Microbes may play crucial role in human health, researchers discovering

Rob Stein

THE WASHINGTON POST

October 10, 2011 ET

Consider this: The average person's body contains about 100 trillion cells, but only maybe one in 10 is human.

This isn't the latest Hollywood horror flick, or some secret genetic engineering experiment run amok.

This, it turns out, is nature's way: The human cells that form our skin, eyes, ears, brain and every other part of our bodies are far outnumbered by those from microbes — primarily bacteria but also viruses, fungi and a panoply of other microorganisms.

That thought might make a lot of people lunge for the hand sanitizer, but that impulse may be exactly the wrong one. Researchers are amassing a growing body of evidence indicating that       

microbial ecosystemsplay crucial roles in keeping us healthy.

Moreover, scientists are becoming more convinced that modern trends — diet, an­tibi­otics, obses­sion with clean­li­ness, Caesare­an de­liv­er­ies — are disrupting this del­icate bal­ance, con­tribut­ing to some of the most perplexing ail­ments, including asthma, al­ler­gies, obesity, dia­betes, autoimmune diseases, can­cer and perhaps even autism.

"In terms of potential for human health, I would place it with stem cells as one of the two most promising areas of research at the moment," saidRob Knight of the University of Colorado. "We're seeing an unprecedented rate of discovery. Everywhere we look, microbes seem to be involved."

Equipped with super-fast new DNA decoders, scientists are accelerating the exploration of          

this realm at a molecular level, yielding provocative insights into how these microbial stowaways may wield far greater powers than previously appreciated in, paradoxically, making us human.

"The field has exploded," said Jeffrey I. Gordon of Washington University, who pioneered the exploration of humanity's microbial inhabitants, known as the "microbiome" or "microbiota." "People have this sense of wonderment about looking at themselves as a compilation of microbial and human parts."

Some equate these microbial inhabitants to a newly recognized organ. Acquired beginning at birth, this mass of fellow travelers may help steer normal development, molding immune systems and calibrating fundamental metabolic functions such as energy storage and consumption. There are even clues that they         

may help shape brain development, influencing behavior.

"The 'human supraorganism' is one term coined to describe the human host and all the attendant microorganisms," said Lita M. Proctor, who leads the Human Microbiome Project at the National In­stitutes of Health, which is mapping this world. "There's been a real revolution in thinking about what that