Longevity Briefs: A Self-Experiment To Rejuvenate The Gut

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: The diversity of the gut microbiome declines with age, with negative consequences for gut health, the immune system and the central nervous system. Faecal transplants from younger donors are currently the only known way of restoring lost diversity of bacteria in the gut in a long-lasting manner. Another strategy to improve the health of the gut microbiome is flagellin immunisation – essentially a vaccine against ‘bad’ gut bacteria, in an attempt to encourage the immune system to destroy them more effectively. The effects of faecal transplants on the gut are better studied in animals than in humans. While flagellin has been given to humans as a way of improving the effectiveness of certain vaccines, its effects on the on human gut health hasn’t been studied.

What did the researchers do: In this single person self-experiment, the subject attempted to improve their gut microbiome composition with flagellin immunisation and measure the effects on gut health. The subject was around 50 years old, and received flagellin immunisation in May 2020. They later received a faecal microbiota transplant from a healthy 20 year-old donor at the end of August 2022. Gut health was sampled at various intervals using a service called Viome, which uses genetic sequencing of gut bacteria to estimate diversity, metabolic activity, inflammation and other metrics.

Key takeaway(s) from this research: Microbe diversity decreased after flagellin immunisation, presumably because of the destruction of certain bacterial strains by the immune system. However, most other metrics were improved. Faecal transplant greatly improved gut microbiome diversity, but did not seem to affect other metrics as much as flagellin immunisation, though that might have been because there was simply less remaining room for improvement. These benefits appeared to persist for at least 6 months after the faecal transplant was received.

Faecal transplants are not hard to perform, though they can be unpleasant to receive. They can also have serious side effects, and the donor must be thoroughly vetted and their sample screened for pathogens. This is particularly important for an older recipient, whose immune system may be incapable of suppressing harmful bacteria that would otherwise remain under control in a younger person.