The Gut Microbiome + Dysbiosis with Dr. Mark Pimentel

Dr. Mark Pimentel, Executive Director of the MAST program at Cedars-Sinai in Los Angeles, shares groundbreaking insights into the small intestinal microbiome that challenge long-held beliefs about gut bacteria. Findings from his team’s REIMAGINE study reveal that the small intestine is far from sterile, as previously thought—instead, it harbors substantial bacterial communities that play a critical role in health and disease, especially in conditions such as IBS and SIBO.

• E. coli and Klebsiella act as aggressive "Ferrari" bacteria that outcompete other microbes and destroy microbial diversity when overgrown inducing a "apocalyptic" disruption of the small bowel microbiome.
• Lactobacillus, commonly found in many probiotics, may act as a disruptor in the small intestine and new research correlates higher small intestinal levels with obesity and unhealthy aging (more research needed)
• The PLACIDE trial found probiotics didn't reduce C. diff or antibiotic-associated diarrhea but did increase bloating
• Food poisoning is the only proven cause-and-effect trigger for IBS, with stress acting as a modifier rather than initiator
• Combining rifaximin with NAC works 10x better for SIBO by targeting bacteria in both intestinal fluid and mucus
• A new compound (CS06) shows promise for reducing methane production and relieving constipation
• Three distinct gas patterns (hydrogen, methane, hydrogen sulfide) correlate with different symptom patterns and respond to targeted treatments

This episode was sponsored by Salix Pharmaceuticals. 

Resources: 

DDW 2025 Abstracts by the Mast Program and Dr. Pimentel

A Novel Microbiome Therapy, CS-06 (MTD Blocker), Reduces Methane Production in Stool Culture

Real World Study of Three-Gas Breath Testing Nationwide and The Association with Symptoms

Learn more about Kate and Dr. Riehl:

Website: www.katescarlata.com and www.drriehl.com
Instagram: @katescarlata @drriehl and @theguthealthpodcast

Order Kate and Dr. Riehl's book, Mind Your Gut: The Science-Based, Whole-body Guide to Living Well with IBS.

The information included in this podcast is not a substitute for professional medical advice, examination, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider before starting any new treatment or making changes to existing treatment.