Faecal transplants have been a thing for a while.
We have since reported on their potential to reverse the damaging effects of broad-spectrum antibiotic treatment on the gut microbiomes of stem cell transplant patients, and in recent years they have become an accepted treatment for a serious type of diarrhoea.
Now a Danish research team has upped the ante by suggesting they may also help people suffering from obesity and type 2 diabetes.
In trials at the University of Copenhagen, obese mice with unhealthy lifestyles given viruses transplanted from the stool of lean mice put on significantly less weight and appeared to be protected against developing glucose intolerance, a hallmark of diabetes.
The method used is known as Faecal Virome Transplantation. Only the virus in stool was transplanted, and the majority of particles transmitted were so-called bacteriophages – viruses that specifically attack other bacteria and not humans.
“[W]e have influenced the gut microbiome in such a way that the mice with unhealthy lifestyles do not develop some of the common diseases triggered by poor diet,” says Torben Sølbeck Rasmussen, first author of a paper in the journal Gut.
Both obesity and type 2 diabetes are believed linked to imbalances in the gastrointestinal microbiome, also known as gut flora, and it has been discovered that the composition of viruses in the gut plays a crucial role in the balance of this microbiome.
“If one eats poorly for long enough, they risk creating an imbalance in their intestinal tract,” says co-author Dennis Sandris Nielsen. “Here, we have a means of recuperating balance by shooting missing virus particles back into the system.”
The researchers say their study addresses one of the current problems with faecal transplants.
Stool is usually transplanted in an unfiltered form, in the belief that it is the gut bacteria which are most effective. However, in rare cases this produces side effects when diseases are inadvertently transmitted via the transplanted stool bacteria.
“Our study demonstrates that there is an effect after the live bacteria have been filtered from stool. Therefore, primarily virus particles are transmitted. This makes the method safer,” says Nielsen.
He expects that it will be a number of years before it could be broadly deployed, however, and even then would likely be used only in serious cases, not to target general obesity.
Rasmussen also emphasises that it will not be a stand-alone solution: a change in diet would be needed too.
Nick Carne is the editor of Cosmos Online and editorial manager for The Royal Institution of Australia.
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