“Commensal microbes that live on and in us are critical for our health. By cell numbers, we are approximately 90 percent microbial, and the vast majority of the genes expressed in our superorganism are not on our mammalian chromosomes but in the bacteria, archaea, and single-celled eukaryotes that call the human body home. Normally, a robust microbiome would be part of our inheritance, a legacy passed, largely maternally, from generation to generation. But recently that chain has been broken, usually more than once. The increase in cesarean deliveries, the reduced prevalence and duration of breastfeeding, overuse of antibiotics both as prescription drugs and in agriculture, modern urban living surrounded by sanitizers, and a general tendency to limit contact with the environment have changed our relationship with the microbes that are an integral part of our biology. In today’s world, our best chance of acquiring microbes might be from touching our computer keyboards and cellphones or frequenting shopping malls, hotel rooms, or doctors’ offices—and many are not bugs you want in and on your body.” . . .
“Antibiotic administration in infants is associated with higher risk of asthma later in childhood, a risk that scales with the number of rounds administered.11 Increased use of antibiotics in infants is also associated with a higher risk of childhood obesity,12 and some investigations have reported an association between antibiotic use and an elevated risk of celiac disease. It is likely only a matter of time before more links between disease and an infant’s compromised microbiome are revealed.”