Infectious disease specialist Blaser makes an impassioned plea for maintaining the biodiversity of the ecosystem that exists in and on our bodies: the human microbiome.
That microbiome consists of 10 trillion bacteria, fungi and viruses, and it’s a life-support system we depend on to metabolize foods, make vitamins, outcompete pathogens and bolster immunity. Blaser claims that we are killing the system with overuse of antibiotics, hand sanitizers and increased cesarean births, which eliminate babies’ baptism by bacteria as they pass through the birth canal. The result is a shrinking of diversity, shifts in the ecosystem and a dangerous rise in antibiotic-resistant pathogens. The author is no foe of antibiotics; indeed, the drugs once saved him from death from typhoid fever. However, he deplores the all-too-easy reach for the prescription pad to treat nonserious (and nonbacterial) runny noses and colds, not to mention the dosing of farm animals with antibiotics to promote rapid growth and weight gain. Blaser concentrates on gut bacteria—the richest sites of human colonization—and uses the example of H. pylori, ancient acid-tolerant stomach bacteria found only in humans, to demonstrate that bugs can play both good and bad roles in human health. Eliminating H. pylori eliminates stomach inflammation (gastritis), ulcers and late-life risk of stomach cancer, but the species also generates hormones, helps regulate inflammation and modulates immune reactions. Blaser also has epidemiological data and intricate animal experiments to back up associations between antibiotics/changed microbiomes and inflammatory bowel disease, Type 1 diabetes, obesity, some cancers and even autism, with the suggestion that there are critical times in early development when even transient use of antibiotics can have lifelong effects. There’s no denying that the diseases Blaser highlights are multifactorial in origin and that the hygiene-hypothesis folks have a point when they declare our hypersanitized world revs up our immune systems to attack us.
Credit Blaser for displaying the wonders and importance of a vast underworld we are jeopardizing but cannot live without.