The Human Microbiome


 

 

I have always been excited by a new paradigm. Captivated by its novelty. Intrigued by the realization that what we had previously considered to be self evident and true was not sacrosanct. Immutable. Of course I have to confess that it is often the perspective that interests me: that it sometimes okay to question the consensual adherence to a theory -to question what we have all come to believe is correct. To re-interpret the data.  Consensus establishes nothing; it only demonstrates that that we have been swayed by it. It merely lionizes a viewpoint; it does not validate it. And yet that’s Science: always open to refutation, reassessment. Change. According to Karl Popper -the great philosopher of science- a theory should only be considered scientific if it allows the possibility of being proven false.

I’ve just read a fascinating new book on the microbiome (microbiological contents) of the gut and its influence on our health (Missing Microbes, by Dr. Martin Blaser). Admittedly it’s a topic that is all the rage nowadays, but its previous neglect seems, in retrospect, to defy belief. Of course, since the Germ Theory was proposed in the mid sixteenth century, and since microbes were first observed by Anton Van Leeuwenhoek through his primitive microscope the following century, we have been at odds with them, to say the least. They seemed to be hostile to us. Alien. Their presence caused diseases, suffering, and death. We called them germs. That they could be other than enemies was inconceivable. The only good germ was a dead germ; it was obviously in our best interest to eliminate them. All of them…

And yet if they are so menacing, so evil,  why do our bodies tolerate such a large number of them? Seventy to ninety percent of all the cells in our bodies are not ours -an estimated 100 trillion enemy soldiers hidden in a Trojan horse. And inside our gates… If microbes are bad, why is our large bowel packed with them? Why would we carry around our own sources of disease? How could evolution be so stupid?

It seems blindingly obvious, in retrospect, that they must help us in some fashion. And indeed, the bowel micro-organisms are now being increasingly recognized as extremely useful; so useful in fact that one might be well advised to consider them to be another organ –as important for our health as the liver or the kidneys. It’s becoming clear that they seem to serve as co-directors of many bodily processes – immune functions most importantly perhaps, but also for digestion and production of important nutrients, suppressors of other less-friendly bacterial and viral invaders, and even regulators of energy resources -changes in gut flora may be important in obesity and diabetes, for example. We’re only beginning to understand what role they play in our health, and how altering them can alter us.

But I’m an obstetrician, un accoucheur; I deliver babies; I take care of moms and their foetuses through their pregnancies. I lay no claim to much bacteriological expertise, let alone a privileged view of its cutting edges. But as I mentioned, I was absolutely fascinated by Dr. Blaser’s book -especially the chapters about how we get the first dose of bacteria in our bowels, and how the method of delivery might alter that for good or ill. Obviously at this stage, much of this is speculation -interesting, but as yet largely unproven. But think about it: foetuses in the womb are pretty well bacteria free before they are born. They acquire bacteria only after (or during) birth. On their way down their mother’s vagina they acquire their first micro-organisms: they swallow the lactobacilli which dominate the vaginal bacteria. This helps the baby to break down lactose -the major sugar in its mother’s milk. And given the proximity of the vagina to the anus, the baby also gets its first dose of bowel bacteria -the area is not clean no matter how hard we pretend.

So what happens to the baby’s bowel flora if it never passes through the vagina and is delivered instead by Caesarian Section? Is it different? Is it deficient? And if so, does this have any long lasting effects -either good or bad? I mean, the babies seem to turn out okay…

And what about the customary prophylactic dose of antibiotics that are given preoperatively to prevent maternal infection, or the penicillin (or other antibiotic substitute) that is given to mothers who are intending to have a normal vaginal birth but are positive for Group B Streptococcus (GBS) and in labour? Some of this enters the baby, too; does it alter their bowel bacteria? Is this bad, or do the bacteria recover eventually? Does the interim bacterial alteration, come at a crucial time in the immature but rapidly developing immune system just as the baby is learning to adapt to life and its challenges outside the womb?

The difference is obviously an area that needs more study, but some of the early data are truly intriguing. Researchers have even wondered whether the mode of delivery may alter conditions in the growing child -but later (and so less easily attributable to method of delivery). Things such as asthma, or allergies are exaggerated immune responses -maybe ones not dampened by early modulation by the microbiome. And inflammatory bowel disease, autoimmune dysfunction, and even diabetes may be types of genetic epiphenomena -existing genes turned on or off, dimmed or augmented- altered from an early age and possibly -maybe probably- influenced by the bacteria in the gut …

So, am I recommending we stop doing Caesarian Sections? Stop giving antibiotics? Stop wiping off babies to dry them and help their thermoregulation but also -almost a bonus- to clean them after delivery? Should we abandon all that we’ve accomplished, all that we’ve learned in the last 50 years? No, of course not. But sometimes there are options. Choices. If nothing else, it behooves us to discuss these issues with our patients  -early in their pregnancies, preferably, so that rational conversations, untainted by fear and stress, can provoke dialogue and exploration. There are consequences to every decision. So if an elective Caesarian section is chosen for reasons other than absolute necessity we -patient and doctor- must be apprised of the risks -even the potential, unproven risks of suboptimal microbiomal acquisition…

We are naturally engrossed in the prevailing paradigms -they have served us well and reduced mortality rates; we no longer fear death each time we fall ill. But we have entered an age when an increasing cohort of bacteria are becoming resistant to even the most powerful antibiotics. We need a different appreciation of micro-organisms -a paradigm shift- one that acknowledges that not all of them are malevolent; one that appreciates that they probably do more for us than they do to us. An approach that acknowledges there are far more of them than us and so we should try to use their strength to our advantage. It seems to me that, as members of the current paradigm flock, we’ve almost exhausted the meadow where we’ve successfully grazed for such a long time; we have been so happy with the pasture, so complacently wandering with the herd that we didn’t even notice a gate in the fence to an area where the grass is truly greener and more abundant.

We progress incrementally, but only when our minds are open to new ideas. New perspectives. Truth, it seems, is ever changing, and not always what we want it to be. It can be messy and unbelievable at first -uncomfortable even. But as Einstein once remarked: If you are out to describe the truth, leave elegance to the tailor.

 

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2 thoughts on “The Human Microbiome

  1. Jay Laflamme says:

    A enjoyable read.
    I love your last paragraph!

    Like

  2. Jay Laflamme says:

    An enjoyable read that is . . .

    Like

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