You've been told to add more fibre to improve your bowel movements and microbiome. But when you try to add prebiotics your bloating and gas gets 10x worse. That doesn't mean fibre and prebiotics don't work for you. It means you have to get very specific about the type.
Why Do Most Prebiotics Make SIBO Bloating Worse?
See most prebiotics like inulin and FOS feed bacteria indiscriminately, good and bad, producing gas as a byproduct. But there's a category of compounds that selectively feeds beneficial bacteria that pathogens literally cannot access, actively suppresses the organisms causing your problems, and produces virtually zero gas.
Polyphenols are the clearest example because around 90-95% pass through your stomach and small intestine completely unabsorbed without producing gas, Arriving in the colon intact where they selectively feed species like Bifidobacterium and Akkermansia whilst having antimicrobial effects against gas producers. A prebiotic that feeds the right bacteria, suppresses the wrong ones, and doesn't produce gas. If you've been avoiding everything fermentable for months this changes what you can do tomorrow morning.
What Makes Human Milk Oligosaccharides Different?
Human milk oligosaccharides take the selectivity even further. Only specific Bifidobacterium strains can utilise them as food, nearly all pathogenic species tested including E. coli and Klebsiella cannot access them at all. In IBS patients HMO supplementation significantly increased Bifidobacterium and butyrate production while reducing gut permeability.
On top of that HMOs physically bind to the receptors on your gut wall that pathogens use to attach, meaning the pathogen shows up and the spot is already taken. Prebiotic, antimicrobial, and barrier-protective without producing a molecule of gas.
How Does S. Boulardii Fit Into SIBO Treatment at Home?
S. Boulardii works differently because it's a yeast not a bacterium, it doesn't compete in the same ecosystem at all. It increases sIgA which traps endotoxin, produces its own enzyme that detoxifies LPS directly, reduces histamine-producing bacteria, and shifts the environment toward species that support barrier function.
And there's one prebiotic particularly helpful in SIBO too, Partially hydrolyzed guar gum was added to standard rifaximin treatment. Rifaximin alone eradicated SIBO in 62% of patients but with PHGG that jumped to 87%. A prebiotic fibre improving SIBO eradication by 25 percentage points. PHGG is selectively fermented by beneficial bacteria, produces far less gas than inulin, and generates the butyrate your gut lining needs to maintain its oxygen gradient.
Your beneficial bacteria have been starving on your restricted diet while the overgrowth continued feeding on whatever you still ate. The answer was never to avoid all prebiotics. It was to use the ones that feed selectively, suppress the problem, and don't produce the gas that set you back every time you tried before.
The compounds worth trying at home include:
- Polyphenols, which pass through unabsorbed and selectively feed Bifidobacterium and Akkermansia
- Human milk oligosaccharides, which only specific Bifidobacterium strains can utilise
- S. Boulardii, a yeast that increases sIgA and detoxifies LPS directly
- Partially hydrolyzed guar gum (PHGG), which boosted rifaximin eradication from 62% to 87%
For more on the underlying levers, see the biggest levers to pull for motility and why the weeds always come back.
