Gut Brain Immunity
Is Your Gut Friend or Foe?
Written by Dr. Natalie Rahr, ND for the Gastrointestinal Society
Reprinted by permission from the Gastrointestinal Society.
Originally published on page 18 of the Inside Tract® newsletter, Issue 193, 2015.
“All disease begins in the gut”
Hippocrates made this statement more than 2,000 years ago. Since then, much has changed in medicine. However, this theory remains of great interest in the medical community, especially when considering the terrain of the individual, how robust their immune system may or may not be, and determining ways to treat our modern day chronic illnesses.
We live in an age when having a diagnosis of some kind is almost as common as having a job. We hear the terms IBS, IBD, autoimmune disease, hormone imbalance, arthritis, allergies, migraines, MS, asthma, neurodegenerative disease, eczema, depression, obesity, and so on.
Having a definitive diagnosis can certainly be beneficial for us to have an understanding of what is going on in the body and how it might be causing symptoms, but none of these diagnoses actually tell us why.
What if understanding the gut is the key to understanding why disease occurs? What if Hippocrates was right? This would mean that for almost all diseases and diagnoses out there, the root cause is in the gut, that what is going on in the gut has ripple effects in the body and that the gut is always a factor in determining disease or health, either partially or completely.
In my practice as a naturopathic doctor, I see a wide variety of health conditions, and more often than not, when we treat the gut, along with making sure all other ‘pillars of health’ are in place, such as sleep, nutrition, exercise, stress management, etc., the symptoms of disease diminish and often go away altogether.
How can that be? What does your gut have to do with your headache or your skin rash or your joint pain?
The Importance of Having Guts: A Genetic Potluck
Not only is the gut our second brain (and some would argue it to be our first), due to the multitude of neurons in the enteric nervous system and the amount of neurotransmitter production that takes place in the gut, it contains the majority of the microbial DNA that dictates our complex functioning as humans. That delicate balance of the good and bad bacteria in the gut, also known as the microbiome, plays a large role in the health of the whole person. We are even more aware of this since scientists mapped out the human genome early this century. Researchers were amazed at the unexpectedly small size of the human genome, which is roughly equivalent to that of a dragonfly. As it turns out, later research has shown that only 1 in 10 cells in the body are human. The other 9 (or 90%) are microbial. This 90% contains the DNA from the microbes that live in and on the body and provides essential functions for the human as a whole.
The Good, the Bad, and the Commensal
When talking about the balance of good (beneficial) and bad (pathogenic) bacteria in the gut flora, there is one more category of microbe to be aware of when thinking about the gut’s influence on the rest of the body and, prior to that, the influence of the environment on the gut. Commensal bacteria are those bacteria that can go either way; they are neither fully beneficial nor are they pathogenic, they act neutrally. This is where much of our own lifestyle influences come into play in the development of health or disease. If we eat a clean and healthy diet, manage stress well, get lots of sleep, fresh air and activity, these commensal bacteria are inclined to go over to the good side. If the opposite is true, then they can turn bad. The stronger one side is over the other, the more influence it has over these commensal microbes, just like a game of red-rover, the side with the strongest hold grows and wins.
To add complexity, we require all these types of microbes in the right amounts to benefit the body. The beneficial bacteria provide the body with nutrients and help remove waste. The pathogenic bacteria, in a balanced amount, train the immune system. When the pathogenic bacteria overtake and overwhelm the beneficial bacteria things can go awry in the body. Dysbiosis, or an imbalance in the microbiome, has effects on the gut such as increasing permeability and integrity of the gut lining, leaving the body more susceptible to autoimmunity and inflammatory disorders.
In short, our microbiome influences our health, and we influence the health of our microbiome.1
From the Gut to Disease
So if something is going wrong or is out of balance in the gastrointestinal tract, how does this translate to symptoms in areas of the body that, seemingly, have nothing to do with the gut?
The common analogy I use to illustrate for patients how some health care professionals believe gut health affects health of the entire body is that of a clogged kitchen sink. Imagine the things that end up in your kitchen sink every day, and imagine it all building up. That drain eventually clogs.
In the body, the main drain is analogous to the gut and your liver, your main detox pathways and means for waste elimination. Should their function become impaired to some degree due to being overwhelmed with the quantity or quality of what it is trying to eliminate, the rate at which your body (the sink) can eliminate potentially toxic by-products of metabolism slows.
Now imagine this continues for years. The level in that clogged kitchen sink begins to rise, eventually reaching the point of spilling over. Each individual exhibits unique symptoms when this spillover occurs. Early research suggests that these symptoms of spillover can be anywhere from fatigue, mood disorders, developmental disorders, skin rashes, allergies, asthma, to serious complications such as multiple sclerosis (MS) or other severe immune dysregulation or autoimmunity.
This seems to depend on the degree of impairment in function of the drain, the quality of what is accumulating in the kitchen sink (what we put in and what we are exposed to, whether it be the food we eat, the medications we take, the environmental toxins we take in, or other factors), and what tools we use to assist the drain with the elimination of waste and toxicity.
Essentially, the integrity of the gut is analogous to the integrity of a drain, responsible for allowing everything to flow through the body with ease.
The Gut, the Brain, and the Gut-Brain Axis
Do you ever get a gut feeling: something you know in your gut even before your brain can explain it? What about butterflies in your stomach when you’re anticipating something? Perhaps when you experience stress you feel it in your gut without necessarily thinking about it.
Research continues to show us the strong links between the brain and the gut. For example, some small studies show that a leaky gut could imply a leaky brain. ‘Leakiness’, or hyperpermeability, in the gut, in part due to an imbalance in the flora, creates a playground for inflammation that cascades systemically throughout the body. Inflammation occurring in the gut might lead to inflammatory processes in the brain. By the same token, what is occurring in the brain could affect the gut via the vagus nerve, altering motility, function, and secretions.
In neurodegenerative diseases such as MS, one study identified hyperpermeability in the blood-brain barrier (BBB), as well as in the tight junctions of the intestinal wall.3 Another study linked this similar leakiness to the autoimmune response in the myelin sheath, or protective fatty layer wrapped around the nerves, causing a breakdown in function.
The gut can also exhibit localized symptoms such as gas, bloating, diarrhea, and constipation among others, which can be transient and benign, or involve disease processes that penetrate deeper into the gut wall. “The clearest correlation between dysbiosis and disease has been found with inflammatory bowel diseases (IBD)…”,7 including Crohn’s disease and ulcerative colitis, in which strictures and obstructions are among some of the serious complications.
Effects on the gut-brain axis can cause changes to gut flora in conditions such as irritable bowel syndrome (IBS). Recent research also links depression and anxiety to an inflammatory reaction in the gut.8,
Individuals with obsessive-compulsive disorder (OCD), pediatric acute-onset neuropsychiatric disorder associated with streptococcal infections (PANDAS), and neurodevelopmental disorders such as autism and attention deficit hyperactive disorder (ADHD) have all shown alterations in gut flora.1,
Understanding the gut’s influence on the brain as well as the brain’s influence on the gut is a fascinating step toward treating the person as a whole, and not exclusively by symptoms.
The Gut, Allergies, and Atopic Disease
While an obvious allergic reaction or anaphylaxis clearly allows you to identify its cause, the increasingly more common delayed food sensitivities can cause an array of symptoms anywhere from local abdominal pain and bloating to migraines, body pain, skin issues like rashes or acne, and so on. These symptoms may not show up for hours or even days, making it tricky to figure out what is causing the reaction.
In practice it is quite common to have patients test positive for a few-to-many food allergens, when testing for serum immunoglobulins, only to have them eliminate those foods and find that 3 to 6 months later, they now test sensitive to foods they did not initially test sensitive to. This leads some practitioners to suspect that intestinal hyperpermeability (leaky gut) is a factor and may play a role in developing food sensitivities.
Dysbiosis might also be a contributing factor. In infants, the development of food allergies and sensitivities could be related to an overabundance of certain types of pathogenic bacteria, such as Clostridiae along with fewer good bacteria.
One study found that in atopic disease such as atopic dermatitis (eczema), the skin microbiome, which the balance of the gut microbiome indirectly alters, is very different from that of healthy skin. The study found the same to be true for psoriasis.
Other symptoms of atopic disease, such as asthma, also relate to gut health. Functional and structural abnormalities, specifically in asthma, relate to persisting inflammation in the lungs and link to altered gut flora. This predisposes an immune response to occur when allergens are present, causing sensitization to these allergens and subsequent symptoms of asthma.
The Gut and Joint Pain
Dysbiosis and intestinal hyperpermeability might play a role in joint inflammation. When an antigen, such as an offending food or toxin enters the blood stream from the gut, the immune system kicks in. An antibody, plus its target antigen, bind together to form a ‘complex’. This complex circulates, causing other cascades of inflammation as it goes, finally depositing in places like the joints. The joints are particularly susceptible because there is low blood circulation to flush the inflammatory complexes out.
A toxemic theory, proposed at the turn of the 20th century, alluded to a build-up of this toxicity in the body from infectious agents ultimately promoting joint inflammation. In a recent study, researchers have correlated an overgrowth of Prevotella copri to an increased susceptibility to rheumatoid arthritis.
The Gut and Obesity
Alterations in the gut flora may play a part in the development of obesity. (See the Inside Tract® issue 192.) Reduced bacterial diversity is common in obese individuals, which researchers believe may be interfering with metabolic pathways, since the gut harbours many microbes responsible for regulating metabolism and extracting energy from otherwise indigestible elements of the diet. One study reviewing the microbiome diversity of obese and lean mice suggests that microbes play a role in the efficiency of calorie use and calorie storage in the body.
The Gut and the Immune System
Have you ever been the only person in your household who doesn’t get sick, or are you the first to get sick?
The gut is our main route of contact with the external world; 70% of the immune system is located in the gut. This is mediated through the gut-associated lymphoid tissue (GALT), which is responsible for orienting immune response to contents in the gut and for the production of 80% or our main first immune response, that of Immunoglobulin A (IgA) in the mucous layer.
In a study on the effect of the gut microbiome on the flu virus infection, the immune modulating effects stretch far beyond the gut to the respiratory mucosa, acting protectively.
Increasingly, some health care professionals recognize that disruptions in the commensal microflora may lead to immune dysfunction and autoimmunity.
So Is Your Gut Friend or Foe?
It’s your friend!
If the gut is the root of all disease, as Hippocrates suggested, then, it could also be the root of all wellness.
In other words, if it is true that disease does begin, or has something to do with some amount of disruption, in the gut environment, then this could mean that the root of all health also lies in the gut and in healing the diversity of this environment.
What to Do?
Thus begins your journey of healing the gut.
First, when looking to protect and nourish a healthy gut, think basics: think slow food, single ingredient, whole food, colourful food, and think fresh, unprocessed, and seasonal food, live and fermented foods, and nutrient-dense foods.
As for what to minimize or avoid as much as you can, think medications such as antibiotics, oral birth control, NSAIDs, caffeine, alcohol, processed and genetically modified foods, processed sugar, foods you are sensitive or allergic to, food dyes, packaged, and pasteurized foods.
There is also much talk around seeding the microbiome of a baby’s gut before, during, and after birth. This promotes the development of a healthy immune system, through prenatal health care and preparation of the mother and father, natural vaginal birth, and breastfeeding, along with ongoing exposures to the environment through childhood to train the immune system and increase the diversity of the child’s microbiome.
These basic things are a great start to help the gut move to a state of greater health, and therefore help the whole person establish or maintain health.
Keep in mind that once a disease state is already in process, testing and stronger treatments are required. These might include high dose nutrient supplementation, medications, or natural methods of assisting the body with eliminating accumulated toxins. Naturopathic doctors and functional medicine doctors are the experts in holistic care to help get you on track, deal with the root cause of illness, and address your individual needs. We work closely with your conventional medicine team to ensure a smooth, effective treatment plan.
Dr. Natalie Rahr, ND practices in Vancouver, BC. Contact her at or 778-858-7247.
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