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Microbiota and microbiome: what are they?

These two terms microbiota and microbiome are often used as synonyms, but in reality there are subtle differences between the two.

What are they?

• gut microbiota accompanies the person from birth and influences the function of the whole organism. Until a few years ago, it was called "intestinal microflora."

• human microbiota is made up of a wide variety of bacteria, viruses, fungi and other monocellular organisms that live in the body (intestine, skin, mouth, genitals, etc.)

• microbiome is the name given to all genes within these microbial cells

In 1996, Dr. Rodney Berg of the department of microbiology and immunology at Louisiana State University, wrote a lot about the gut microbiota and summarized its "deep" importance. Therefore, for many years the importance of these bacterial populations for our state of health was known, but not all of them still devote the attention they deserve.

The National Institutes of Health (NIH) in 2007 launched the Human Microbiome Project, a research project that aims to define the microbial species that influence humans and their relationships with the host organism health.

Let's see some data:

• microorganisms that live within the gastrointestinal tract add approximately 4 kilos of biomass

• microbes in the body represent about 2-3% of the total weight of the human body

• intestinal microbiota contains more than 3 million genes, which makes it genetically 150 times more varied than the human body

• each human being has between 10 billion and 100 billion microbial cells (more than cells in the human body) in a symbiotic relationship. This benefits both microbes and their guests

• the estimation vary, but there may be more than 1,000 different species of microorganisms that make up the human microbiota

The gut microbiota of each individual is unique as a fingerprint. It can strongly influence the immune response, digestive function and even mood and psychological processes.

As we said before, every human being has a symbiotic relationship with the microorganisms that live inside their bodies. This symbiotic relationship is beneficial for both humans and microbes. However, these "native" microbes also include harmful bacteria that can overcome the body's defenses that separate them from other districts and vital organs.

In the intestine, there are beneficial bacteria and harmful bacteria that can cause infections when their proliferation exceeds a certain threshold. These infections include food poisoning, other gastrointestinal diseases that cause diarrhea and vomiting or infections in the urogenital tract.

Why is the human microbiota important?

Microorganisms have evolved along with humans and form an integral part of life, performing a series of vital functions.

They are involved in physiological and pathological processes and research has found links between bacterial populations and the following diseases:

• asthma • autism • cancer • celiac disease • colitis • diabetes • eczema • cardiovascular disease • malnutrition • multiple sclerosis • obesity

The human microbiome influences the following four main areas of health importance:

• nutrition • immunity • behavior • disease


In addition to absorbing energy from food, gut microbes are essential to help humans to assimilate nutrients. Intestinal bacteria help us to break down complex molecules of meat and vegetables, without its help, for example, vegetable cellulose would not be digestible.

Intestinal microbes can also use their metabolic activities to influence food cravings and fullness feeling.

The diversity of the microbiota is linked to the diversity of the diet. Adults who try a wide variety of foods show a more varied intestinal microbiota than adults who follow a different dietary pattern.


We all begin to build our microbiome at birth. The first microbes are acquired even during passage in the vaginal canal, at the time of birth.

Without these first microbial hosts, "adaptive immunity" would not exist.

This is a vital defensive mechanism that learns to respond to pathogens after meeting them. This provides a faster and more effective response to possible bacterial attacks that will occur throughout our lives.


The microbiota can affect the brain which also participates in digestion. Some have even defined the intestinal microbiota as a "second brain."

The small molecules released by the activity of intestinal bacteria trigger the nervous response in the gastrointestinal tract.

The researchers also observed links between the intestinal microbiota and psychological disorders such as depression and autism spectrum disorder (ASD).


Bacterial populations in the gastrointestinal system have provided information on intestinal conditions, including inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis. Low microbial diversity in the intestine has been linked to IBD, obesity and type 2 diabetes.

The state of the intestinal microbiota has been linked to the metabolic syndrome. Changing the diet to include prebiotics, probiotics and other supplements has reduced these risk factors.

Intestinal microbes and their genetics influence energy balance, brain development and cognitive function. It is investigating exactly how this happens and how this relationship can be used for the benefit of individual.

The microbiota also plays an important role in the resistance to intestinal proliferation of germs populations introduced from outside (food, oral contamination, etc.) that would otherwise cause alterations. To ensure the right balance, "good" bacteria compete with "bad" bacteria, releasing some inhibitory and anti-inflammatory compounds and preventing them from getting control.

We have long known that taking antibiotics can cause significant dysbiosis and deficiencies of essential bacterial strains for our body with the consequent decrease in the immune response.

Problems such as cystitis, vaginosis, candidiasis, infections resistant to the same antibiotics are on the agenda when the physiological flora is altered or compromised.

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