Best Prebiotic Fibers for L. reuteri Fermentation

A ranked look at prebiotic fibers that may help support L. reuteri fermentation when inulin is not available.

21 March 2025

Gut health

Fermentation

L. reuteri

TL;DR

Inulin is still the most predictable starting fiber for L. reuteri fermentation.
Other prebiotic fibers may work, but they change speed, texture, and the final culture.
Use this as a ranked fallback guide, not proof that every fiber behaves the same way.

Dr. William Davis, author of Super Gut, recommends using inulin to ferment Lactobacillus reuteri (Davis, 2022). This prebiotic fiber provides an ideal fuel source for bacterial growth. But what happens if you run out? Instead of stopping your batch, you might be able to substitute other prebiotic fibers that also support L. reuteri—some ferment fast, others provide a slower, sustained effect.

This ranked table explores 39 prebiotic fiber sources, comparing their fermentation speeds and effectiveness in feeding L. reuteri. While inulin remains a top choice, these alternatives might work in a pinch when you’re low on supplies.

References

Davis, W. (2022). Super Gut: The Four-Week Plan to Reprogram Your Microbiome, Restore Health, and Lose Weight. Penguin Random House.