Gut microbiota has a major role to play in the health and function of the GI tract, with evidence that conditions such as irritable bowel syndrome (IBS) often coincide with altered microbiota. But it also plays a much wider role in our health, and this is largely determined in the first few years of life.

Antibiotics can dramatically alter our gut microbiota. Many of the genes thought to be fixed in certain bacterial environments can start spreading by overuse of antibiotics, which can put pressure on the resistant genes locked up inside a single bacterial cell, causing them to mobilise.

The brain and gut have a strong, two-way communication system Each are essential to the other – studies have found that brain development is abnormal in the absence of the gut microbiome. Gut microbes can produce most of the neurotransmitters found in the human brain, including serotonin, which plays a key role in regulating mood.

 However, research hasn’t yet figured out which exact gut bacterium are crucial for brain development.