Catheter used to take small intestine samples during synbiotics study

A new study on a synbiotic used an unusual method to sample the changes the intervention wrought in the small intestines of the subjects. The researchers used a long catheter to sample microbiota at several locations in the gut. 

The new research was published in the journal Gut Microbes. Titled “Spatio-temporal dynamics of the human small intestinal microbiome and its response to a synbiotic,” it was the work of researchers associated with several universities in the Netherlands as well as several who are employees of Winclove Probiotics, which supported the study in part via a public/private research partnership. 

The researchers were attempting to judge the reaction of study participants to a synbiotic intervention, which in this case was a combination of a multi-strain probiotic combined with a dosage of fructooligosaccharide. 

The probiotic portion of the intervention was a proprietary Winclove formula, branded as Ecologic 825. This is a combination of nine probiotic strains: Lactococcus lactis, Lacticaseibacillus paracasei, Lactobacillus acidophilus, Ligilactobacillus salivarius, Lacticaseibacillus casei, Lactiplantibacillus plantarum, Bifidobacterium bifidum, Bifidobacterium lactis and Bifidobacterium lactis, which together provided 1.5 billion CFU (colony forming units). Winclove has long been an advocate of multi-strain probiotics. 

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The other portion of the test product is a fructooligosaccharide designated as FOS P6. It was used in a 10-gram dosage. 

The researchers’ goal was to investigate how the intervention changed the microbiota in the small intestine. They noted that most probiotics research focuses on changes in the fecal microbiota. Fecal samples are easy to take and there is good data correlating what is found in those samples to health outcomes. 

But that still means researchers must infer what changes took place in the small intestine based on microbiome changes further downstream. The present study aimed to change that and get a detailed picture on what microbial changes occurred in the small intestine, where exactly they took place, and when. 

The researchers recruited 20 healthy subjects, divided into two groups. One group ingested two daily doses of the synbiotic intervention, while the others took a placebo. They did this for two weeks, while they maintained their normal diets in the meantime. 

Unusual study design

The researchers resorted to an extraordinary method to get their data on the makeup of the microbiome in the small intestine. The subjects all came into the clinic for a baseline measurement, taken six days before the start of supplementation and after an overnight fast, when a catheter was inserted into their noses and snaked through their stomachs and into their duodenums. 

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At a structure called the ligature of Treitz — the boundary between the duodenum and the jejunum — the forcible snaking stopped. This is the point at which the small intestine starts to become highly folded, making it difficult, if not impossible, to continue to snake the catheter through that labyrinthine path.  

At that point, a small balloon was inflated at the end of the catheter. This used the body’s own peristaltic muscle contractions to push the balloon along, snaking the catheter behind it, until it reached the far end of the small intestine. It took several hours for the catheter to reach its final position. 

The catheter had small holes in it at intervals to let in samples of the microbiome taken at specific locations along the small intestine. 

The catheter procedure was repeated on the 14^th day, and on that day, the contents of the small intestine were sampled three times. One was in the morning after the overnight fast, another was about two hours after ingesting the morning does of the symbiotic, and again about an hour after a standard lunch of noodles. Fecal samples were also taken. 

Valuable data gathered

The researchers found that the makeup of the microbiome was significantly different at each location at baseline. These differences were greatest after the morning fast, while later in the day these differences faded to insignificance. 

After the synbiotic ingestion, they noted brief (about two hours) spikes in the relative abundance of the microbes contained in the formula. 

The authors said the study provides valuable data for what’s happening in the small intestine but leaves more questions over the overall dynamics of the system. 

“We demonstrated significant differences in microbial and metabolomic composition at baseline between duodenum, jejunum, proximal ileum content and feces,” the researchers wrote. “In addition, the significant difference in microbial composition along the small intestine was most pronounced in the morning after overnight fasting, while it was not always measurable around noon or in the afternoon. Two weeks of synbiotic supplementation did not affect the overall microbiota and metabolomic composition in small intestinal fluids and feces differently from placebo. Moreover, small intestinal microbiota is highly dynamic, and ingested probiotic bacteria were shown to lead to a transient spike in the relative abundance of corresponding genera and ASVs, suggesting their passage through the entire gastrointestinal tract.”