The Complicated H. Pylori

The Complicated H. PyloriDr. Martin Blaser is one of the experts interviewed by Michael Pollan for his very comprehensive overview of the microbiome, “Some of My Best Friends are Germs.” This is Pollan’s description of one of Dr. Blaser’s fundamental theories:

According to the “missing microbiota hypothesis,” we depend on microbes like H. pylori to regulate various metabolic and immune functions, and their disappearance is disordering those systems.

When groups of people stayed on the same patch of land and ate the same foods for untold generations, the various bacteria that colonize humans had plenty of time to work out their differences, not only with their hosts, but amongst themselves. Over tens of thousands of years, we humans and our microbiota devised compromises and maybe even negotiated Mutual Assured Destruction pacts, but somehow people and internal bugs arrived at symbiotic relationships that served everyone and harmed no-one.

Then, along came antibiotics, and the microbiome was undeservedly under attack. Sure, antibiotic therapy has saved massive numbers of lives and prevented enormous suffering—but at the same time, it has hurt our helpful and necessary tenants. Pollan continues:

Each generation is passing on fewer of these microbes,” Blaser told me, with the result that the Western microbiome is being progressively impoverished. He calls H. pylori the “poster child” for the missing microbes…Medicine has actually been trying to exterminate it since 1983, when Australian scientists proposed that the microbe was responsible for peptic ulcers; it has since been implicated in stomach cancer as well. But H. pylori is a most complicated character, the entire spectrum of microbial good and evil rolled into one bug.

But wait! If H. pylori causes ulcers and cancer, why would we want it around? As the last three Childhood Obesity News posts have suggested, H. pylori has relationships, connections, or links with diabetes and the metabolic syndrome, inflammation,  allergies, asthma, appetite, auto-immune diseases, neurosteroid production, and even depression and other forms of emotional ill health, all of which are connected with obesity in ways that are sometimes tenuous but increasingly un-ignorable. So why would anyone care if this ornery bacteria is eliminated?

That is where the problem lies. We don’t know how much we should care, or to what degree we should welcome H. pylori, or how hard we should actively try to extirpate it. Sure, we have figured out that it “first subverts innate immunity and then modulates the adaptive immune system.” But how mad at it should we be? A report by researchers Amin Talebi and Bezmin Abadi says:

Determining whether H. pylori is beneficial or detrimental in human stomach has been a challenging area of research in gastroenterology…Undoubtedly, we need to eradicate virulent H. pylori in people with adverse clinical manifestations, but this conclusion cannot be generalized to all H. pylori positive subjects…In the end, with continuing current approach against H. pylori, we will lose this old ancient member of our microbiota; an event, which we are not fully aware of its drawbacks.

Presently, scientists are aware of many links, connections and correlations—but not which way causality runs, or who is helping whom, or what would happen to the human race if we managed to wipe out all the H. pylori. For instance, at least one study has pinpointed cognitive development as an area of concern, because kids with H. pylori performed worse on IQ tests.  But so many variables are involved in testing IQ, to draw any firm conclusions would be madness. Skill in taking IQ tests is just one of hundreds of possible areas where H. pylori might affect us adversely. Or positively. Or, because the world is rife with meaningless correlations, not at all.

In the microbiome, apparently the balance of populations is the key thing. It is not only a matter of which bacteria inhabit the GI tract, but their proportions. For instance, experiments with lab animals showed that fat mice had less diversity of species within their microbiomes. Further, the ways in which the various species suppress or potentiate each other are not known. We know that synergy is vitally important, but not how it works, which is why charting all the relationships will be a monumental task. There are a zillion different kinds of microscopic creatures, but because they tend to play more than one role, depending on what else is happening, they can’t even be conveniently sorted into “good bugs” and “bad bugs.”

Your responses and feedback are welcome!

Source: “Some of My Best Friends Are Germs,” MichaelPollan.com, 05/15/13
Source: “Helicobacter pylori: A Beneficial Gastric Pathogen?,” NIH.gov, 08/25/14
Source: “Gut Bacteria May Exacerbate Depression.” ScientificAmerican.com, 11/01/13
Image by opensource.com

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