What is SIBO?

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Normally, bacteria are found in the trillions in the LARGE INTESTINE, where they perform various symbiotic functions for the human body.

SIBO is a condition where bacterial overgrowth occurs in the absorptive area of the body the SMALL INTESTINE.

The SIBO Breath Test

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We offer easy, affordable breath tests for SIBO and fructose malabsorption.

Find out if you have SIBO in four easy steps.

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Symptoms of SIBO can include:

  • Diarrhoea
  • Constipation
  • Alternating constipation and diarrhoea
  • Abdominal cramping
  • Bloating and/or wind
  • Burping and Acid Reflux/GORD
  • Food sensitivities
  • Joint pain
  • Skin rashes
  • Iron and B12 deficiency
  • Respiratory symptoms such as asthma

SIBO can occur when:

The ileocecal valve (which connects the large and the small intestine) is dysfunctional, allowing large intestinal bacteria to migrate upwards into the small intestine, where they wreak havoc.

The normal cleansing wave of the small intestine is disrupted, or stopped. This cleansing wave is called the Migrating Motor Complex (MMS), and occurs approximately every 90 minutes, typically between meals. The function of the MMC is to wash out accumulated bacteria and propel them toward the colon. The MMC is not related to the peristaltic waves of the large intestines.

The result is bacteria are allowed to grow and proliferate throughout the small intestine (a little over 6 meters in length).

How does SIBO affect you?

SIBO causes damage to the absorptive surface of the small intestine - the ability of the body to absorb nutrients from food.

The absorptive surface of the small intestine is likened to a shaggy carpet, with finger-like protrusions called villi. The surface of the villi contain microvilli, which act as the interface of absorption—microvilli secrete enzymes called “brush border enzymes” which break starches into single molecules and proteins into single amino acids, so these can be absorbed.

Small Intestine - absorbing nutrients from food

SIBO can result in:

  • Malabsorption of monosaccharides and amino acids (carbohydrates and proteins)
  • Fermentation of disaccharides by bacteria causing hydrogen, methane and hydrogen sulphate gasses
  • These gasses themselves are damaging to the gut wall
  • Malabsorption of vitamins (especially B12 and Folic acid)
  • Malabsorption of minerals (especially, magnesium, iron, and calcium SIBO can cause leaky gut, with a damaged gut wall allowing larger particles to pass through, causing an immune response

Causes of SIBO:

  • Post infectious: a case of gastroenteritis can often be the “heralding event” for the development of SIBO
  • Overconsumption of simple carbohydrates
  • Medications: proton pump inhibitors, morphine and other opiates, narcotics, possibly beta agonists and calcium channel blockers
  • Stress: chronic stress can decrease stomach acid output (hypochlorhydria).
  • Normal stomach acid levels are required to kill bacteria
  • Stress also causes changes in the motility of the small intestines, causing a pooling and stagnation which allows for bacterial overgrowth
  • Altered anatomy: malformation of the ileocecal valve, surgical intervention causing scarring and adhesions altering the normal anatomy of the small intestines
  • Initial colonization of bad bacteria: caesarean birth, no breast feeding

Associated conditions:

  • Fibromyalgia and Chronic Fatigue Syndrome – especially associated with diarrhoea dominant SIBO
  • Chronic constipation – associated with methane-dominant SIBO
  • Irritable bowel syndrome (IBS)
  • Inflammatory Bowel disease (Crohn’s disease and ulcerative colitis)
  • Acid reflux
  • Coeliac disease
  • Interstitial Cystitis
  • Restless leg syndrome
  • Acne Rosacea
  • Diabetes
  • Hypothyroidism
  • Scleroderma
  • Chronic Prostatitis
  • Non-Alcoholic Steatohepatitis (NASH)
  • Liver cirrhosis
  • Diverticulitis

Your Healthy Gut

Upper Gut: Digestion

The upper gut includes the mouth, oesophagus, stomach, pancreas and gallbladder and the first part of the small intestine.

Important facts about the upper gut:

Proper chewing ensures that food particles are broken down into smaller pieces, so stomach acid, pancreatic enzymes, and bile acids can act upon them. Hasty eating can cause bloating because of improper chewing.

Make sure you take a moment to relax before eating and take your time. If you are a fast eater, try eating with chopsticks. That is sure to slow you down.

Stomach Acid:

The normal acidity of the stomach is that of car battery acid! This serves several purposes:

  • The start of protein digestion: stomach acid breaks longer protein chains into smaller, more digestible polypeptides.
  • These are then further digested by enzymes from the pancreas and, finally, completely broken down by brush border enzymes in the small intestine

Stomach acid activates intrinsic factor—a substance which is released by stomach cells to help absorb B12.

Adequate stomach acidity is required for proper mineral absorption. If you are chronically low in minerals like zinc, iron, or magnesium, you may actually be stomach acid deficient.

Stomic acid is a natural antibiotic—it kills foodborne bugs. This is why people who are on acid blockers are more susceptible to food poisoning and “gastro bugs”!

Pancreatic enzymes – these are released into the first part of the small intestine—the duodenum, when the acidity of the stomach reaches a certain pH, along with other triggers.

Pancreatic amylase helps to break starches into smaller polysaccharides and disaccharides which are further broken down in the small intestine by the brush border enzymes.

Protease enzymes help to break the protein chains into smaller di and tripeptides.

Lipase helps with fat digestion.

Bile Acids:

  • Bile is a substance that is made by the liver and stored in the gallbladder.
  • Bile is released when the meal contains fat.
  • Bile helps to emulsify fat so it is better broken into smaller globules.

Small Intestine: Absorption

  • Your small intestine contains millions of finger-like protrusions called villi.
  • Imagine it like a rolled up shaggy carpet. On top of the fingers are even smaller fingers called microvilli—this is the single-celled interface we have with the inside of our body and the food that comes through.
  • Effectively, the villi and microvilli increase the surface area of the small intestine to that of a tennis court!

Facts About the Small Intestine

The microvilli release brush border enzymes which are the final step in protein and starch digestion. When these microvilli are damaged, so is your absorption of nutrients!

Besides malabsorption of lactose and fructose, certain vitamins and minerals also are also not absorbed.

The small intestine also contains 80% of our immune system. That means when undigested food particles are able to squeeze through a damaged gut wall, they come into contact with your immune system. This is how food allergies and “leaky gut” come about.

In between meals, your body sends a cleansing wave through the entire small intestines. This is called “the migrating motor complex”. It ensures that bacteria are swept downwards towards the colon.

Stress, medications such as opiates, and chronic anxiety can bring this cleansing wave to a halt. Bacteria are then allowed to stay in the small intestines and multiply, resulting in SIBO.

Facts About the Large Intestine

We contain more bacteria in the large intestine than cells in our body!

Large Intestine: Excretion

Your large intestine is responsible for water absorption as well as B12 and vitamin K absorption. It forms the stool and houses trillions of bacteria.

The colon is susceptible to “dysbiosis” – overgrowth of fungus, bacteria, or parasites. Fungal overgrowth (candida) is often caused by medications such as antibiotics.

The colon wall contains stretch receptors which stimulate the movement of the bowel when the stool is bulky.

Listen: Interview with SIBOTest Director Dr Nirala Jacobi ND


SIBO is the leading cause of IBS.

SIBO is a bacterial overgrowth in the small intestine that causes hydrogen, methane and/or hydrogen sulphide gas production. These gases cause the symptoms of IBS but also damage the intestinal wall.

Practitioners across the nation are familiar with the frequent presentation of IBS in their clients.

IBS can have several causes— food sensitivities, dysbiosis of the large intestine, lack of digestive enzymes or hydrochloric acid, stress. All can cause digestive complaints that are often indistinguishable from one another.

SIBO is actually a very common undiagnosed cause of IBS (up to 84%) and thus shares some of the same presenting symptoms with IBS—Gas/bloating, diarrhoea/constipation, and abdominal cramping.

The table below can help distinguish between IBS caused by SIBO and IBS from other causes.

Often better with fibre No Yes
Often improved with antibiotics Yes No
Better with probiotic containing prebiotics No Yes
Bloating after meals Within 5-20 minutes Often after a few hours
Onset after case of food poisoning Yes No

Do I have SIBO?


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We've developed a short quiz to help you discover if you may have SIBO

Results are instant and free.



The Breath Test for SIBO is Best Done With a Qualified Practitioner To Interpret Your Results

We ensure you find credible SIBO treating health care practitioners all over the globe. To find one near you - head to our Practitioner page and search for a team or medical professional near you.