Could the answer to a number of modern ailments be in our gut?
By Martha Rosenberg
March 5, 2014
Do you remember the “hygiene hypothesis” of the late 1990s? It theorized that humans had so over-sanitized their environment with disinfectants and hand cleansers, our immune systems were no longer doing their jobs. So many consumer products like toothpaste, hand and dish soap, laundry detergents and even clothes now include antibiotics, said the theory, we seldom encounter the “bad” germs our immune systems are supposed to recognize and fight.
Since the hygiene hypothesis surfaced, there is growing evidence of its truth. In fact the theory that certain medical conditions, especially autoimmune ones, may be caused by a changing or declining bacterial environment in the human gut is gaining momentum and now called the “disappearing microbiota hypothesis.”
The bacteria in our gut, collectively called our microbiome, is a huge, ever-changing universe of billions of microbes. Each person’s intestinal ecosystem is so individualized and such a reflection of his unique inner and outer environments, “gut microbiota may even be considered as another vital human organ,” says one scientific paper. The microbiome has also been called a second genome and even a second brain.
Most people know that taking antibiotics can change their microbiome by killing off the “good” bacteria with the bad. That’s why antibiotics can cause diarrhea and many clinicians recommend taking probiotics with them. But what scientists are just beginning to learn is microbiomes are also affected by their outside environment including influences like house dust and even aerosolized matter when a toilet is flushed. They are also learning that gut bacteria is highly adaptive and one person’s gut bacteria will take root and flourish in another’s intestines. This explains the growing popularity of “fecal transplants” (yes, you read that right) between people who have been depleted of “good” bacteria and donors with healthy populations of microbes in their intestines.
Still, the most astounding research that is developing around the microbiome is the ability of our gut bacteria to affect our brain and “influence our mood and temperament,” says food expert Michael Pollan. “If you transplant the gut microbiota of relaxed and adventurous mice into the guts of timid and anxious mice they become less stressed and more adventurous.”