What Is SIBO? Is It Giving You Digestive Woes?


Bacteria have been part of the human experience since the very beginning.


Ever since the germ theory of disease was accepted, we’ve been fighting bacteria in the hopes of ridding ourselves of every ailment known to humankind.


Bacteria have always been seen as something negative, but we know better.


Fast forward to today and we now appreciate the essential role bacteria and other microorganisms play in our well-being. It’s estimated that we host about 100 trillion of them in our digestive tract where they perform vital roles.


This includes protecting us from other microorganisms that can make us sick, stimulating our immune system, helping to digest food while synthesizing various nutrients.


Even though we live in harmony with our bacteria most of the time, there are situations where bacteria that are normally helpful, can be a problem. When that happens, our health can take a turn for the worse as is the case with Small Intestinal Bacterial Overgrowth or SIBO.


What is SIBO?

We have bacteria along the entire length of our digestive tract, from ‘snout to tail’ as they say.


The mouth, stomach and small intestines have relatively very fewer bacteria compared to the large intestine or bowel.


For example, the first 90% of the small intestine has between 1,000 and 10,000 organisms per one milliliter (one-fifth of a teaspoon) of intestinal fluid.


That number increases at the very end where the small intestine connects to the colon, the bacterial count there is 10,000,000 (10 million) organisms per same one milliliter of fluid. Things REALLY take off in the colon; some 1, 000, 000,000,000 (one trillion) organisms are jam-packed per milliliter of fluid in the large intestine.


When things go wrong

Under normal circumstances these proportions are maintained and health thrives. But there are times when things can go awry and the amount and type of bacteria in the small intestine can increase in number leading to bacterial overgrowth , a.k.a. ‘SIBO’.


It’s important to note that SIBO isn’t about an overgrowth of some kind of foreign strain or invader.


SIBO is the result of having too much of the bacteria that normally inhabit the small intestines and/or is caused when bacteria that normally resides in the bowel migrate up into the small intestine where they encroach on their newly found territory.


The location and concentration of bacteria throughout the digestive tract is very important when it comes to maintaining health; there relatively few throughout the length of the tract until the large intestine/bowel where there is a nearly incomprehensible amount of them: 1 trillion per ml or 5 trillion per teaspoon!!


With SIBO however, the ideal location and concentration of bacteria is anything but.


Woman holding her bloated stomach sitting on a bed - by Doug Cook RD

Why is SIBO a concern?

SIBO is more than just the inconvenience of symptoms which are listed below; if it was just a case of uncomplicated bloating, gas or occasional belching, it could be managed painlessly. The problem with SIBO is the bacterial impact on the digestive tract both in terms of the digestive tract’s structure and function.


SIBO causes a lot of digestive woes by damaging the gut. The bacteria produce metabolic waste that irritates the gut lining leading to inflammation; the inflamed gut tissue damages the enzymes that normally line the digestive tract that are needed to help digest the foods we eat leading to the maldigestion of protein, fat and carbohydrate.


Carbohydrate maldigestion is particularly problematic. Carbohydrates [sugars, starches, fibers]  that are undigested becomes a food source for the bacteria themselves which leads to a greater number of bacteria as they feed and populate leading to the overgrowth.


Remember that SIBO is partly the result of too many bacteria that are there in smaller amounts. The other problem stems from the bacteria’s ability to ferment the excess carbs in the gut which leads to excessive gas production.


Bacteria from the colon that gets into the small intestine can also be a contributor to SIBO which produce a lot of gas (CO2, methane and hydrogen) which increases internal pressure leading to reflux; this gas is also the source bloating and pain that comes with SIBO.


For anyone wondering if enough gas could be produced to cause enough pressure leading to excruciating pain and reflux consider this: just 30 g of carbohydrate (the amount found in an apple and a slice of bread or the weight of 6 nickels) is enough carbohydrate for bacteria to produce 10 liters (about 2 1/2 gallons) of gas!!!


The other problem is that many of the nutrients needed for health are preferentially used by the bacteria therefore reducing the amount of nutrients available for  absorption for the person with SIBO leading to functional and/or clinical deficiencies.

Bloated word cloud

SIBO symptoms

  • Post-prandial bloating specifically bloating up under the ribs
  • Gas
  • Belching
  • Intestinal pains/cramping
  • Diarrhea
  • Constipation
  • Indigestion
  • Heartburn
  • Nausea
  • Weight loss
  • Fatigue
  • Joint pain


SIBO causes

  • Scarring/strictures in digestive system
  • Low stomach acid (especially in the aging population)
  • PPIs [Nexium, Pantaloc], acid reducers [Zantac],  antacid use
  • Frequent use of antibiotics
  • Frequent steroid use
  • High stress lifestyle
  • Motility problems
  • Poor diet (high sugar, high carbohydrate)
  • Enzyme & bile acid insufficiency/deficiencies
  • Carbohydrate malabsorption


Conditions associated with SIBO

  • Diabetes
  • Liver or pancreas disease
  • Celiac disease
  • Non celiac gluten sensitivity
  • Inflammatory bowel disease
  • Hypothyroidism
  • Gastroparesis
  • Rheumatoid Arthritis
  • Irritable bowel syndrome
  • Chronic fatigue syndrome
  • Chronic constipation
  • Rosacea
  • Restless leg syndrome
  • Interstitial cystitis
  • Cirrhosis
  • Fibromylagia


Nutritional Implications

Functional and/or clinical nutrient deficiencies

  • Vitamin B12
  • Vitamin A
  • Vitamin D
  • Vitamin E
  • Iron
  • B-vitamins

SIBO treatment

Treatment begins with a comprehensive assessment of symptoms, risk factors and predisposing conditions that puts someone at risk for SIBO.


A thorough assessment includes a breath test to measure the gases expelled by the bacteria. The most common test is the lactulose or glucose breath test.  If there are too many bacteria, excess gases (hydrogen, methane or both) will be produced indicating overgrowth.


Some conventional and integrative/functional medicine practitioners will treat on the basis of symptoms without requiring confirmation from testing, as long as other digestive conditions have been ruled out.


Nutritional support includes various dietary modifications to help address the bacterial overgrowth, use of evidence-informed supplements to help address any gut inflammation and both functional and clinical nutrient deficiencies are also part of the healing strategy.


Various herbal antimicrobials or antibiotics protocols are also used by practitioners. Regardless, SIBO can be tricky to get rid of and any treatment needs to include addressing underlying risk factors to help prevent it from recurring. A simple round of antibiotics a few times a year has not been shown to help, a more integrative and holistic approach is needed.


Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, mental health.  Follow me on FacebookInstagram and Twitter.

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