In The Shawshank Redemption, Andy Dufresne (Tim Robbins) manages to escape prison by crawling through 500 yards of a filthy sewage pipe. It seems like a similar effort will be needed to find out how to benefit from fecal transplantation when given for problems like irritable bowel syndrome and metabolic disease/obesity. Some recent studies and associated editorials are noted below.

T Holvoet et al. Gastroenterol 2021; 160: 145-157. Fecal Microbiota Transplantation Reduces Symptoms in Some Patients With Irritable Bowel Syndrome With Predominant Abdominal Bloating: Short- and Long-term Results From a Placebo-Controlled Randomized Trial

• Key finding: At week 12, 56% of patients given donor stool reported improvement in both primary endpoints compared with 26% of patients given placebo (P = .03).
• Commentary: PW O’Toole, F Flanahan. Gastroenterol 2021; 160: 15-17. Full Text: Transplanting Microbes for Irritable Bowels or Irritated Microbes or Both?
  • This editorial stresses that trials of FMT in IBS have had inconsistent results and risks are unclear. “How many clinicians inform patients receiving FMT that the donor microbiota might include components that increase (or decrease) one’s risk of colorectal cancer?” Part of the problem is “due, in part, because a normal microbiome has not been defined.”

E Rinott et al. Gastroenterol 2021; 160: 158-173. Full text Effects of Diet-Modulated Autologous Fecal Microbiota Transplantation on Weight Regain

Key findings:

• In this randomized controlled trial with 90 participants, autologous FMT (aFMT) significantly attenuated weight regain in the green-Mediterranean group (aFMT, 17.1%, vs placebo, 50%; P = .02) and improved insulin resistance: insulin rebound (aFMT, –1.46 ± 3.6 μIU/mL vs placebo, 1.64 ± 4.7 μIU/mL; P = .04) (Graphical abstract below)
• In mice, Mankai-modulated aFMT in the weight-loss phase compared with control diet aFMT, significantly prevented weight regain and resulted in better glucose tolerance during a high-fat diet–induced regain phase (all, P < .05).

Commentary: M Nieurdorp, K Madsen. Gastroenterol 2021; 160: 17-19. Full text The Promise of Maintaining Diet-Induced Weight Loss by Swallowing One’s Own Feces: Time to Provide a Do-It-Yourself Manual?

• “These findings add support to the current body of evidence that the gut microbiota have a role in weight gain and metabolism. However, many questions remain. Indeed, although studies have shown varying degrees of effectiveness of FMT in the improvement of metabolic parameters in human participants, there has been no evidence yet that FMT can induce weight loss in obese patients.”
• “The finding that maintenance of weight loss was only seen in the one dietary group consuming the Mediterranean diet plus green tea and Mankai supplement who received autologous FMT, would suggest that specific microbial profiles may be involved and that weight loss per se may not result in the required microbial profiles.”

My take: Both of these studies show that modulation of the fecal microbiome may be helpful under the right set of circumstances to help with both irritable bowel syndrome and metabolic syndrome. However, ‘hundreds of yards’ of more research is needed to determine if this is really feasible and to assure that the benefits outweigh the potential risks.

Related blog posts:

• Fecal Microbial Transplantation -Evidence for Use Beyond Recurrent Clostridium Difficile | gutsandgrowth
• Effects of FMT on Adolescents with Obesity
• How Much Do We Really Know About Fecal Microbiota Transplantation? | gutsandgrowth
• “Intestinal Microbiota Transplant” -New Terminology for Fecal Transplant | gutsandgrowth
• Not curing obesity with FMT & Remdesivir
• FMT Warning & ‘Get Your Butt in Gear’
• Could Obesity Be Cured/Created at Birth with Manipulation of Microbiome