Microbiota changes throughout life - an overview

Abstract

Over the course of human evolutionary path, our microbiota has co-evolved to achieve a solid relationship with the human host in various body sites. The most densely populated site is the distal gut and gut microbiota is responsible for many utterly important functions that differ throughout life to meet physiological needs at different ages. A trajectory of microbial development tightly follows that of the human host, with initial unstable and rapidly changing microbial communities that are gradually transformed into a stable microbial ecosystem. During the first years of life, environmental and intrinsic factors affect the microbial assemblage, which when unfavorable may induce microbial dysbiosis and consequently alter the immune system maturation and neurodevelopment. Although adulthood is characterized by long-term stability of the gut microbiota with greater resilience to stressors, profound detrimental factors may lead to alterations in microbial communities. Recently elucidated bidirectional connections between the gut microbiota and distal organs, highlight the association between dysbiosis and the onset of various non-communicable diseases. With emerging evidence showing the importance of diverse and rich microbial communities in maintaining homeostasis and health, gut microbiota appears as a novel highly potent therapeutic target to alleviate ongoing pathophysiological processes and further promote longevity. In this article the characteristics of gut microbiota across human lifespan are discussed, with additional reference to microbiota of ancient and rural societies, with an intention to gain a broader picture and to provide insight into the factors influencing microbial assemblage.