Monday, February 25, 2013

You Really Are More Than the Sum of Your Parts

“And do you floss regularly?”
Once years ago, a different dentist asked me this question and I said “no.” He looked surprised. I added “or do you want me to do what most of your other patients do and say ‘yes’ even though I don’t?”
This time it was a dental technician. But I still said “no.” 
She was ready for that answer. She turned me in my chair toward a small TV screen where I could see the bacteria from my mouth swab, magnified and bustling around, presumably wondering where my mouth had gone. 
“There - look at all the bacteria that came out of your mouth. This helps lots of people understand why it’s so important to floss their teeth.”
I smiled at her. “But which of those are the bacteria that help me break down the food I eat? The good bacteria? If you can point out which are the bad ones I’m supposed to be flossing away, that would be great.”
Now there may be very good reasons to floss one’s teeth. But ridding the mouth of bacteria isn’t one of them.
Most of us know we have colonies of good bacteria living inside our bodies. I learned in school, even way back in the 1970’s, that without our gut bacteria we would not be able to break down what we eat into fuel our body can use. But there are also ‘bad’ bacteria, the ones antibiotics were created to seek and destroy. Unfortunately, dropping antibiotic bombs into our bodies causes the same sort of collateral damage as dropping bombs onto populated areas during wartime. Antibiotics may wipe out a dangerous infection in our bodies, but we also wipe out a lot of good bacteria at the same time. 
But if we take probiotics, even just eat yogurt with live cultures, we are told, we can replace the good bacteria while our antibiotics are wiping out the bad stuff. Job done.
Or so we thought.
Science is now starting to discover that the world of human body bacteria is at least as complex as the world of human beings. And, also like human beings, not all bacteria can be divided into ‘good’ and ‘bad.’ In fact, science is at such an early stage in the understanding of this complex system that one hesitates to use those black and white words in relation to any bacteria, yet.
Enter the human microbiome, defined as ‘the complement of bacterial passengers carried around by every human being’ (The Economist, ‘Sniffing Out Hypertension,’ 2/16/13). 
In the New Yorker article “Germs Are Us” (10/22/12), author Michael Specter states:

We inherit every one of our genes, but we leave the womb without a single microbe. As we pass through our mother’s birth canal, we begin to attract entire colonies of bacteria. By the time a child can crawl, he has been blanketed by an enormous, unseen cloud of microorganisms—a hundred trillion or more. They are bacteria, mostly, but also viruses and fungi (including a variety of yeasts), and they come at us from all directions: other people, food, furniture, clothing, cars, buildings, trees, pets, even the air we breathe. They congregate in our digestive systems and our mouths, fill the space between our teeth, cover our skin, and line our throats. We are inhabited by as many as ten thousand bacterial species; these cells outnumber those which we consider our own by ten to one, and weigh, all told, about three pounds—the same as our brain. Together, they are referred to as our microbiome—and they play such a crucial role in our lives that scientists like Blaser have begun to reconsider what it means to be human.
Martin J. Blaser is the chairman of the Department of Medicine and a professor of microbiology at the New York University School of Medicine. The bacterium he studies is Helicobacter pylori, or H. pylori, which was discovered to cause ulcers and contribute to stomach cancer. A campaign was immediately mounted to eradicate it. But Blaser contends that just because it is capable of doing harm, that does not mean it doesn’t have a vital role to play in healthy bodies.  We have learned that removing predators from ecosystems can cause disastrous results for the system as a whole, often in unexpected ways. Could the same be true when we remove potential predators from our internal ecosystems - our microbiomes?  Blaser’s research is continuing, but already he has discovered positive roles that H. pylori plays in the human bodies it inhabits. In fact, studies are linking the destruction of bacteria within our bodies to such varied illnesses and disorders as obesity, Crohn’s disease, and asthma. Bacteria may be an important factor in the regulation of blood pressure (The Economist, ‘Sniffing Out Hypertension,’ 2/16/13). Twin studies in Malawi are producing strong evidence that having the ‘wrong’ gut bacteria can predispose those individuals to malnutrition, even when they consume the same diet as their twins who carry a different bacterial load. (The Economist, ‘Debugging the Problem,’ 2/2-8/12). 
‘Germs Are Us’ author Specter says about bacteria:
Most reside within the gut, but many also occupy our mouths, and one particular bacterium, Streptococcus mutans, has been recognized as the principal cause of tooth decay. When you eat sugar, S. mutans releases acid that corrodes the teeth. Many researchers who study the microbiome now look upon cavities as an infectious disease, and they are testing a mouthwash that kills S. mutans; if it works, dental cavities could vanish.
There are cases where illnesses and infections in one individual have resisted all conventional medical treatments, then have been cured by the transferral of a particular bacterial colony from a healthy individual into the sick one. In one case, described in ‘Germs Are Us,’ a man with a serious chronic infection in one ear cured himself simply by transferring ear wax - and its bacteria - from his healthy ear into the infected one.
So should we all be taking probiotics, maybe all the time? The current scientific thinking is that we still know so little about the bacterial makeup of our bodies - and that makeup varies from individual to individual - that taking a broad-spectrum probiotic may be almost as unwise for some people as taking a broad-spectrum antibiotic. Studies on some widely used probiotics have shown that they can cause or increase some health conditions in some individuals. We don’t know enough yet to identify what is ‘good’ and what is ‘bad.’ And it may turn out that our bacteria, like the people on which they colonize, are often shades of grey.