Gut microbiome - Our life partner, for better or worse?

Abstract

Trillions of bacteria are living in our bodies and implementing mutualistic functions to us. The gastrointestinal tract alone houses more than 1014 bacteria. One of their known functions is to promote energy extraction from our diets, thereby allowing us to better utilize our food source, particularly in nutrient-scarce environments. This function plays an important role during pregnancy when extra nutrients are needed for the development of the fetus. [Before birth] Substantial changes in the bacterial pattern in the gut have been found in pregnant women from the 1st to 3rd trimesters. This kind of commensalism remains despite the agricultural advances in that have led to a stable nutritional supply, which implies some additional functions of the gut bacteria in pregnancy. Due to the advance of medicine, now we have choices in the modes of delivery. However, cesarean section-delivered babies have a higher risk to develop certain metabolic and autoimmune diseases in early childhood. [At birth] Such risk is related to the differences in bacteria colonization upon different modes of delivery. [After birth] During adulthood, our diet and external environment can substantially change the gut microbiota. Many animal models have proven the effectiveness of fecal transplantation to reverse several diseases, implying the therapeutic potential of altering gut microbiota. However, bed-translation remains limited due to the complicated bacterial ecology and cross-species interaction with host. Investigation from the very beginning of life will help us gain a full picture of how we interact with these commensal microorganisms, thus affecting our health.