We have all had temporary stomach upset and problems going to the bathroom, but for individuals suffering with irritable bowel syndrome (IBS) the discomfort and inconvenience can be disabling. 

Not to be confused with inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn’s disease; IBS is a common digestive tract disorder that affects the colon (large intestine) but does not cause damage to it.

What Causes IBS? 

  • Muscle contractions in the intestine. The walls of the intestines are lined with layers of muscle that contract as they move food through your digestive tract. Contractions that are stronger and last longer than normal can cause gas, bloating and diarrhea. Weak intestinal contractions can slow food passage and lead to hard, dry stools.
  • Nervous system. Abnormalities in the nerves in your digestive system may cause you to experience greater than normal discomfort when your abdomen stretches from gas or stool. Poorly coordinated signals between the brain and the intestines can cause your body to overreact to changes that normally occur in the digestive process, resulting in pain, diarrhea, or constipation.
  • Infection. IBS can develop after a severe bout of diarrhea (gastroenteritis) caused by bacteria or a virus. IBS might also be associated with a surplus of bacteria in the intestines (bacterial overgrowth).
  • Stress. People exposed to stressful events tend to have more symptoms of IBS.
  • Changes in gut microbes. Examples include changes in bacteria, fungi, and viruses, which normally reside in the intestines and play a key role in health. Research indicates that the microbes in people with IBS might differ from those in healthy people.


A “functional” gastrointestinal disorder and “syndrome.”

Functional gastrointestinal disorders are characterized by chronic or recurring symptoms as a result of abnormal functioning of the GI (gastrointestinal) tract. This means normal function of the gut has been altered in some way. 

Syndrome means “running together.” IBS is a group of symptoms existing together. In the case of IBS, there are common symptoms (see below) but the cause of these symptoms or how they are related is not clearly understood.

To summarize; IBS is a functional disorder (the gut is not working the way it should) and it is a syndrome (nobody knows exactly what causes it).The good news is that functional medicine doctors specializes in functional disorders   and just because a single cause for IBS has not be identified, it does not mean it cannot be successfully treated.

“IBS is a condition, in which the gut is hypersensitive and hyper-reactive to stimuli… This hyper-reactivity could be caused by increased mucosal permeability, increased numbers and/or responses of mast cells, and enhancement of nerve reflexes of the vagus nerve…”


This means there can be gut permeability issues such as a leaky gut, changes in mast cells which would affect histamine levels in the gut and brain  and altered function of the vagus nerve which is a large nerve that run from your brain to your gut. 

Nervous system

“The altered bowel function, abdominal pain, and sensitivity symptoms indicative of IBS result from what appears to be a disturbance in the interaction among the gut, the brain, and the Autonomic Nervous System – which includes the Parasympathetic (vagus nerve) Sympathetic, and the Enteric Nervous System – or ENS – now recognized as the “brain below.” The ENS is also called the “second brain” of your body. 



“People with IBS often experience a strong urge to use the bathroom and may avoid going to places without easy access to one. This means that many everyday locations (malls, parks, places of worship, movie theaters, classrooms, offices) feel risky, and people might start to limit their activities as a result. 

People with IBS also start to fear and avoid many foods believed to trigger IBS attacks, often leading to loss of pleasure in eating as well as reduced opportunities to socialize.”

Many individuals with IBS suffer from anxiety that may or may not be linked to the stressors listed above. 



Scientific evidence strongly suggests that serotonin is one of the most important signaling molecules (nerve chemical) involved in gut function – and that alterations in serotonin signaling may contribute to IBS symptoms. Ninety-five percent of the serotonin found in the body resides in the gut. Altered serotonin the gut can contribute to IBS and altered serotonin balance in the brain can lead to anxiety, problems with sleep or depression. 


“Most research has linked estrogen and progesterone with IBS. But scientists have also found that male sex hormones, like testosterone, may protect against the condition. This may be partly why men are less likely to get the disorder.”



“Patients with IBS frequently experience worsening of their symptoms after eating. Moreover, a vast majority of IBS patients feel that distinct foods play pivotal role in triggering their symptoms. In a recent study, 58% of patients with IBS experienced GI symptoms from histamine-releasing food items such as milk, aged cheese, wine or beer.” 


Histamine is a not only a chemical of the immune system, but it also acts like a neurotransmitter and can significantly influence how the digestive system and the brain function. 

Food allergies, Food intolerance and Low FODMAP

FODMAP = Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols…carbohydrates 

“Carbohydrate digestion and absorption is surprisingly complex. In order for carbohydrates to be properly digested, the wall (“brush border”) of your small intestine has to produce specific enzymes. If you do not optimally produce the enzymes or if the brush border of your small intestine is inflamed, carbohydrate digestion will be compromised.”


The most popular diet plan for IBS would be the low FODMAP diet. The idea behind this is that the small intestine is not making sufficient enzymes to breakdown certain carbohydrates and this leads to the symptoms of IBS. 

I do not generally recommend this diet for my patients, not because I do not believe it has merit, but simply because it does not identify what caused the small intestine to become dysfunctional and lose the ability to breakdown these carbohydrates. Many things alter the health and function of the small intestine…food allergies, food sensitivities, stress, cortisol, bacteria, yeast, parasites, viruses, toxins, hormonal imbalances…etc. 

Leaky Gut 

“Inside our bellies, we have an extensive intestinal lining covering more than 4,000 square feet of surface area. When working properly, it forms a tight barrier that controls what gets absorbed into the bloodstream. An unhealthy gut lining may have large cracks or holes, allowing partially digested food, toxins, and bugs to penetrate the tissues beneath it. This may trigger inflammation and changes in the gut flora (gut microorganisms) that could lead to problems within the digestive tract and beyond.” A leaky gut can cause IBS as well as many other health problems. 


SIBO= Small Intestinal Bacterial Overgrowth 

What is SIBO?

“Small intestinal bacterial overgrowth (SIBO) is a serious condition affecting the small intestine. It occurs when bacteria that normally grow in other parts of the gut start growing in the small intestine. That causes pain, gas, bloating and diarrhea (symptoms similar if not identical to IBS)

 It can also lead to malnutrition as the bacteria start to use up the body’s nutrients.


How we can help

As you can see from the information above, there is not a single root cause for IBS.  I’m guessing there will never be single cause identified, simply because many sufferers have been successfully treated using a variety of approaches. 

It is important to understand that IBS can have multiple causes. It can be caused by diet, a leaky gut, hormonal imbalances, nerve chemical imbalances, imbalances of digestive enzymes or stomach acid or nutrient deficiencies, etc. 

There is only one type of doctor that is familiar with all of these possible causes and that would be a functional medicine doctor. 

In our office we look for the underlying, root causes of IBS. We are able to accomplish this by consulting with you and collecting information through unique testing procedures that lead us to the root cause of your IBS.

You are not alone, we are here to help. You want to feel like yourself again. You want your life back. Let’s see if we can get you there