I have been discussing how the microbe, Lactobacillus reuteri, is ubiquitous in mammals and in humans unexposed to antibiotics and other microbiome-disruptive factors such as food additives, glyphosate, other pharmaceuticals, etc.

If we were to examine the feces of squirrels, raccoons, or chickens, they all have L reuteri. If we studied the feces of indigenous human populations in remote jungles of New Guinea or the Brazilian rainforest, they also all have L reuteri. A recent fascinating study of ancient microbial DNA in southeastern Spain has identified what is believed to be fecal material from Neanderthals who populated the region 45,000 to 60,000 years ago—and they had L reuteri. (Anthropologists have evidence that Homo sapiens and this different species, Homo neanderthalensis, co-existed for tens of thousands of years before they became extinct.)

Even Dr. Gerhard Reuter, who discovered this microbial species in human breast milk in 1962, had no problem finding it at first. Over the ensuing 40 years of his microbiology career in Germany, he had increasing difficulty in recovering this microbe. And, indeed, subsequent analyses have demonstrated that this species has almost disappeared from the modern human microbiome.

The widespread loss of L reuteri should come as no surprise, given its susceptibility to common antibiotics such as ampicillin, amoxicillin, and others. Ironically, despite its susceptibility to antibiotics, it is itself a producer of potent bacteriocins, natural peptide antibiotics effective against stool species such as E coli, Klebsiella, and Campylobacter. L reuteri is such an effective antimicrobial against gastrointestinal pathogens that my microbiologist friends tell me that they occasionally clean their fermentation vats with this species. But not only is L reuteri a producer of at least 4 varieties of bacteriocins, it is also unique in that it colonizes the upper gastrointestinal tract, precisely where the battleground for SIBO occurs. Could the widespread loss of L reuteri from modern human microbiomes be one of the reasons that small intestinal bacterial overgrowth,SIBO, has become epidemic, now afflicting at least 100 million Americans by my estimation? I think it is—restoring L reuteri may therefore be part of the solution and the reason why I include this species in my recipe for “SIBO Yogurt” that, so far, has eradicated SIBO, as detected by AIRE H2 breath testing, in 90% of people who have tried it. (See my Super Gut book for the SIBO Yogurt recipe if you’d like to give this a try before resorting to antibiotics to eradicate SIBO.)

Animals have it, indigenous human populations have it, even Neanderthals had it, and you should have it, too.

Photo courtesy Smithsonian Magazine and John Gurache/Chip Clark via Wikicommons under Public Domain