TO STAY HEALTHY, KEEP YOUR MICROBES IN LINE

You now know that the human body hosts a variety of microbes, but you might be surprised by the volume.  If the collection of bacteria, fungi and other organisms could be shed all at once, it would weigh 2-4 pounds and fill 1-2 quarts.  En masse, scientists call it the microbiome and have come to believe it is as important to good health as a sound brain, heart, kidneys, liver and lungs.  It helps digest our food, regulate our immune system and feed the cells that line the gut.  But if its mix of microbes gets out of whack, the same organisms that ensure our health can make us sick.  Not only with conditions such as irritable bowel syndrome and inflammatory bowel disease, but cardiovascular disease, and even Parkinson’s, autism and multiple sclerosis.  Remarkably, these illnesses, as well as obesity, have been transferred to mice by implanting the rodents with samples of the microbiomes of humans who suffer from the disorders.  You can take a condition that affects the nervous system or brain and transmit it across species with the microbiome. 

Although there is still much to learn, there is hope that in the future researchers will be able to use the microbiome to treat diseases.  In small studies fecal transplants have been used to successfully treat a hospital-acquired infection know as Clostridium difficile, or C-diff.  The microbiome has also successfully been used to improve the symptoms of autism.  And in controlled studies, researchers can distinguish healthy individuals from those who are sick by examining their microbiomes. 

The first step in understanding the microbiome is to document the assembly of microbes, and each person’s appears to be unique.  This doesn’t rule out the possibility of doppelgangers among the earth’s population, but it’s possible that, in addition to medical therapies, the microbiome could be useful as trace evidence in criminal investigations, just like fingerprints or DNA. 

The microbiome occupies the skin and the body’s various orifices, but it is primarily composed of bacteria that reside in the gut, a constantly changing environment.  Another way of thinking of its size is as a ratio to the number of human cells in the body.  An often repeated but disputed number suggests that there are 10 microbes for every human cell.  Not all the organisms in the human microbiome have been identified, but one of the better known is E. coli, a sometimes-deadly bacteria that provided early evidence that microbes could be beneficial in treating human disease. 

While there is no doubt that reducing pathogens can improve public health, scientists now suspect that in our zeal to avoid infection, we may have separated ourselves from some of the benefits of bacteria.  There is increasing evidence that exposure to healthy microbes in the earth, dust, air and water and on pets is actually good for us.  It’s a whole new way of thinking about germs. 

From an article by Jo Craven McGinty with edits from Dr. Evans