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.

The gut–brain axis

Western diet, typically high in animal fat and protein and low in fibre, increases the risk of cancer. The Mediterranean diet is high in fibre and low in red meat and has been likened with anti-inflammatory effects and an improved immune system.This leads us to the conclusion that gut health, favoured by fibre, is a reason for longevity of people following the Mediterranean diet.

Western vs. Mediterranean diet

There has been a lot of hype around the health benefits of prebiotics and probiotics in recent years, but while they're increasingly used in treatments including inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis, several reviews suggest there needs to be further research on which strains and dosages are effective. Recent studies have found some people are even immune to probiotics.

Probiotics

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.

Antibiotics and gut health

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.

Gut microbiota

Inside your gastrointestinal (GI) tract are trillions of micro-organisms, including bacteria, fungi and viruses. You have roughly the same number of micro-organisms in there, mostly in the large intestine, as you do human cells in your entire body. But only 10% to 20% of the bacteria you have in your gut will be shared with anyone else.