Microbiota and Gut Microbiota Diversity

- Overview

Gut microbiota diversity refers to the diversity of microorganisms in the gut, including bacteria, fungi, and viruses. A diverse gut microbiome is generally considered healthier because it makes the microbiota more resilient and capable.

Factors that influence gut microbiota diversity include:

• Diet and lifestyle: Diet and lifestyle patterns are the biggest factors that influence the variety of bacteria in your gut.
• Age: Gut microbial diversity typically decreases as people age.
• Social interactions: People with larger social networks tend to have more diverse microbiomes.
• Anxiety and Stress: Anxiety and stress are associated with reduced diversity.

Decreased diversity is associated with chronic diseases such as obesity and type 2 diabetes. To restore diversity, fecal microbiota transplantation has been proposed.

The intestinal microbiota provides the necessary capabilities for the fermentation of indigestible substrates such as dietary fiber.

- Diet and Gut Microbiome

We all have a collection of bacteria, viruses, fungi, and other microbes living inside us, collectively known as the microbiome. These microbial populations vary from person to person, as well as from organs and systems such as the skin, mouth, respiratory tract and (most importantly) the gut. 

The microbiome remains relatively stable throughout the life of an organism, although diet is a key factor in maintaining it. As early as 1919, John C. Torrey explained, "It is now well known that diet has a profound effect on determining the types of bacteria that grow in the gut." Microorganisms in the gut depend on their host for nutrients because they The end products left after digestion are metabolized to produce various secondary metabolites. 

Changes in microbial composition are associated with fluctuations in our immune, metabolic and neurobehavioral health. As a result, the field of gut microbiome research has attracted considerable attention because these microbes and their metabolites can affect health and disease elsewhere in the body.

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- Gut Bicrobiota Diversity

Gut microbiota diversity corresponds to the number of different species present in an individual. There is every reason to believe that the diversity of gut microbiota is an indicator of the microbiota’s good health. Indeed, when observing gut microbiota among people with non-communicable diseases (cardiovascular diseases, cancers, chronic respiratory diseases and diabetes) and the elderly, researchers realised that these individuals’ microbiota were poorly diversified. 

Paul Cotter (Teagasc Food Research Centre and APC Microbiome, Ireland) compares a diverse gut microbiota to a tropical ecosystem in which a variety of trees, plants, birds and other animals peacefully coexist. “A rain forest is like a highly diverse microbiota in that there are lots of different species that can do lots of different things. Even if one of these rain forest species dies, the overall environment will continue to thrive”. 

In contrast, a forest with only few summer plants and trees will be weaker and less able to survive when winter arrives. Compared to the rain forest, the summer forest is less diverse and rich and, as a result, less resilient.

Recently, scientists have shift from the number of microorganisms to the number of gut microbiota genes as an accurate way to predict how healthy your gut microbiota is. This means that the richer your gut microbiota gene count is (i.e. high species diversity capable of doing a wealth of functions that humans cannot exert themselves), the more resilient your gut microbiota will be. 

According to Paul Cotter, a high degree of microbial diversity is not only desirable in humans but also in other species (cattle, pigs, horses, fish, insects, etc.), in the environment (soils, waste treatment plants, etc.) and even in fermented foods. This is why the slogan chosen for #WorldMicrobiomeDay 2020 is #DiversityMatters. This is the main topic that integrates both microbiota and the means and advice through which their diversity can be maintained.