Change in Fecal Microbes after a Month of Probiotics

Guest BloggerClinical Corner, Microbiome Environment

probiotic capsule

Supplements have always had detractors. “Expensive urine” was what vitamin poppers were said to be making in the early days of mega doses nearly 50 years ago.

With the cost of probiotic supplements, it is fair to ask: are we creating costly stool?

Many millions of people take probiotic supplements trusting in a benefit to their intestinal colonies. Evidence is lacking though, mostly because of the difficulty in isolating a true picture. Bowel prep for that clear window obscures an accurate tally.

The next best thing is a stool analysis.

A team from Korea recently looked at Effects of the Administration of Probiotics on Fecal Microbiota Diversity and Composition in Healthy Individuals. The paper appeared in the Journal of Neurogastroenterology and Motility in July 2018.

Twelve healthy volunteers with an age range of 30-42 years provided stool samples. Then a mixture of Bifidobacterium, Lactobacillus, and Enterococcus probiotics were ingested twice a day for 4 weeks. More stool samples were collected at four weeks and again 2 weeks later. Microbiota was analyzed via 16S ribosomal RNA gene.


The overall diversity of fecal microbiota was not significantly altered by the 4-week administration of probiotics. The researchers found that the proportion of Bacteroidetes, Actinobacteria, Firmicutes, and Proteobacteria was not significantly changed by the 4-week administration of probiotics.

But at the genus level, the proportions of Lactobacillus and Enterococcus increased after the 4 week trial.

That increase disappeared 2 weeks later, when no probiotic supplements were taken in the interim. Obviously the increase does not seem to last long, probably because of homeostasis or dietary influence.

Of course, may other factors come into play

Diet, host genetics, diseases, and medications influence the microbiota. The researchers generally tried to standardize some of the lifestyle factors such as age, working time, routine activities, medications, alcohol drinking, smoking, and eating habits. But tight control was not accomplished.

Still, worth comment is the return to set point after the probiotics were stopped. It is known that a person’s microbiota stays fairly constant throughout life with the beginning and end of life as notable exceptions.

Homeostasis is a benefit to the organism until change is necessary to introduce more helpful communities of microbes. This imbalance occurs in many diseases beyond the gut.

While diversity did not change, the proportion of fecal microbiota at the genus level did. The benefits inside the body are what matters. Much evidence points to a strong impact of probiotic supplements on sustaining health and repairing disorders across the arc of bodily function.


Related reading from IPA

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