Taking just a single course of antibiotics can damage the healthy bacteria in the gut for at least a year and possibly permanently, scientists have warned.

Researchers at University College London (UCL) found that just one prescription can change the composition of the microbiome - the collection of trillions of bacteria, fungi and microbes, which live in the body and help regulate the immune system, aid digestion and produce vitamins.

In a healthy human gut there are around 1,000 different kinds of bacteria in the gut, and greater diversity of species has been linked to better health.

But the new study found that antibiotics caused the gut microbiome to change to a less diverse state with fewer types of bacterial species, potentially raising the risk of disease.

In recent years problems with gut bacteria have been linked to obesity, the development of Parkison’s disease, Crohn’s disease, asthma, allergies, inflammatory bowel, diabetes, multiple sclerosis, autism, cancer, and even HIV.

“People have known that antibiotics decrease the diversity of microbes in the gut before it recovers, but the model we’ve developed suggests that the disturbance may transition the microbiome to a new composition, perhaps permanently,” said first author Dr Liam Shaw, of UCL Genetics Institute.