Prebiotic supplementation could replace the low FODMAPs diet as a treatment for functional gut disorders (IBS, constipation, functional dyspepsia, etc.). A 4-week study compared the effects of a prebiotic supplement plus Mediterranean-type diet, versus a placebo supplement plus low FODMAP diet for 2 weeks. Fecal microbiota composition, intestinal gas production, and digestive sensations were measured outcomes. After 4 weeks, both groups showed improvements in GI symptoms but only the prebiotic group showed significant improvements in microbial composition. (The FODMAP group actually showed an increase in pathogenic-associated bacteria). Two weeks after the intervention, improvement persisted in the prebiotic group but not in the FODMAP group. Gastroenterology

→Takeaway: Based on 20+ years of clinical experience, Dr. Chutkan does not recommend the low FODMAP diet in her practice, including in those patients with functional GI disorders. The low FODMAP diet was created as a diagnostic tool for IBS, not as a therapeutic diet. While it may alleviate symptoms, it does not treat the condition at its root and may deplete the gut microbiome of beneficial gut bacteria – the very thing we want to increase in those with functional GI disorders. This study illustrates that well (although, we’d rather prebiotics come from food, where they are much more effective, instead of a supplement). For dietary guidelines that improve microbial composition and treat functional GI disorders at their root, check out Dr. Chutkan’s Veleo diet, which can be found in her 2015 book, The Microbiome Solution.

Lastly, is the Mediterranean diet really a placebo? Probably not! It’s rich in plant-based, high-fiber foods that promote the growth of beneficial gut bacteria and has been linked to a myriad of health benefits. Begs the question: was it the prebiotic supplement or the diet (or the combination of the two!) that resulted in positive microbial and symptomatic changes?