Faecal Microbiota Transplants May Improve Metabolic Health for Four Years

Growing evidence suggests that the composition of gut bacteria influences the risk of obesity. New findings also support the idea that transferring ‘good’ bacteria through faecal microbiota transplants (FMT) could improve metabolic health for several years.

Put simply, metabolic health describes how effectively the body functions and converts food into energy. The study assessed it using metabolic syndrome: a group of health problems involving high blood pressure, elevated sugar and fat levels in the blood, waist circumference and cholesterol.

Faecal microbiota transplants and metabolic health

Conducted by researchers at the University of Auckland in New Zealand, the study revisits research published five years earlier. In that trial, 87 young adults with obesity received faecal transplant capsules containing a blend of gut bacteria intended to support healthy metabolism.

"Metabolic syndrome has severe consequences, including a doubling in risk of death from heart disease or stroke and a five-fold increased risk of type 2 diabetes," says paediatric endocrinologist Wayne Cutfield, from the University of Auckland.

The transplant did not produce an obvious effect on weight loss. However, it appeared to lower the risk of metabolic syndrome, reducing the likelihood of associated illnesses. The latest results show these health gains may persist for years.

"What is impressive is that just a single [FMT] treatment produced a dramatic reduction in metabolic syndrome that lasted at least four years," says Cutfield.

"This means participants are at much lower risk of developing diabetes and heart disease over the long term."

Four-year follow-up results

For the new analysis, researchers performed follow-up assessments on 55 of the original 87 participants. Of these, 27 had received FMT treatment, while the other 28 had been given a placebo.

There was again no meaningful difference in body mass index (BMI) between the two groups. Yet the volunteers treated with FMT continued to record significantly better metabolic syndrome scores, with improved measures across several health indicators, including a lower body-fat percentage.

The team also found that, to some degree, the beneficial bacterial mixture transplanted four years earlier was still present. This suggests that continuing treatment may not invariably be necessary.

Gut bacteria, obesity and future treatments

The substantial body of existing research indicates a two-way link between obesity and gut bacteria. Diet clearly affects the gut, but the gut microbiome also seems to influence weight and metabolism to a degree.

Swallowing a processed poo tablet may sound rather unpleasant, and some studies indicate that FMT carries risks of its own. Nevertheless, other research points to a range of benefits, and such treatments have been used to address cancers, brain diseases and ageing more broadly.

Having now identified the possible long-term benefits, the researchers want to test larger groups and carry out further work to establish the precise combination of gut microbes that can support metabolic health.

"Imagine being able to program your microbiome to reduce the risk of conditions before they occur," says geneticist Justin O'Sullivan, from the University of Auckland.

"This work is paving the way for next-generation probiotics that target specific conditions through sustained changes to the microbiome."

The research was published in Nature Communications.