4 quadrants of gi health


Before we dive into the 4 Quadrants of GI Health, it is important to be on the same page with what we mean by GI tract and what a normal functioning GI tract is like.  The GI tract is short for Gastrointestinal Tract. This is essentially a closed system from the mouth to the anus that changes food into fuel for the body and protects our bodies internal environment from the outside insults of toxins and infections. The GI Tract includes the upper, middle and lower portions.

The upper GI tract includes the mouth, esophagus and stomach. Problems that can arise in the  upper GI tract include:

  • Oral bacteria causing not only oral disease but leads to inflammation in the entire body
  • Acid reflux/ GERD usually caused by low stomach acid, food sensitivities, and imbalances of gut bacteria in the colon.  Approximately 60% of the US population suffers from reflux. This condition occurs when stomach acid exits the stomach via the esophageal sphincter and causes pain, irritation, and even damage in the esophagus
  • Hypochlorhydria– the condition of low stomach acid which creates problems in the entire GI tract including GERD, impaired immune system function, and contributes to food sensitivities, and is usually the cause of GERD or Acid Reflux
  • Low digestive enzyme production in the stomach is extremely common and prevents food from breaking down all the way. Stomach pain can have a variety of causes, but is often related to the quantity and quality of enzymes and bacteria through the whole GI tract. Both enzymes and bacteria have a major affect inflammation and leaky gut.

The middle GI tract includes the small intestines, liver and gallbladder. Many people don’t realize how important each of these organs are to the body. Over 600,000 gallbladders are removed (a procedure called a cholecystectomy) in the US each year and no one is talking about the number of people whose health worsened after the gallbladder removal. Rather many treat the gallbladder like a bonus organ that can be tossed out if it acts up.  We are absolutely certain there are no organs in our body that we do not need. If there were, why would it be there? The small intestine is where enzymes and bile from the liver (via the gallbladder) continue digestion by breaking down fat, protein and carbohydrates into nutrients small enough to be absorbed into the blood. These nutrients go through the liver and are distributed to the rest of the body. Problems with the middle GI tract include:

  • Small intestinal bacterial overgrowth (aka SIBO). This increasingly common condition is the cause of many people’s stomach pain, nausea, and problematic stools. It is a condition where bacteria that should be in the large intestines is actually growing in the small intestine where it shouldn’t be, therefore causes a vast array of problems.
  • Unnecessary gallbladder removal or cholecystectomy which impairs the rest of digestion and can create more problems than it solves, from detox issues, poor fat metabolism, increased risk of biliary tree obstruction, dysbiosis and much more.
  • The liver is a major player in detoxification. In cases of leaky gutautoimmune disease,fatty liver disease, cancer and many more conditions, the liver can be so overworked by stress, toxins, and poor diet, that it simply can’t keep up anymore causing health to suffer.

The lower GI tract is where digestion wraps up in the large intestine including the colon and rectum. Fiber and indigestible starches not broken down by enzymes pass to the large intestine where bacteria break them down for energy. The bacteria and leftover fiber become feces (aka poop). Problems in the lower GI tract include:

  • IBD or irritable bowel disease which includes Ulcerative Colitis and Crohn’s disease. Problems in the lower GI tract are detected by symptoms the diseases above can cause, but these disease commence because of issues which have been brewing for a long time further up in the GI tract long before symptoms occur.  Another contributing factor to IBD disease’s setting in is due to the use of many medications incorrectly Rx and surgeries performed when they should not have been.  
  • IBS or irritable bowel syndrome is less serious than IBD, but as problematic in terms of discomfort and signs that there are issues in other areas of the GI tract that need to be addressed.


Many people operate under the assumption that common symptoms are normal GI function.  It is critically important to understand, just because conditions like nausea, bloating, diarrhea, cramping, or heartburn (reflux) happen in a lot of people, making them common, does not mean this is how a healthy GI tract should work or that this normal for anyone. In all actuality, most people suffer from some sort of abnormal GI function and don’t even know it is abnormal. Normal digestion should go unnoticed. Frankly the only thing you should notice after eating a snack or meal is the sense of mild satiation or satisfaction.

Normal digestion should result in 1-2 medium brown, soft, formed stools daily. There should not be pieces of food in your stool. Your GI tract was made to eliminate daily, but not excessively. If you need medication or any “aid” in preventing constipation, that is not normal. If you have more than 2 stools daily, that is not normal. The Majority of people today live with one or more of the above symptoms for years, if not their whole life.  They assume that’s what should be happening or is normal for them. It is not.  A healthy GI tract is a relatively silent, but powerful force in your body that aids in detoxifying and fueling your entire body.

The GI Tract Affects The Whole Body

Although it is helpful to understand each area of the GI tract separately, each area affects the whole body. There are many diseases that develop as a result of an unhealthy GI tract that are not contained only in the GI tract. Actually, almost all diseases can be traced back to an issue in the GI tract. Here are some examples:

The health of the gut is influenced by a variety of factors related to: diet, environmental factors, body burden of toxicity, as well as our genetic predispositions. This is why understanding the functionality of the GI tract in terms of 4 Quadrants is a more appropriate way of understanding GI health than simply looking at diseases in different areas of the GI tract.



The most obvious function of the GI tract is to digest food, absorb the nutrients and protect the internal environment from outside invaders and toxins, but when it is compromised, it severely impacts health of the entire system. Poor digestion of food as a result from inflammation, poor enzyme production, imbalances of bacteria, and poor food choices lead to nutrient malabsorption and the body no longer gets the nutrients it needs in the amounts needed for optimal health. A person can eat the highest quality foods and take the highest quality supplements, but if the gut cannot absorb the nutrients provided, then the body still suffers. Proton Pump Inhibitors (PPIs)/ Histamine (H2) blocking medications and stress also slow down digestion and both actually decrease enzyme production in the body contributing to issues like malabsorption and reflux.

Ways to improve digestion and absorption include:

Quality Food Choices

  • Organic food as often as possible (see Clean 15 and Dirty Dozen lists from www.ewg.org)
  • grassfed/pastured/organic meats
  • Increase fruit and vegetable intake
  • Limit sugar intake
  • Use filtered water
  • Enjoy meals sitting at the table with friends and family
  • Chew food thoroughly before swallowing
  • Consume fermented foods

Reduce Stress Levels

  • Control inflammation
  • Maintain healthy blood sugar levels
  • Balance/address mental and emotional stressors
  • Get adequate and quality sleep
  • Have regular times of play and creativity
  • Set down the phone or get away from the computer!  It will be ok – we promise.  

Supplement Effectively (these are examples of common supplements for GI health, but supplementation should be done with a practitioner who can prescribe supplements based on your unique needs)

  • Supplements to improve Gastric (Stomach pH) to address hypochlorhydria like Betaine HCL and Pepsin
  • Digestive enzymes
  • Probiotic + Saccharomyces boulardii (if indicated)
  • Soluble and insoluble fiber


The liver is the body’s best detoxification resource. It works with the GI tract to remove toxins from food and the environment including cleaning and body care products. When the GI tract is compromised, additional burden is placed on the liver. It is important to have regular detoxification in your lifestyle like eating greens and putting fresh lemon or lemon essential oil in your water, but also times of more strategic detoxification to restore the body’s ability to eliminate toxins and take the pressure off the liver.

For this article we will discuss two phases of detoxification. Phase I is responsible for converting fat soluble toxins (most toxins are fat soluble) into intermediary metabolites. These metabolites are usually more harmful than the original toxin, but a necessary step in removal by the body. This is where Phase II takes over by quickly changing the metabolites into water-soluble compounds that can be eliminated through the stool and urine. If Phase I detoxification is not working well, toxins stay stored in your fat tissue contributing to hormone imbalances, weight gain, and skin issues, just to name a few. If Phase II is not working well, then highly reactive toxins are mobilized through the body which is just as problematic. Nutrients needed in Phase I include: B2, B3, B6, B12, Folate, Glutathione, Flavonoids.  Nutrients needed in Phase II include: Methionine, Cysteine, Magnesium, Glutathione, Vitamin B5, B12, Vitamin C, Glycine, Taurine, Glutamine, Folate, Choline

Ways To Improve Detoxification and Elimination Include:

Quality Food Choices:

  • Identify and eliminate food sensitivities
  • Avoid gluten, dairy and soy foods
  • Increase fruit and vegetable intake – especially cruciferous veggies
  • Limit sugar
  • Choose organic and seasonal produce and pastured, grassfed meats

Limit or Avoid Toxin Exposure

  • Environmental Toxins: pollution, solvents (paint, cleaning products) heavy metals, pesticides, herbicides, insecticides, radiation, inhalants
  • Lifestyle Toxins: inflammatory foods, cosmetics, nicotine, alcohol, caffeine, prescription drugs, over-the-counter drugs, artificial food additives, colorings and preservatives, refined foods and sugars.
  • Internal Toxins: bacterial, yeast, fungal overgrowth, undigested food, stress, unresolved trauma or abuse, unhappy relationships

Supplement Effectively

  • Acute detoxification program
  • High Quality Multivitamin – most supplements on the market are not of quality and have a lot of toxic excipients, binders, fillers and toxic raw material.  
  • Phytonutrients
  • Most importantly a synergistic nutritional program is critical


The term gut microbiome is a “hot topic” in the health world, and for good reason as it is the cornerstone of health. The microbiome is the collection of microorganisms that inhabit an environment, creating a unique ecosystem. The human microbiome consists of trillions bacteria, fungi and viruses and is directly influenced by food choices and toxins. It is an ever-changing environment that represents your health. Imbalances in this ecosystem is called dysbiosis and is a factor in countless chronic health conditions. Bacteria are the key players here by protecting against infections, improving digestion, making vitamins, and supporting the immune system.

Dysbiosis happens because of chronic stress, poor food choices, infections, toxins and antibiotics to name a few. This causes inflammation, intestinal permeability or leaky gut problems, food sensitivities, nutrient malabsorption, and irregular bowel movements. When these issues are not addressed, they become chronic conditions like obesity, depression/anxiety, autoimmune disease, IBD and IBS and allergies to name a few.

Ways to Improve Gut Microbiome:

Quality Food Choices:

  • See Quadrant 1 and 2

Limit Exposure to Antibiotics

  • Use filtered water to decrease exposure from water
  • Choose high quality meat to decrease exposure from food
  • Only use antibiotic medications when absolutely necessary- instead look for other ways of fighting problematic bacteria with essential oils, colloidal silver, certain herbs and pre and probiotics
  • Increase fermented food intake and probiotics

Supplement Effectively

  • Pre and Probiotics
  • L-glutamine, deglycyrrhized licorice, and other gut healing supplements
  • Immunoglobulins
  • Fermented foods


The GI tract is made up of a semi-permeable membrane or selective barrier that allows absorption of beneficial substances into the bloodstream and keeps out those that are harmful. This gut barrier (intestinal lining) is constantly exposed to foods, toxins, and chemicals from which it must defend itself. If food particles that are not broken down all the way due to poor digestion cross the barrier into the bloodstream, inflammation increases as the immune system attacks the large food molecules as a foreign invader since it is not a size that is recognizable as a “friend” by the immune system.  This process also breaks apart what are called tight junctions in the intestinal wall lining allowing more types of unhealthy particles to pass through such as medications and infections. This continues the vicious cycle of breaking down the gut lining causing more inflammation and over time, chronic disease including all types of autoimmune diseases. This breakdown of the gut lining is commonly referred to as leaky gut syndrome.

Ways to Improve Intestinal Permeability (Leaky Gut)

Quality Food Choices

  • See Quadrant 1-3
  • Eliminate food sensitivities based on quality lab testing or elimination diet
  • Focus on whole, unprocessed foods

Limit Exposure to Antibiotics

  • Use filtered water to decrease exposure from water
  • Choose high quality meat to decrease exposure from food
  • Only use antibiotic medications when absolutely necessary- instead look for other ways of fighting problematic bacteria with essential oils, colloidal silver, and probiotics
  • Increase fermented food intake and probiotics

Reduce Stress Levels

  • Balance mental and emotional stressors
  • Maintain healthy blood sugar levels
  • Improve sleep quality
  • Decrease inflammation

Supplement Effectively

  • Probiotics
  • L-glutamine, deglycyrrhized licorice, and other gut healing supplements
  • Immunoglobulins
  • Anti-inflammatory phytonutrients (curcumin, Quercetin, etc)
  • Digestive enzymes


There are many approaches to gut healing and it is worth noting that more is not always better. More probiotics, more herbals, more detoxification are NOT always the answer and can be too irritating for some. Working with a practitioner who can understand your story, determine the appropriate functional labs to see what is the driving force behind your GI issues, and supplement specifically for your body’s needs will save you time, money, and frustration in your healing journey.

Final Thoughts

The GI tract is a fascinating, complex collection of organs and systems that at the end of the day determines the quality of your health. There is no substitute for a healthy gut. While treatment for complex or persistent gut issues needs to be done with a qualified functional medicine practitioner, there are tried and true principles of gut health that work well for almost everyone.

To get started on improving your gut health choose real food as close to its original source as possible, choose organic foods whenever possible, clean with non-toxic products and choose body care products that are made without chemicals and toxins. In addition, balance life’s inevitable stress by quality rest, healthy relationships, and space for creativity and play. You are a whole person. Therefore, your emotions, dealing with past hurts and your ability to maintain hope for the future can affect your gut health as much as the quality of your probiotics, water source or food quality. Any steps you can take towards improving your food, quality of sleep,  and stress are always going to contribute to improved gut health and begin to build a good foundation from which to build. Your functional medicine practitioner at in2GREAT will help you to begin addressing each of the 4 Quadrants of GI Health in the way that is right for you.

Dr Corey Priest, DC - Functional medicine practitioner

About the author

Dr. Corey Priest has been practicing functional medicine since 2001. in2GREAT was founded in 2014 by Dr Priest after 13 years of experience with his other practices. Over his career, Dr. Priest has worked with and helped well over 10,000 patients under a functional medicine model.

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