In this video, Dr. Patrick Nemechek (inventor of the Nemechek Protocol™) explains how he thinks about bacterial overgrowth and why he uses inulin in some patients and rifaximin (Xifaxan® in the U.S.) in others.
His discussion is grounded in a practical clinical framework: the bacteria that normally live in the upper intestinal tract (small intestine) are fundamentally different from the bacteria that normally live in the colon, and the concentrations are dramatically different. In his terminology, he refers to the upper-tract bacteria as “birds” and the colon bacteria as “fish.”
Below is a source-faithful summary of what Dr. Nemechek describes about inulin and rifaximin, including how he approaches age-related response patterns and why persistent symptoms after treatment may not always mean ongoing overgrowth.
Dr. Nemechek’s “birds vs. fish” framework for bacterial overgrowth
Dr. Nemechek describes the small intestine as a place where there are normally relatively few bacteria (“birds”), while the colon contains very large numbers of different bacteria (“fish”). He emphasizes that, in bacterial overgrowth, “fish” bacteria can be present where “birds” normally predominate, and the number of bacteria in the upper intestinal tract can rise dramatically.
In his conceptualization, the goal is to restore a more normal separation—encouraging upper-tract “bird” bacteria and reducing the presence of colon-type “fish” bacteria in the small intestine.
How inulin is used in this framework
Dr. Nemechek describes inulin as essentially “bird food” within his model. He explains that inulin predominantly feeds the bacteria that normally live in the upper intestinal tract. In his description, those “bird” bacteria produce acids, and he notes that the “fish” bacteria do not like those acids. Through this fermentation effect, he says the “fish” bacteria regress, which helps re-establish separation back toward normal.
He adds that in adults, inulin can help intestinal symptoms somewhat and may help someone feel “a little bit better.” However, he says that, in the focus of his work—trying to reverse what he calls chronic autonomic damage—inulin does not provide enough of an effect for him to “get the brain better” in those adult cases.
Dr. Nemechek’s age-based pattern he observes with inulin
Dr. Nemechek describes an age trend from his clinical experience:
- Children under ~10: he says inulin “does a great job” and is enough to get the brain to start to recover.
- Ages ~10–20: he describes a variable transition zone, where some may do well on inulin for a time, but others may need to move to rifaximin.
- Over ~20: he states inulin “doesn’t work” in the way he needs for neurological recovery, and he uses rifaximin.
Importantly, he also states plainly that he does not know why this shift happens. In his words, “I just don’t know—that’s the honest answer.” Practically, he explains that if a teenager (for example, age 14) is recovering nicely on inulin, he will keep them on it, while acknowledging it may stop working at some point and rifaximin may eventually be needed.
What rifaximin is, and why Dr. Nemechek uses it differently
Dr. Nemechek describes rifaximin as a “special antibiotic” and “very unique,” stating it is not like other antibiotics that “kind of damage the gut.” He notes it has been around for about 30 years and has been used predominantly for a liver condition called hepatic encephalopathy.
He explains that hepatic encephalopathy can involve colon-type bacteria (“fish”) being present where small-intestine bacteria (“birds”) normally live in adults with cirrhosis, and he describes those bacteria producing ammonia that can cause confusion. He then draws a parallel to autism within his framework, describing “fish” living where “birds” are and producing a different chemical he names as propionic acid. (This parallel is presented as his clinical interpretation and analogy in the video.)
How he says rifaximin works in his model
Dr. Nemechek lists several features of rifaximin as he uses it in this context:
- He states you don’t absorb it into the bloodstream (which he frames as beneficial and associated with limited side effects).
- He says it is only effective in the small intestine because of bile salts, which are absorbed before reaching the colon—so, in his description, the drug “quits working” in the colon.
- He states it does not harm the natural “bird” bacteria that normally live in the small intestine.
- He explains it targets “fish” bacteria only when they are up in the small intestine (because that’s where it is active), which aligns with the goal of removing colon-type bacteria from the upper tract.
He also emphasizes that when he uses rifaximin for this purpose, it is taken twice a day for ten days (contrasting this with hepatic encephalopathy cases where many adults may take it twice a day year-round).
Why symptoms can persist after rifaximin in Dr. Nemechek’s view
Dr. Nemechek addresses a common concern he hears: someone may take rifaximin and still have bloating or constipation. He explains that, in his view, those can be autonomic symptoms—“brain symptoms”—rather than bacterial overgrowth symptoms. In other words, he cautions that ongoing GI discomfort after rifaximin does not automatically mean the overgrowth itself is still present; it may reflect a different issue in his framework.
Durability and relapse concerns: inulin vs. rifaximin
Dr. Nemechek also compares what happens if a child later needs antibiotics for something like an ear infection. He describes an advantage of inulin: because it is taken every day, it helps maintain the separation between “birds” and “fish.”
By contrast, he explains that if rifaximin is used (because the patient is old enough or didn’t respond to inulin), there is nothing “maintaining” that separation afterward in the same way. In his view, a later antibiotic course has the potential to trigger a relapse of bacterial overgrowth, requiring re-treatment. He notes that this is “not that big of a deal,” but is a practical reason to use inulin when it is sufficient.
What about other fibers?
When asked (implicitly) about alternatives, Dr. Nemechek’s position is straightforward: he says he doesn’t know whether other fibers might work, but he is “very practical” and emphasizes that inulin works “great,” is inexpensive, and readily available. His recommendation in the video is to keep things simple rather than trying to finesse the approach with other products.
How he summarizes his clinical approach
Dr. Nemechek’s take-home summary in the video is:
- Under ~10: inulin is the way to go.
- ~10–20: start with inulin; if there’s a response, stay with it, and if not, step up to rifaximin.
- Over ~20: rifaximin is typically needed if the goal is neurological recovery in his framework.
Educational medical disclaimer: This article summarizes statements and clinical perspectives shared by Dr. Patrick Nemechek in the referenced video and is for general education only. It is not medical advice and is not a substitute for diagnosis or treatment by your own clinician. Do not start, stop, or change supplements or prescription medications (including antibiotics such as rifaximin) without medical supervision.
