Gut microbiota and how it influences your health

Let's finish the week with a little bit of info about gut microbiota and why it is becoming a trending topic.

Animals have clusters of microorganisms living on and inside their bodies, in mostly all parts of the body, such as in the surface or deep layers of skin (skin microbiota), the mouth (oral microbiota), the vagina (vaginal microbiota), and so on. Gut microbiota (formerly called gut flora) is the name given to the microbe (bacteria, virus, fungi and protozoa) population living in our intestine. Even we have always believed that microorganisms are bad for our health and we should avoid them, that is not true. There are good and bad microorganisms, all of them sharing an enviroment (our body). Which is real important is the balance between the good and the bad bugs.

Our gut microbiota contains ten of trillions of microorganisms, including at least 1000 different species of knowm bacteria with more than 3 million genes (150 times more than our genes). We should remember that each gene is responsible of one specific biological function, so bacteria can do a lot of different functions. Why our microbiota has been recently described as our hiden organ, able to carry our many biological functions. Our microbiota can, in total, weigh up to 2 kg. One third of our gut microbiota is common to most people, while two thirds are specific to each one of us. This means that the microbiota living inside your intestine is like an individual identity card. 

Although gut microbiota can be found in all the different organs of the digestive tract (from the mouth to the large intestine), it is true that the last part of the small intestine and the colon are the areas that harbour the highest concentration of microorganisms. 

And why is the microbiota so important? Because as we have mentioned before, the microbiota is in charge of fullfil a lot of physiological functions, with a final direct impact on our health. Some of the functions are:

• It helps the body to digest certain foods that the stomach and small intestine have not been able to digest (i.e. lactose or dietary fibre).
• It helps with the production of some vitamins (B and K). 
• It helps with the production of important molecules for our health, like serotonin, a neurotransmitter also known as the hormone of wellbeing and hapinness. 
• It produces some compounds that we need but we are not able to synthesize ourselves, such as short chain fatty acids (acetate, propionate and butyrate). Butyrate is the main fuel of our gut cells, indeed, and without them the cells can not renew themselves properly.
• It helps us combat the aggressions from other microorganisms coming from outside our body and from pathogenic microorganisms (able to cause diseases). They are like our particular mini army.
• It plays an important role in the immune system. During early life, the microbiota shapes the development of the immune system and how it will work later in adulthood. This relantionship between the microbiota and the immune system during childhood is crucial.

A healthy and balanced gut microbiota is key to ensuring proper digestive functioning. 

Taking into account the major role gut microbiota plays in the normal functioning of the body and the different functions it accomplishes, experts nowadays consider it as an "organ". However, it is an acquired organ, as babies are born sterile. The colonisation starts right after birth, evolve as we growth and relies on many different aspects (the mother microbiota, the delivery mode, the environment, the diet, the use of antibiotics in early life...).

The newborn's digestive tract is quickly colonised by microorganisms from the mother (vaginal, faecal, skin, breast, etc.), the environment in which the delivery takes places, the air, etc. From the third day of life, the composition of the microbiota is directly dependent on how the infant is fed: breastfed babies have got a microbiota mainly dominated by Bifidobacteria (present in the milk), compared to babies fed with infant formulas. Scientits consider that by the age of 3 years old, the microbiota becomes pretty stable and similar to that of adults, continuing its evolution at a stadier rate throughout life.

Gut microbiota balance can be affected during the ageing process and, consequently, the elderly have substantially different microbiota composition to younger adults. 

While the general composition of the intestinal microbiota is similar in most healthy people, the different species of microorganisms present in the microbiota is highly personalised and largely determined by our environment, our lifestyle and our diet. The composition of the gut microbiota has evolved with the diet in different populations. Japanese people, for example, can digest seaweeds (regular part of their diet) thanks to specific proteins that their microbiota has aquired from marine bacteria. It is worthy to mention than even small temporarily changes in our diet can impact on the composition of our microbiota. 

These changes in the microbiota composition can lead to a loss of balance in gut microbiota. This situation is generally known as dysbiosis. Change in diet is not only factor leading to dysbiosis. The consumption of antibiotics and other drugs, health problems such as functional bowel disorders, IBD, allergies, obesity and diabetes, can also lead to dysbiosis.

Many studies have demonstrated that the balance in our gut microbiota can be restored thanks to the beneficial effects of prebiotics and probiotics. Prebiotics are compounds that serve as "food" for beneficial bacteria, such as fibre. On the other hand, probiotics are live beneficial bacteria. Probiotics are present in some fermented food such as yoghourt, kefir, kimchi, sauerkraut, tempeh or kombucha; or in supplements. Both prebiotics and probiotics help to keep microbiota balance, integrity and diversity.

Thanks to scientific investigation, the picture of the bacteria living in our gastrointestinal tract is becoming clearer. Researchers now use a range of techniques to further clarify the mysteries of microbiota. While there are still some things that are yet to be discovered, more and more findings are being presented every day.

I hope you have enjoyed this publication and see you soon!!

Sonia