Faecal microbiota transplant (FMT)

Autism spectrum disorder

Autism Spectrum Disorder is a neurodevelopmental spectrum condition that can affect social communication and behaviour.  

A systematic review found that FMT appears to help with some of the challenges experienced in children with autism.

However, none of the studies so far have been controlled. This means there can be lots of bias in the results. To truly understand if FMT is helpful, better quality trials are needed, called randomized, controlled trials.

Irritable bowel syndrome

Irritable bowel syndrome affects around 1 in 10 people. It can be caused by food intolerances, heightened gut sensitivity, immune dysfunction, and changes to the gut microbiota.  

A meta-analysis of 484 people across eight randomized, controlled trials found that, overall, FMT was not helpful for IBS. This might be because IBS has many potential different causes. Future FMT studies in IBS should look to see if FMT works better in those with an altered gut microbiota. 

For example, small intestinal bacterial overgrowth (SIBO) is a condition that can sometimes mimic IBS. Excess bacteria in the small bowel contribute to bloating, abdominal pain and diarrhoea. A randomized, controlled trial found that FMT could successfully improve symptoms of SIBO, as well as reduce gas production. 

Ulcerative colitis                                                                                                      

Ulcerative colitis is a type of inflammatory bowel disease (IBD), where inflammation affects the colon and rectum. This can lead to abdominal pain and diarrhoea, which is sometimes bloody. 

A meta-analysis of six randomized, controlled trials including 324 people found that FMT is helpful to achieve remission in patients with active ulcerative colitis.

Cancer                                                                                                                                                                                                      

Cancer is caused by changes in our genes and DNA. But once formed, cancer cells are clever and find ways to avoid our immune system.  

Immunotherapy is a relatively new type of treatment, which tweaks our immune system cells to attack cancer. Some people respond really well to it, but others don’t. 

Scientists thought it might be helpful to take the gut microbiota of people who responded well to the therapy and give it to the people who didn’t. After all, research shows that our gut microbiota can help to strengthen our immune system response to fighting infections

In 15 patients with melanoma who failed immunotherapy, 6 of them went into remission after repeating the treatment with FMT. Also, they found that FMT reduced the toxic side-effects of the cancer treatment in the majority of patients.  

Whilst there hasn’t been many more studies of FMT in cancer, there are now lots more trials being carried out to determine if FMT can help people respond better to cancer treatment.

Is FMT safe?

A systematic review looked at the safety of FMT trials across 20 years. 

They found that around 1 in 5 FMT procedures resulted in adverse events, although these were mostly mild, such as diarrhoea and abdominal discomfort. Serious adverse events including infection and death were much rarer, in around 1 in 100 FMT procedures, and usually only occur in those with complex medical history. 

All in all, FMT is an exciting prospect for many conditions, but more research is needed before it can be recommended in conditions other than C diff. 

Metabolic syndrome 

Metabolic syndrome is a medical term given to people who have obesity, diabetes and high blood pressure. Studies have shown metabolic syndrome is often associated with a disrupted gut microbiota.  

A meta-analysis of 154 people from six randomized, controlled trials found that FMT showed some promise in improving markers of metabolism in patients with metabolic syndrome, but these improvements were only short-lived. It’s unclear whether there are any benefits beyond 3 months.