Cartoon of digestive tract with bacteria and doctor, on yellow background for the topic of SIBO

Small Intestinal Bacterial Overgrowth is a common finding in people experiencing problematic gastrointestinal symptoms. Many common conditions and diseases are associated with SIBO, so this concept is important to understand.

Normal Gut Bacteria

Ordinarily, most bacteria are in the large intestine, housing billions of bacteria per millilitre of bowel content.

On the other hand, the small intestine has very little bacteria. The upper portion of the small intestine is sterile (no bacteria) and the lower portion has a small amount of bacteria.

Diagram of the digestive tract showing normal gut bacteria populations in the small intestine versus the large intestine

Defining SIBO

Small Intestinal Bacterial Overgrowth is defined as an increased number of bacteria in the small intestine [1]. This can include both good and bad bacterial overgrowth. To make a positive SIBO diagnosis, we expect about 1,000,000 bacteria per ml of proximal jejunal aspirate [1].

Two Types of SIBO:

Overgrowth of bacteria in the small intestine can come from two places:

  1. It comes down from the from the upper respiratory tract and oral cavity (gram-positive bacteria)
  2. It comes up from the large intestine

Symptoms of SIBO

Bacteria growing in the small intestine will ferment starches and fibers into gasses that damage the small intestine and cause a wide range of symptoms, not only in the gut but also systemically.

Gastrointestinal Symptoms of SIBO [1]

  • Bloating, gas, distention
  • Flatulence and/or frequent belching
  • Abdominal discomfort and pain
  • Diarrhea and/or constipation
  • Reflux
  • Leaky Gut

Systemic Symptoms of SIBO [1]

  • Signs of malabsorption (weight loss, fat in stool)
  • Joint pain
  • Polyneuropathy (comes as a result of B12 deficiency)
  • Acne rosacea
  • Macrocytic anemia
  • Iron-deficiency anemia

Risk Factors of SIBO

SIBO has been extensively researched over the last decade or so. We’re identifying more and more possible causes of SIBO and other diseases associated with SIBO.

Possible Causative Factors

  • Proton Pump Inhibitor (PPI) use [2] [3]
    • 50% of patients taking PPIs long term had SIBO vs only 6% of controls.
    • Long term is considered anything 36 months or longer
  • Gastric Achlorydria (Low stomach acid)
    • Due to acid blocking medications (PPIs) or autoimmune etiology [4]
  • Anatomical abnormality of the small intestine with stagnation
    • Due to small intestine diverticula, obstruction, surgical blind loop, radiation enteritis [4]
  • Opiate Pain Killer use [5]
  • Abdominal Surgical Patients (gastrectomy, cholecystectomy, hysterectomy)
    • Hydrogen producing SIBO is most common [6]
  • Chronic Pancreatitis
    • 1/3 of patients with chronic pancreatitis have SIBO [7]
  • Dysmotility [3]
    • Present in over 50% of subjects with unexplained gastrointestinal symptoms, including SIBO

Various Conditions are Associated with SIBO

    • IBS [8]
    • Irritable Bowel Disease
    • Crohn’s and Colitis [4][9]
    • Celiac disease [4]
    • GERD (with or without acid blocker use) [10]
    • Systemic Sclerosis  [4]
    • Rheumatoid Arthritis [11]
    • Scleroderma
    • Atherosclerosis
      • Link is to SIBO related vitamin K2 dependent mechanisms [12]
    • Diabetes [4][13]
  • Hypothyroidism [14]
  • Acne Rosacea [15]
  • Interstitial Cystitis [16]
  • AIDS [4]
  • Liver Cirrhosis [4]
    • SIBO present in up to 60% of patients with cirrhosis [4]
    • Non-alcoholic steatohepatitis (Non-alcoholic fatty liver disease) [4]
  • IgA Deficiency [4]
  • Combined Variable Immunodeficiency [4]
  • Fibromyalgia [4]
  • Restless Leg Syndrome [17]


Small intestinal bacterial overgrowth is a condition in which bacteria growth (where it isn’t supposed to be) produces a myriad of other issues, gut related and system wide. There’s a lot more in the discussion of SIBO, so be sure to read more about it here.


Interested in learning more?

Read on in our series of articles on Gut Health!

About the Author - Dr. Johann de Chickera

man facing camera

Dr. Johann is a fully licensed Naturopathic Doctor. His approach emphasizes the importance of living a healthy lifestyle and improving one’s health naturally. Dr. Johann obtained a Doctor of Naturopathy at the Canadian College of Naturopathic Medicine (CCNM). Education at CCNM is a vigorous four years, with a curriculum involving biomedical sciences, physical diagnosis, clinical nutrition, traditional Chinese medicine and acupuncture, botanical (herbal) medicine, physical medicine, homeopathy and lifestyle management.

While Dr. Johann has a general practice, he focuses on fertility, hormonal imbalances, gut health, and autoimmune disease.

To book in please call us at (519) 442-2206 or click here.

Leave a Comment