Two Stories Today…For the Price of One! Stressed You and Overfed You = Stressed And Overfed Gut Bacteria

Two incredibly cool news stories came out last week and since I can’t decide which to share with you today…I’ll share both.

Story 1:

As you all know, if you regularly read this blog, the exact cause of the current inflammatory epidemic plaguing those of us in the industrialized world is unknown.  We do know that alterations of the human intestinal organisms (biome) IS an issue though, and may well be the main culprit.  That fact is now commonly accepted.

There are different hypotheses that explain the cause of the biome differences:  biome depletion caused by excessive hygiene (i.e. lack of exposure to our normal organisms), the overuse of antibiotics, diet differences, and so forth.  A new, very compelling, idea has just been forwarded by researchers at Kiel University, in Germany:  “The Kiel researchers suggest that an unnatural and particularly comprehensive nutrient supply decouples bacteria from their host organisms, and thus destroys the delicate balance of the microbiome. The, to some extent, over-fed bacteria in the gut thus promote disease development.”[i]

That is:  when you overfeed your gut bugs, they no longer need to eat their normal diets – things produced by you, like metabolites, for example.  They can very happily survive and, in fact overgrow, on the excessive nutrients you are consuming.

These scientists noted that research has shown that it’s not just climate change or overfishing that is killing off coral reefs and algae:  it is the nutrient content of the seawater itself.  “As soon as there is an oversupply of food due to human influences, bacteria living in a community with corals begin to decouple from their hosts. They then no longer feed off the metabolic products of the host, but prefer the richer nutrient supply of the surrounding waters. The balance of the coral microbiome is disrupted…and diseases occur as a result.”

This parallels what we are seeing in humans:  “The nutrient supply in the human gut is also changing along with the civilization-induced changes in eating habits – towards an unbalanced, energy-rich [ie. high calorie] and low-fiber diet. In addition to direct negative health consequences, a permanently high, easy to process supply of nutrients not only affects the human metabolism it feeds, but also the bacterial colonization of the intestine, which is also ‘fed.’”  What has, unfortunately, become an all-too-typical  diet in the industrialized world is not just directly harming our health – it’s harming the health of our gut microbes.  And that, of course, indirectly harms us even further.  Says one of the scientists from Kiel:  “This over-feeding of the bacteria promotes their growth as a whole, and certain species of bacteria proliferate to the detriment of other members of the microbiome in an increased and uncontrolled manner.”

In the not-very-distant human past, food was not readily available as it is for us now.  Periodic fasting was the norm.  To boot, people got GI diseases causing diarrhea more often (from bad food, water, etc.)  Bacterial overgrowth was  kept in check by the circumstances of our lives.  That has all changed…as have our gut bacteria.

Interestingly, even before this research was published, the idea of periodic fasting has gained a great deal of traction in the health community.  It has been shown to reduce inflammation…and perhaps now, we know, in part why that may be so.

2^nd story:

Researchers from Bar Ilan University in Israel just published a really interesting paper that shows that high levels of stress not only affect our health directly (i.e. we produce pro-inflammatory cytokines, for example), but directly change our gut bacteria so that they, in turn, stimulate our immune systems increasing “the likelihood that the body would attack itself”…as in autoimmunity.[ii]

The researchers compared the gut bacteria of two groups of mice:  the controls led normal lives.  The experimental group was subjected to daily extreme stress by being threatened by a dominant and aggressive mouse.  After 10 days, the bacteria of the stressed mice had changed:  they had higher levels of various bacteria, including two kinds that are known to be higher in people with multiple sclerosis.  More than that, the bacteria in the stressed mice expressed genes related to “potentially violent traits:  “Microbes with these traits can travel to other parts of the body, including lymph nodes, and elicit an immune response.”  Being subjected to violence led to increased “violence” on the part of the gut bacteria!

And more that: “When the researchers analyzed the lymph nodes of stressed mice, they found an increased abundance of several known pathogenic bacterial species. They also found a higher percentage of effector T cells known to play a role in autoimmunity.”

The gut bacteria not only tipped toward diseased-causing species but some of these “violent” bacteria make their way into your lymph system, which evokes an inflammatory immune response leading to autoimmunity.

Incredible, right?

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[i] https://www.news-medical.net/news/20190516/Over-fed-bacteria-in-the-gut-promote-disease-development.aspx

[ii] https://www.eurekalert.org/pub_releases/2019-05/asfm-hsb051019.php