Single course oral fecal microbiota transplant in adolescents with obesity linked to lower body fat and metabolic risk four years later. Digest
Adolescent obesity often persists into adulthood and raises cardiometabolic risks, but altering the gut microbiome may help shift long-term health trajectories. Researchers tested whether taking capsules containing gut microbes from healthy donors during adolescence could leave durable clinical and microbiome changes years later.
Researchers followed up on a previous trial where adolescents received either gut microbiota from healthy lean adults or a placebo. About four years later, 55 participants returned for assessment. The team measured body composition, metabolic markers, and gut microbial and viral profiles using DNA sequencing.
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At the four year visit, several cardiometabolic and body composition measures favored the transplant group:
- Waist circumference was 10 cm lower in the fecal transplant group.
- Total body fat percentage was 4.8 points lower.
- A metabolic syndrome severity score was lower.
- The inflammation marker hs-CRP was 68 percent lower.
- HDL cholesterol was 0.16 mmol per liter higher.
These health differences were accompanied by lasting shifts in the gut microbiome. Adolescents who received donor microbes had a more diverse and markedly reshaped gut microbiome compared with placebo. Signatures of donor bacteria could still be detected years later, and participants who took up more donor strains soon after treatment tended to retain more of them long term. The gut bacteriophages – viruses that infect bacteria – also showed lasting donor patterns. Some of these microbial and viral differences were linked with healthier metabolic scores and weight change, although these links cannot prove cause and effect.
Conclusion:
A single course of oral fecal microbiota transplant during adolescence was followed by lower central adiposity and body fat, lower systemic inflammation, and a better composite metabolic risk score about four years later, while BMI remained similar. However, it's important to mention that BMI is a limited measure because it doesn't distinguish between fat and lean mass and can therefore miss meaningful shifts in fat distribution. The gut microbiome continued to show donor traits, which might help explain the observed health effects. However, the study has limitations: it was unblinded, had high dropout rates, didn't track medication or lifestyle changes continuously, and used a statistical approach that may increase false positives. Overall, the results are promising, but they warrant cautious interpretation and further confirmation. Learn more about the microbiome in episode #70 featuring Dr. Eran Elinav.