibre Supplements & IBS (accessed September 15, 2026)