There are trillions of microorganisms, including bacteria, fungi and viruses, inside your gastrointestinal tract. You have in your body approximately the same number of organisms, mainly in the large intestine, as in cells. But only 10% to 20% of the gut bacteria are the same as those of other individuals.
Microbiomes differ significantly from person to person, depending on diet, lifestyle and other factors. And they influence everything: health, appetite, weight and mood. But, although it is one of the most researched parts of the body, there is still a long way to go to understand the intestine.
The diet has a significant influence on the intestinal microbiome. Research shows relationships between the Western diet, typically high in animal fat and protein and low in fibre, with increased production of cancer-causing compounds and inflammation. The Mediterranean diet, on the other hand, which is typically high in fiber and low in red meat, has been linked to increased levels of short-chain faecal fatty acids, which have anti-inflammatory effects and improve the immune system.
In the last few years there has been a trend surrounding the health benefits of prebiotics and probiotics. But although they are increasingly used in treatments, including inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, several scientific reviews point to the need for more research on the most effective strains and dosages.
Influence on behaviour
We also begin to understand how intestinal microbes influence behaviour. Some studies, primarily conducted on animals, suggest that certain types interfere with brain chemistry and social behaviour in animals.
On the other hand, germ-free animals, without exposure to microbes, showed deficits in social behaviour, and the researchers found that this can be restored by adding specific types of bacteria, such as lactobacillus, often found in yogurt.