Bringing Up Baby II: The Infant Gut Microbiome and the Risk of Allergies and Asthma
Fascinating new research suggests that breastfeeding benefits babies, in part, because it encourages the growth of the best classes of friendly bacteria in baby’s gut. The switch from breast milk to solid food ushers in dramatic changes in the makeup of these diverse communities living in the digestive tract (the “gut microbiome”). And that may have implications for baby’s future health—or illness.
Given our embrace of antibiotics since their introduction in the mid-20th century, you’d be forgiven for thinking that these drugs can be used safely, with abandon. But aside from the growing problem of antibiotic resistance, which has been attributed to the rampant overuse of these drugs, there’s also the under-recognized problem of how these drugs affect our friendly bacteria.
Ear and other infections are common among infants and young children. As a result, antibiotics are, by far, the most commonly prescribed drugs in this age group. Unfortunately, about one-third of all such prescriptions are now thought to be unnecessary. And emerging evidence suggests that these drugs are far less benign than we previously suspected. Of course, it has to do with the health of the gut microbiome. Many antibiotics are “broad spectrum,” meaning they kill all microbes in the body more or less indiscriminately. That’s inarguably a good thing when you have a life-threatening infection.
But if you don’t, it’s a bit like throwing the baby out with the bathwater. That’s because scientists now think early antibiotic use harms the delicate balance of friendly microbes living in the gut, with far-reaching implications for long-term health. These antibiotic-caused disruptions in the gut microbiome are now thought to affect everything from a person’s future risk of obesity, to allergies, asthma, and even auto-immune diseases, such as type 1 diabetes, or multiple sclerosis.
Antibiotics might affect a child’s risk of developing allergies, for example, by altering the makeup of bacteria that would otherwise have aided the maturation of key immune system cells in the digestive tract. Even if the bacteria in question return, the immunological damage may be too late to repair. Under this scenario, when presented with a potential allergen, the affected person’s immune system essentially responds inappropriately and aggressively. Allergies, are, after all, the result of an immune system that is over-reacting to an essentially harmless substance.
Vangay et al. Antibiotics, Pediatric Dysbiosis, and Disease. Cell Host & Microbe, May 2015 DOI: 10.1016/j.chom.2015.04.006
Fujimura et al. Microbiota in Allergy and Asthma and the Emerging Relationship with the Gut Microbiome. Cell Host & Microbe, May 2015 DOI: 10.1016/j.chom.2015.04.007