Nerves: The Brain-Gut Connection


Do you ever wonder why you get “butterflies in your stomach” when you’re nervous?  How about “stress eating” or “comfort eating”?  Have you thought about where the term “anal retentive” comes from, and if it really does apply to uptight people?  Is there truth behind these metaphors?

Much research has been done about the effect of foods and food additives on brain function.  Think Tryptophan.  This amino acid in turkey has a sedative effect and makes you tired after a Thanksgiving dinner.  MSG is a neurotoxin frequently used in foods as a flavour-enhancer.  It can cause headaches, nausea, mood swings, dizziness, arrhythmia, and partial paralysis in sensitive people.  Essential fatty acids, as in cod liver oil, and micronutrients, such as folate, are necessary components for brain development.  But what about the other half of the equation?  What effect, if any, does the brain have on the digestive system?

The digestive system, because it’s not under our conscious control, is thought to have a separate control system of its own.  It does, in fact, have its own “brain”, called the “enteric nervous system”, which works together with the brain and spinal nerves.  This complex controls all the different organs of the digestive system to work in harmony, every step of the way.

The process of digestion is much more complicated than most people can imagine.  First, there are signals to tell you when and what to eat or drink (hunger, thirst, cravings).  Then, your body needs to identify the foods and produce the right types of enzymes and acids to break them down.  You’ll need to secrete the right amount, at the right time, and in the proper concentration to be effective.  Then there’s the physical moving of the food along, in a coordinated fashion.  In the mouth, you’ll start with biting and chewing the food with actions of the jaw, plus moving the food with the tongue. Then, you’ll need to swallow to bring the food down the esophagus towards the stomach and not down the nasopharynx to your lungs.  (If it does go down the wrong path, you’ll need to trigger the cough response or else hope someone close knows how to do the Heimlich Manoeuvre).  Is there enough water and mucous to help the food go down?  The valve between the esophagus and stomach will need to open in time, and close promptly to prevent backwash of stomach acids into the esophagus, otherwise you’ll feel nasty heartburn, also known as “acid reflux”.   The stomach has lots of work to do.  There’s the preparation of stomach acids, churning of the food around, and signalling back to the brain about whether you’re full or still hungry.  This is just the beginning.  There are many more processes to come, involving other organs such as the liver, pancreas, gallbladder, small intestines, large intestines, appendix, and rectum before we get to the anus and excretion of the non-digestible food matter.

The digestive system works automatically to some degree, but is also sensitive to the state of the rest of the body.  When the body and mind are relaxed, “housekeeping” organs and systems go about and maintain, grow, heal and repair the body.  This includes not only the digestive system, but also the cardiovascular, reproductive, and immune, but also bone growth, muscle development, etc.  In times of stress (fear, danger, crisis, toxicity, grief, injury, challenges), the sympathetic nervous system takes over and up-regulates functions for increasing alertness, reflexes, strength, speed, and endurance, while suppressing housekeeping functions that can wait until you are out of danger.  If the stress is chronic or severe enough, the digestive (or other) systems may malfunction or shut down, and create a disease state.

The parasympathetic nervous system connects the digestive system to brain via cranial nerves originating in the brain and upper neck, and via nerves from the sacrum at the base of the spine.  The upper set control all organ and gland functions in the head, neck, thorax, and abdomen as far down as the first third of the large intestine.  The largest and longest parasympathetic cranial nerve is the vagus nerve.  The sacral parasympathetic nerves control the lower two-thirds of the large intestines, plus pelvic organs and controls elimination (urination, defecation, ejaculation, menstruation, birth).  Nerves of the sympathetic nervous system, however, come from the middle levels of the spine (T1 to L2).  The upper nerves go up the neck to affect the head, middle nerves to the thoracic and abdominal organs, and lower nerves to the lower abdominal and pelvic organs.

The nerves of the parasympathetic or sympathetic nervous systems can get injured or compromised, either by injury to the spine at the levels they exit, or by over-stimulation.  Either way, the spinal joints can become misaligned or “subluxated”.   Subluxations in the upper neck can have severe impact on the cranial nerves, especially the vagus nerve, and can cause nausea, changes to stomach acidity, ineffective nutrient absorption, difficulty swallowing, sleep apnea, cardiac arrhythmia, dizziness, eye twitches, ringing in the ear, and blood sugar imbalance.  This can be the result of injuries to the head and neck such as whiplash, concussion, repetitive stress of forward head carriage (“text neck”), birth trauma, and sports injuries.  The sacral parasympathetic nerves can be compromised by falls onto the buttocks, horseback riding, excessively sedentary lifestyle, breech position in-utero, pregnancy and birthing.  When sacral nerves misfire, issues such as bedwetting, incontinence, constipation, diarrhea, endometriosis, infertility, sexual dysfunction, repeat urinary tract infections, and hemorrhoids are possible.  Mental, emotional and chemical stresses aggravate the sympathetic nerves.  These areas of the spine can also subluxate from poor posture (slouching), chest tightness, shallow breathing, prolonged respiratory infections, carrying heavy backpacks, and ill-fitting bras.

Medications and diet modification are common treatment protocols when the digestive system is not functioning properly or causing discomfort.  Medications, whether over-the-counter or prescription, are designed to relieve symptoms, often regardless of the cause.  Diet modification, especially under the guidance of a holistic nutritionist, seeks to remove harmful foodstuff and foods that a person cannot handle at that time, and offer tasty, nutritious food choices to fulfill your body’s needs.  Chiropractic care serves to restore proper nerve flow so that the body can heal itself and function properly once more.  When the digestive system is functioning optimally, it won’t be as sensitive to foods such as tomatoes, gluten, and dairy; it won’t be as prone to food poisoning, acid reflux, hyper/hypoglycemia; and bowel movements will be more regular.

When your lifestyle is already on the right path, chiropractic care increases the effectiveness of good habits so that you can better enjoy your day-to-day life.  If you need help getting onto the right path, chiropractic is a good first step and we can guide you on what you can do to help yourself be healthier and happier.  You deserve better health and more joy in your life.  Ask us how we can help you on your journey!  Click here to download a free Baseline Health Questionnaire and we can get the conversation started.  This could change your life!