IBS: What it is and isn’t

60 Million Americans suffer from irritable bowel syndrome, or IBS.  Are you one of them?  Do you know what IBS is?  Let’s start with what IBS is not.  IBS is not technically a medical condition.   It does not have a single root cause, and therefore, has no single cure.  What is IBS?  It is generally defined as a cluster of symptoms with no identifiable origin.   It’s a catchall that doctor’s typically apply to a particular group of symptoms.  IBS is a diagnosis given when all possible medical conditions are ruled out first.  I realize this is not very comforting, so let’s get a better understanding of IBS through a look at how the brain and digestive system communicate.


As I said, IBS is marked by a cluster of symptoms.  Some of these are gastrointestinal in nature, others don’t seem to have any connection to the gut.  Here is a list of common symptoms seen in IBS patients:

Change in stool compositionHeadaches
Chronic constipation or diarrheaFatigue
Abdominal cramping, especially after mealsInsomnia
Excessive gas or bloatingMuscle pain
Severe stomach pain
Mucus in the stool

Now, don’t go self-diagnosing IBS just because you experienced these symptoms after a huge holiday meal, or a short-period of time.  It’s normal for individuals not living with IBS to experience these symptoms on occasion.  Actual IBS is chronic, with symptoms occurring consistently for three to six months or more.

The Gut Brain Connection

IBS is caused by any combination of things (stress, lifestyle, diet imbalances) that can disrupt the nervous system in the gut.  Possible root causes of IBS include, but are not limited to SIBO, food intolerances, leaky gut, parasites, yeast overgrowth, zinc or magnesium deficiency, and heavy metal toxicity.  This list doesn’t tell the whole story though.  Nor does it help get to the myriad of possible causes that are not physiological in nature.  IBS is caused by any combination of things that affect the gut’s own nervous system, its production of digestive enzymes and the muscles involved in moving food through the gastrointestinal system.

I’m sure at some point in school you learned about the central nervous system and that it was comprised of the brain and spinal cord.  The central nervous system is comprised of the voluntary nervous system and the autonomic nervous system.  The autonomic nervous system is further broken down into the sympathetic and parasympathetic nervous system.  The sympathetic nervous system is responsible for the changes in our body during the fight or flight response, or stress.  The sympathetic nervous system is the system that controls rest and recovery and is the system of the two that is operating during digestion.  Remember, we talked about how you cannot digest your food properly if you are stuck in fight or flight because the sympathetic nervous is activated?  What you may not have learned, unless you took an advanced course in biology or anatomy and physiology, is that the stomach has its own nervous system called the enteric nervous system.  It’s actually part of the autonomic nervous system.

The nervous system of the gut actually has more neurons (nerve cells) than the brain and spinal cord combined.  All neurons, whether in the gut, brain or spinal cord communicate chemically via neurotransmitters:  chemical substances passed from one neuron to another for the purpose of activating or inhibiting some action in the body.  Many of these neurotransmitters are created by the bacteria in the gut.  So it’s actually the bacteria communicating in large part to our brains.  We’ve talked a lot about dysbiosis in the gut and how our microbiome is connected to dysbiosis.  If we have an imbalance in our gut bacteria, and these guys are creating the neurotransmitters that are used to talk to the rest of the body, is it becoming clearer just how impactful your gut microbiome is on your overall health?

IBS is classified as a problem with the gut-brain axis; the bidirectional communication between the brain and the gut.  The problem in IBS lies in the autonomic nervous system as a communication breakdown between the gut and the brain.

The connection between the gut and the brain in IBS becomes apparent with symptoms like depression and autism, more commonly considered problems of the central nervous system.  The microbiota in our gut communicate back and forth with the brain by means of neurons, hormones and the blood.  Gut microbiota may impact our reactivity to stress; the gut affecting the brain.  And the brain can affect the gut by interfering with digestion.  Let’s take motility issues as an example.  Motility is the movement of food through the stomach, small intestines and large intestines (colon).  The gut sends signals to promote motility by communicating through neurons in the gut that tell the stomach muscles (not your abdominal muscles, but the muscles inside the lower part of the stomach) to engage in peristalsis (movement), pushing food through the system.  The gut can do all of this without any communication to the brain.  However, when we’re stressed, the brain can impact peristalsis by sending messages to the stomach that slows down motility.  You can see here the potential link between stress and constipation.

Let’s look at depression, another symptom of IBS.  90% of serotonin in the body is located in the gut.  Serotonin is our happy hormone.  It is not surprising that gut health would affect serotonin levels and that depression and/or anxiety are one of the symptoms commonly present in IBS and other gut-related disorders.  Serotonin also plays a role in sleep, mood, appetite and pain sensitivity.  Why is all this important to our conversation?

The number of interactions being found between the gut and brain are growing.  The gut as a second brain in our body breaks open an area of study and knowledge that can help us understand the nature of symptoms that lead to no diagnosis of any physiological dysfunction anywhere in the body.  You know, when you have test after test performed and they all come back clean?

Addressing IBS

Because there is no root cause, or single cause of IBS, there is no quick fix.  And with the diversity of interactions being uncovered through study of the gut-brain axis, it’s hard to say if this is a good thing, making things easier to resolve, or a bad thing, making them more difficult.  Meaning, will it bring a greater understanding of IBS, or merely create more complicated relationships that need to be unraveled?  One example is stress.  Consider the impact of high levels of stress on the gut microbiome.  Stress compromises the immune system.  When the immune system is compromised we tend to get sick more often and may be prescribed antibiotics for some of these illnesses.  The antibiotics impact the microbiome further by killing off a lot of good bacteria along with the bad.  This becomes a vicious cycle when the microbiome is not re-established, and IBS symptoms can emerge with smaller and smaller triggers.  You end up with oversensitivity that wreaks havoc on the gut more frequently, or chronically.

Because the things that trigger IBS are different for each individual, addressing IBS long-term will be different for each individual.  For now, overcoming IBS means looking for things that aggravate the gut and subsequently healing the gut.  After all, if all disease begins in the gut, it’s a good place to start.

If you suspect that you suffer from IBS, you should talk to your doctor about testing and then considering a low FODMAP diet.  A low FODMAP diet focuses on eliminating foods that stress the gut, or that the gut is having trouble breaking down.  These could be fruits and vegetables high in fructose, dairy products, fiber, legumes, wheat and other grains, caffeine, alcohol, and other pro-inflammatory foods.  They generally fall in the category of foods not easily broken down eventually end up fermenting in the large intestines where most of IBS symptoms develop.  A properly supplemented, low FODMAP diet is not something anyone would take on willingly unless it is determined to be a solid route to quelling IBS symptoms.  This diet is not intended to be permanent (usually six weeks max) and is really too difficult to stay on long-term.  Once you determine what is driving IBS and address the causes, you will focus on adding these foods back into your diet.  You would then only revert back to a low FODMAP diet during flare-ups.

The key is to get to what is causing the problem.  The low FODMAP diet does not fix the problem, it merely addresses the systems.  Think of a low FODMAP diet as one that doesn’t require much work from the gut to digest food.  This is not good long-term as many of the foods excluded from the diet are important to a healthy diet, like fiber.  Furthermore, it does not address the issue.  Following a low FODMAP diet is no different than taking a drug to alleviate symptoms.  If you don’t get to the cause, you will never address the real problem(s).  In the meantime, the rest of the body is still suffering on other levels from whatever is causing IBS.  Lifestyle changes are going to provide more long-term, and doable, success in addressing IBS.

I hope this has provided you greater insight, not only into IBS, but also into the huge impact the gut and the microbiome have on overall wellness.  Tune in next week as we look at stress and how it impacts the gut and digestion.

Yours in Wellness,


Previous Post:  Autoimmune and Autoinflammatory Disorders

Next Post:  The Importance of HOW You Eat

Leave a Reply