Bacteria, Digestion, & Immune Function

When most people think of bacteria, they usually think of the kind that spoil your food, taint your water supply, and make you sick. While it is important to understand these organisms and how to avoid them, the fact is that bacteria is all around us, all over us, and even INSIDE us ALL THE TIME. Don’t be grossed out. The good news is that most bacteria is actually good for us and in many instances essential to our functioning and survival.

Good bacteria is important for basic digestion function, and dysbiosis (increased levels of bad bacteria) is well documented to be a significant part of many digestive disorders. Good bacteria on your skin and in mucosal membranes (i.e. mouth/throat, vaginal tract, urethra, etc.) are critical in fighting off infectious bad bacteria. The digestive bacteria is also important in maintaining hormonal balance. Some studies show that the bacteria may even produce androgenic hormones like testosterone. Good (or bad) bacteria is also passed to a baby during childbirth as the child is pushed through the vaginal canal.  This is why it is even more important to build a healthy flora during pregnancy. Dysbiosis is known to cause conditions such as preeclampsia, rupture of membranes leading to premature births, and is also the cause of Group B Strep.

Furthermore, the gut (digestive tract) and brain have a steady ability to communicate via the nervous system, hormones, and the immune system. Some of the microbiome can release neurotransmitters, just like our own neurons do, speaking to the brain in its own language via the Vagus nerve. This interaction is fairly complicated but Dr. Emily Deans at Psychology Today explains it well:

To have a full understanding of how the whole gut-brain connection works, you need robust knowledge of endocrinology, immunology, pathology, and neurology, which is a bit beyond the scope of a blog article. However, to break it down to simplistic terms, here are the basic links:

1) The body responds to stress (mental or physical) via the hypothalamic-pituitary-adrenal axis. For example, if you are eating lunch and a lion jumps into the middle of your picnic table, your “fight or flight” system is fired into full gear, your heart pounds, your pupils dilate, your hair stands on end, natural steroids and adrenaline flood your system to strengthen your muscles and give you an extra burst of speed. Even your platelets change shape so they are more sticky, leaving you less likely to bleed out if you are attacked. Naturally, our bodies have negative feedback that can tone down the fight or flight response once the danger is past (assuming you survive). Under conditions of chronic stress, however, mental or physical, the feedback tends to get messed up, leading to symptoms of chronic stress (which includes mental issues such as anxiety or clinical depression, but also physical problems such as chronic gut problems, headaches, high blood pressure, etc.). What does all of that have to do with the gut?

2) While the hormonal system that regulates fight-or-flight, rest-and-recovery, and everything in between is easy to conceptualize, the second underlying system, the immune system, is far more complex and works at a cellular level. Our bodies aren’t particularly sophisticated when it comes to facing off against stress. Our stress response doesn’t readily distinguish between mental and physical distress; your heart pounds and you tremble with anxiety when you are in an uncomfortable meeting with your boss, when such a reaction is not helpful in that situation, though it might have helped with the lion. And not only to we respond to the tough day on the job with a hormonal response, but also an immunological one. When our body is under stress, it releases what are called inflammatory cytokines, little chemical messengers that bring a certain part of our immune system into high alert. In a sense, our body reacts to all stress as if it were an infection, and to chronic stress as if it were a chronic infection.* Now the immune system works wonders and inflammation saves your life nearly every day from all the pathogens out there like the flu and strep, but chronic levels of inflammatory response also lead to all sorts of chronic disease, for example depressive disorders, high blood pressure, atherosclerosis, autoimmune diseases such as ulcerative colitis and multiple sclerosis. Immune system activation can also determine whether or not we develop cancer. Where does the gut get involved? Well, it turns out the gut microbiome plays a key role in regulating our immune response. Thus the make-up of our gut microbiome could make the difference as to whether we are sick or well, both mentally and physically.

3) Animal and human studies support the theory that pathogenic bacteria in the gut, such as C. Difficile, or in certain circumstances, H. Pylori, lead to human disease, and not just the obvious direct illnesses, pseudomembranous colitis (link is external)and ulcers. These bacteria also interact with the immune system in the gut to cause the release of inflammatory cytokines, stress steroids, and a systemic stress response (similar in most ways to the lion attack). Some of the responses of the gut even have an effect on our pain response…yes, people with certain unfavorable gut bacteria might be more sensitive to pain than others. However, other commensal organisms in the gut seem to have the opposite effect, the most studied being certain strains of Bifidobacterium and Lactobacillus. The right sort of commensal bacteria keep the numbers of pathogenic bacteria low, and also interact with the immune system in a way to turn off that chronic stress response. The  “right” gut bacteria also interact on a hormonal level, helping to turn off the cortisol and adrenaline response that can cause long-term harm to the body. However, each large group of gut bacteria (and Archaea, which have a big influence on digestion and help us ferment and breakdown otherwise indigestible plant fibers) have many different strains, and each of these strains may have differential effects, some of them synergistic or antagonistic. The scope of complexity of the problem is mind-bending. In general, it is felt that more variety in the gut microbiome is probably better, and studies of hunter-gatherers show us they seem to have both more mass and more variety of gut bacteria than do modern Westernized humans.

How can you boost your healthy bacteria?

Here are some simple tips:

  • You are what you eat… and you are the microflora (bacteria) that you feed. Eat foods that nurture your microbiome: don’t eat toxins; eat fermentable fibers – starchy vegetables such as sweet potatoes – they are microflora food; eat fermented foods – kefir, kombucha, sauerkraut & other fermented veggies, etc. – they provide probiotics. Dietary probiotic foods may also assist with balancing vaginal microflora.
  • If your gut is damaged heal it and restore the balance of microflora. This may involve taking probiotic .
  • Minimize stress. Stress messes with your gut microflora and mother’s may pass on the effects of stress to their baby via bacteria. Perhaps prenatal care should involve reassuring words and a relaxing massage rather than constant clinical testing and frequent discussions about risk?
  • Avoid antimicrobial skin products (eg. hand santizer & antimicrobial soaps*), and house cleaning products. *Click on links to watch videos discussing some risks.
  • Avoid unnecessary use of pharmaceutical drugs, especially antibiotics (unless necessary and directed by physician).
  • Stop smoking
Join us Monday November 9th!
Next Monday at 6pm, Principled Chiropractic is hosting a FREE workshop all about how you can add probiotic rich foods into your diet. This is something that may be completely missing from your current diet.  If you want to be part of this class, you must call us to RSVP. We have limited space and already have had a huge response with many people already committed to attend. Sample will be provided as well as a culture starter (scoby) for making kombucha tea. Call us at 561-791-2225 to RSVP.

Author Info

Andrew Biggs, D.C.

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