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Perhaps the most surprising and widely accepted medical treatment that arisen as a result of the research on the microbiome is fecal transplant. This procedure is over 90% effective in cases of infection with Clostridium difficile, a life threatening and often reoccurring condition. It is has been shown to be far more effective than antibiotic treatment.

In studies on animals, fecal transplant has proven to a useful and revealing procedure to better understand the role of the mircrobiota in obesity. For example, if you implant microbes from an obese mouse into germ-free mice this will increase their weight. And if you implant microbes from a lean mouse into germ-free mice this will have the opposite effect. And that is not all. One experiment implanted germ-free mice with fecal microbiota from human twin pairs who were either obesity or lean. The mice receiving microbiota from the obese twin showed more weight gain and adiposity than those receiving microbiota from the lean sibling.

Further research has demonstrated that a high-fat diet itself can change the relative abundance of microbial species in the gut and lower the overall diversity of microbiota. And there are differences in bacterial diversity between lean and obese humans as well. The implications of this research are remarkable since the problem of obesity is a critical concern for world health. Whether fecal transplant is viable or even reasonable and acceptable alternative is a topic of huge debate.

Numerous fecal transplant clinical trials are being conducted on other conditions, including ulcerative colitis and obesity. These studies are in a preliminary stage and there are many questions that must still be answered. How, for example, do researchers know who is the best fecal donor candidate? Should it be a relative, a best friend, or a healthy stranger? What is the best way to obtain a sample and store it? What was it that went wrong when researchers tried to purify the stool sample and put it into pill form? Can fecal transplant cure other diseases?



For information on clinical trials go to: and enter “fecal microbiome transplant” and “probiotics” in the search box.

Ridaura VK et al. Gut microbiota from twins discordant for obesity modulate metabolism in mice. Science 2013 Sep 6; 341(6150):1241214.

Konig J et al., Consensus report: faecal microbiota transfer – clinical

applications and procedures. Aliment Pharmacol Ther 2017; 45: 222–239

Chu ND et al., Profiling Living Bacteria Informs Preparation of Fecal Microbiota Transplantations. Zoetendal EG, ed. PLoS ONE 2017;12(1):e0170922.

Vermeire S et al. Donor species richness determines faecal microbiota transplantation success in inflammatory bowel disease. J Crohns Colitis 2016; 10: 387–94. 54.