“In the Gut: The Mix of Bacteria Can Affect Weight” by Melinda Beck. The Wall Street Journal, 11/18/2014.
“On the Subway, Scientists Track the City’s Secret Life of Germs,” by Robert Lee Hotz. The Wall Street Journal, 2/6/2015.
A recent study of New York City’s subway system found the DNA of over 15 thousand life forms; about half were species of bacteria, and 67 were known causes of illness. We shed about 1.5 million skin cells every hour, and these can quickly spread the bacteria, quickly enough to colonize a hotel room in less than six hours. No place is safe. Mama was right to make us wash our hands before eating.
We are all born free of bacteria, but soon develop colonies that contain about 100 trillion of them, about ten times the number of our own cells. Step on a scale, and they add about five pounds to our weight. They cover every inch of our skin, our mouth, our nose, our ears, our eyes, and particularly our gastrointestinal tract. Medical professionals are increasingly seeing us as a walking ecosystem of bacteria colonies, a microbiome. We are a minority party in the democracy of our own bodies.
The bacteria not only help digest food, they repel invaders and produce chemicals that help regulate the immune system, metabolism, and even mood. Disturb the colonies at your peril.
“In the past, most bacteria we saw were the nasty guys, the ones that kill you. We haven’t been looking at the thousands of nice guys that help us and keep us thin,” says Tim Spector, a genetic epidemiologist at King’s College, London.
Keep us thin? An emerging theory is that the apparent genetic factor in body weight is actually a genetic propensity to cultivate one strain of bacteria in our gut that helps stimulate metabolism. The root cause of obesity could come from world-wide overuse of antibiotics that disrupts such colonies. If this is proven, perhaps the bacteria could be induced artificially, such as by a fecal transplant (see the February 16th posting).