Diarrhea, Urgent Stools and Bacterial Overgrowth Syndrome

Bacteria and Our Intestinal Tract

Our intestinal tract is home to billions of bacteria which are made up of 35,000-50,000 different strains.  Each strains of bacteria has the potential of producing a unique chemical that may influence how our body functions.  This mass of life is only beginning to be recognized as a potential factor in both health and disease.

The greatest concentration of bacteria are found within the last portion of the intestinal tract known as the distal colon.  As one moves upstream through the intestinal track, the concentration of bacteria markedly decreases.  There are very few bacterial within the upper portions of the small intestine.

The mixture of bacteria an individual carries within their intestinal tracts seems to be similar to the mixture of the individual’s mother’s mixture.  Other factors such as carbohydrate or fat intake, antibiotic use, exposure to animals or soil, fiber and total caloric intake can all influence the mixture of bacteria within our intestinal tract as well.

The Intestinal Tract is a Common Source of Problems

Many patients suffer from a variety of symptoms related to abnormal functioning of their intestinal tract.  These problems can last indefinitely and often seem to develop slowly over months or years without any obvious cause.

And more likely than not, the patient will be prescribed a new medication when they complain of one of the following symptoms:

  • Heartburn
  • Sour stomach or indigestion
  • Constipation
  • Diarrhea
  • Abdominal cramping
  • Urgent bowel movements after eating
  • Gas Pains
  • Bloating
  • Rapid fullness after meals
  • Recurrent vomiting
  • Poor appetite

Every one of these symptoms can be treated with a medication.  The patient is typically sent off for blood work, an abdominal CT scan or ultrasound as well as an upper endoscopy and colonoscopy from the local gastroenterologist.

The majority of the time these tests all come back normal and the patient is led to believe they need to stay on these medications for good.

More often than not, physicians are treating these symptoms without any real thought or concern about the underlying cause of the symptoms.

A Common Factor For Most of These Symptoms

To better understand these symptoms, you need to view the intestinal tract functions as a simple unidirectional conveyor belt.   Food enters the mouth at one end and then is methodically propelled forward from the mouth to the esophagus to the stomach to the small intestine to the colon to rectum then out.

What is common to all of these symptoms is that they can be triggered by poor forward motility of the intestinal tract.  If the conveyor belt-like action of the gastrointestinal tract is slowed so material is not pushed or passed forward quickly enough, these symptoms often occur.

With slowed forward motility, you may not develop all of these symptoms but many patients develop more than one.

Chronic heartburn, indigestion, bloating, and recurrent vomiting are often due to the stomach’s inability to empty its contents correctly.

Constipation and abdominal cramping are often due the inability of the intestines to propel their contents forward.  I’ve written before about how to improve these problems.

Intermittent diarrhea or the urgency to have a bowel movement shortly after eating are often due to an imbalance of bacteria in the intestinal tract from poor intestinal forward motility.

This imbalance of intestinal bacterial is called small intestinal bacterial overgrowth (SIBO) or less specifically Bacterial Overgrowth Syndrome (BOS).

I prefer to use BOS as it implies that bacterial overgrowth can cause inflammation and symptoms from both the small intestine and colon (otherwise known as the large intestine).  A more thorough review of SIBO and BOS can be found here.

Motility, Bacteria and the Intestinal Tract

Humans and the bacteria that normally reside in our intestinal tract have a symbiotic relationship.  That is, they both require each other’s presence to flourish and often survive.

Bacteria are essential in the breakdown of non-soluble fibers in our colon which release essential fatty acids and other nutrients that humans cannot digest and obtain on their own.  On the other hand, humans provide on hospitable environment (our intestinal tract) that allows several hundreds of different species of bacteria to thrive and replicate.

A variety of factors can disrupt the bacterial environment of the intestinal tract and results in an imbalance of bacteria. This bacterial imbalance results in an overgrowth of certain species of bacteria that are harmful in larger numbers.

Not only do they increase in number and pathogenicity, they also migrate upstream from the colon into the small intestine and cause inflammation and irritation of the small intestine.

This sequence of poor forward motility, bacterial imbalance and overgrowth with the ultimate migration into the small intestine is often the cause of symptoms in individuals who suffer from intermittent diarrhea or chronically have the urgency to have a bowel movement within an hour or 2 after eating.  Patients with frequent abdominal cramping (often diagnosed with Irritable Bowel Syndrome, IBS) frequently are suffering from BOS as well.

Symptoms can be so severe that patients lose a great deal of weight from the diarrhea, vitamin and mineral deficiencies (Iron, Vitamin A, Vitamin B12, Calcium) occur because of damage to the small intestines, the inflammation can become so great at times that patients are hospitalized because of the severe pain and dehydration.

Poor Intestinal Motility and Other Causes of Bacterial Overgrowth

There is a wide variety of disorders that cause bacterial overgrowth.  The most common is due to poor forward motility from impairment of the autonomic nervous system (I’ll discuss this I more detail below).  Other conditions may cause poor forward motility such as Scleroderma, Crohn’s Diseas, Amyloidosis, neurological diseases and Hypothyroidism.

Immune suppression (HIV Infection, poor antibody production, malnutrition) and medications such as antibiotics or proton pump inhibitors (Prilosec, Nexium, Protonix, Aciphex,etc) can all trigger bacterial overgrowth syndrome as well.

I’m emphasizing the autonomic motility perspective because it’s extremely common and often easily reversible with a simple change in diet.

Reversing Poor Forward Motility With Diet

The forward motility of the entire intestinal tract is under the control of the autonomic nervous system (ANS), specifically the parasympathetic and enteric branches.  I’ve written quit frequently about the ANS and a brief and accurate review can be found here.

Disruption of normal autonomic function is clearly associated with the systemic inflammation and metabolic disturbances associated with a common condition known as Insulin Resistance.

In fact, autonomic dysfunction seems to often precede the formal development of Insulin Resistance by many years.

Interestingly, studies are beginning to clarify a scenario that suggests the quantity carbohydrate (sugars and starches) consumption triggers the autonomic dysfunction.

A reduction in total daily carbohydrate intake to less than 100 grams per day can dramatically improve autonomic dysfunction within only 2-4 weeks.  Improved autonomic function will help the intestinal tract to regain its normal rate of forward motility.

Improved forward motility often results in the reversal of the entire list of symptoms review in the first section of the post.


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Patrick Nemechek, D.O.

Patrick Nemechek, D.O.

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Jim Purdy
Jim Purdy
February 9, 2012 4:09 am

Low carb seems to be the best diet for me.

January 14, 2012 3:21 pm

My heartburn and swollen ankles disappear when I cut back on my carbs. Over the holidays when I started eating what I wanted, it came back. I definitely believe that cutting back on carbs is best thing for my body.

Jim B
Jim B
January 11, 2012 10:14 pm

The heartburn, bloated stomach, indigestion and other related problems I’ve had for years disappeared when I worked on eliminating sugars from my diet. And boy how quickly they return with a piece of pie or cake ect.Lessons learned! Most important ,it didn’t happen over night….it was work. The reinforcement from this site is priceless. One more thing…..more recipes please.

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