Unraveling SIBO.

Causes of small intestinal bacterial overgrowth

The small intestine keeps bacteria in check with three defenses: stomach acid, which kills most microbes on the way in; digestive enzymes and bile, which make the environment inhospitable; and the migrating motor complex, a cleansing wave of contractions that sweeps the small intestine clear between meals. SIBO develops when one or more of those defenses fail.

Impaired gut motility is the most common driver. Anything that slows the migrating motor complex — diabetes, hypothyroidism, scleroderma, a prior bout of food poisoning that damaged the gut's nerve signaling, or simply eating constantly so the cleansing wave never runs — lets bacteria linger and multiply.

Structural abnormalities create pockets where bacteria collect: small intestinal diverticula, adhesions or strictures after abdominal surgery, or a compromised ileocecal valve that lets large-intestine bacteria flow backward. Low stomach acid, often from years of proton pump inhibitors, removes the first line of defense entirely. A weakened immune system and a history of gastrointestinal infections raise the risk further.

Why conventional treatment so often has to be repeated

Antibiotics are good at reducing bacterial counts. What they cannot do is restart a sluggish migrating motor complex, raise stomach acid, or repair an intestinal lining. When treatment ends and those conditions are unchanged, the small intestine is just as hospitable to overgrowth as it was before, and symptoms return within months.

Restrictive diets have the same limitation from the other direction. A low-FODMAP or elemental diet starves the bacteria of fermentable fuel, which quiets symptoms, but it is not a long-term way to eat and it does nothing to correct the mechanics that allowed the overgrowth. Patients cycle between relief and relapse, adding foods to an ever-growing list of triggers.

Functional medicine and SIBO

The functional medicine approach treats SIBO as a symptom of a gut that has lost its defenses, not as a bacterial problem to be bombed and forgotten. The first job is to confirm the overgrowth and understand what is driving it. Organic acid testing measures the metabolic by-products your gut microbes produce, and the pattern tells us whether bacterial overgrowth, fungal overgrowth, or oxalate handling is the main issue — a distinction that changes the entire protocol.

Clearing the overgrowth uses botanical antimicrobials paired with a mono-meal eating plan: one food per meal, organic meats and vegetables, so the bacteria have nothing to ferment while the antimicrobials work. We re-evaluate at day 10 and adjust rather than running a fixed course and hoping.

The part conventional care skips is what comes next. Prokinetic support restores the migrating motor complex. Stomach acid is corrected where it is low. The gut lining is repaired with targeted nutrients, and only then is the microbiome reseeded — first with a resilient yeast-based probiotic, then a broader strain. This gut-first sequence is also the foundation for the hormone and metabolic work many of our patients go on to do, because none of it holds while the gut is inflamed.

Taking action on your symptoms

Bloating that builds after meals is not something to live with, and it is not something a probiotic from the pharmacy will fix — if probiotics make you worse, that reaction is itself a clue pointing toward overgrowth. The sooner the overgrowth is confirmed and cleared, the less damage the intestinal lining takes and the faster nutrient levels recover.

If you have been managing an IBS diagnosis for years without real improvement, or you recognize the pattern described on this page, the next step is a consultation with our functional medicine team in Jacksonville or Orange Park. We will tell you whether testing is appropriate, what it will show, and what the plan looks like from there.