Small Intestinal Bacterial Overgrowth and IBS

Ten to 25 percent of Americans who complain of digestive issues (acid reflux, bloating, nausea, gas, and so forth) are diagnosed with Irritable Bowel Syndrome (IBS). Because this condition affects so many individuals, and can impact quality of life, it is important for us to understand the underlying causes. One of these potential causes is Small Intestinal Bacterial Overgrowth (SIBO), which studies have shown affects up to 84 percent of IBS sufferers.


Digestion begins in our mouths. Upon smelling the aroma of food, our brain signals digestive juices to release and we start salivating. If we chew properly, our digestive enzymes start breaking down food. Once swallowed, food travels down the esophagus and to the stomach.

There, stomach acid (also known as hydrochloric acid) enters to help continue to break down our food and prepare for the next steps of nutrient absorption.

After the stomach, food enters the small intestine, which, at about 20 feet long, is not that small. Here, pancreatic enzymes and bile acids break food down into nutrients that our bodies can absorb and utilize. In a healthy person, it takes food about two hours to move through the small intestine and into the large intestine. The small intestine is home to only thousands of bacterial organisms whereas the large intestine is home to trillions.

The large intestine is only six feet long, but much wider than the small intestine. Its major function is absorbing water from bowel remnants, neutralizing acid, absorbing some nutrients, and disposing waste.


As mentioned, SIBO is a contributor to IBS. SIBO is a condition where bacteria overgrow in the small intestine and become problematic to its function of absorbing nutrients and moving food along, causing these symptoms:

  • Abdominal bloating
  • Abdominal pain and/or cramps
  • Gas (passing gas and/or burping)
  • Diarrhea and/or constipation
  • Heartburn
  • Nausea
  • Chronic nutrient deficiencies

This condition is typically caused by damage to the digestive system’s own nervous system, which dictates the movement of food through the digestive system. This damage either slows down the process, speeds it up, or an alternation of both. These symptoms can be debilitating to a healthy and balanced life because the overgrowing bacteria feeds on your food, draws water into the small intestines and causes the symptoms listed above. If these symptoms are persistent for at least three months, SIBO can be the culprit.

Causes of this imbalance can include:

  • Food poisoning
  • Medications including pain relievers, birth control, and antibiotics
  • Conditions that cause constipation like hypothyroidism
  • Exposure to contaminated water
  • Pathogens
  • Previous digestive or pelvic surgeries
  • Other digestive issues like celiac disease


In addition to digestive disturbances, SIBO has been found to affect many other systemic conditions including:

  • Rosacea and skin rashes
  • Hypothyroidism
  • Rheumatoid arthritis
  • Diabetes
  • Diverticulitis
  • Parkinson’s disease
  • Restless Leg Syndrome
  • Crohn’s Disease and ulcerative colitis
  • Celiac disease
  • Gluten/lactose Intolerance
  • Leaky Gut Syndrome
  • Anxiety/depression
  • And more …


The bacteria in the small intestine emits gases (hydrogen, methane, and sulfide) that are released via our lungs, so the potential bacteria overgrowth is measured by a breath test. It is a simple at-home test that is conducted over two to three hours.


Traditional treatment is antibiotics to eradicate the bacterial overgrowth and medications to restore normal movement of the bowels to avoid recurrence. Unfortunately, this condition has a high rate of recurrence making it frustrating for both patients and providers. SIBO is considered to be a secondary condition to the potential causes listed above, so it is important to understand the underlying cause for successful treatment.

Alternative medicine offers herbal therapies that have been shown in research to be effective in bacterial eradication in antibiotic-resistant cases. It also recognizes that other imbalances may be happening concurrently.

Both conventional and alternative practitioners agree that diet modifications are necessary to maintain results. The diet prescribed is a called a Low FODMAP diet, which restricts the foods bacteria typically feed on and limits their ability to regrow in the small intestines.

Eventually with full eradication and correction of the underlying cause, the goal is to transition patients back to a normal healthy diet.

When I started treating SIBO about five years ago, it was very new information to the patients I was working with. In the last year, people are gaining more familiarity of the condition and how it is impacting such a wide array of conditions. If you are affected by IBS symptoms, this may be something to discuss with your doctor.

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Thalia Farshchian is a naturopathic doctor at Discover Health. Her background includes both conventional and alternative modalities, and her practice is primarily focused on weight management, hormone imbalances and gastrointestinal conditions. E-mail: [email protected]