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What you need to know about Small Intestinal Bacterial Overgrowth (SIBO)

You may have been hearing or reading vague mentions about small intestinal bacterial overgrowth (SIBO) in your journey to improve your gut health. But what is it?

Initially, it was thought to only be present in people with anatomical conditions of the gastrointestinal tract. But it is now believed to be more prevalent in the wider community.

This is primarily due to better diagnostic testing availability. However, it is a poorly understood condition. And definitely a current hot topic amongst some researchers. To fully understand what SIBO is, we should first look at the place where it happens.

Role of the Small Intestine

The small intestine connects the stomach to the large intestine (colon/large bowel). The small intestine is sometimes referred to as the small bowel. This is where most of the digestion and absorption of nutrients takes place.

It also contains a vast network of specialised cells that help fight infections and regulate the immune system.

Microbiome bacteria are present throughout the entire gastrointestinal tract but in varying amounts. The type of bacteria typically present in the small intestine are different from those of the colon.

These beneficial bacteria in the healthy small intestinal microbiome perform essential functions. It helps protect against pathogenic bacteria (harmful bacteria) and yeast that has been ingested. They help the body absorb nutrients. And they produce several nutrients and vitamins like folate and vitamin K. The microbiome also helps maintain the regular muscular activity of the small bowel (peristalsis) so that food can move through the gut.

What is SIBO?

Small intestinal bacterial overgrowth (SIBO) is essentially an increase in the number of bacteria, and/or changes in the types of bacteria present in the small bowel.

In most people, SIBO is not caused by a single type of bacteria but an overgrowth of various types of bacteria that are usually found in the colon. Less commonly, SIBO results in an overabundance of the otherwise healthy bacteria of the small intestine.

SIBO has been shown to adversely affect both the function and structure of the small intestine leading to a myriad of problems.

Most of the gut bacteria are usually located in the large intestine. This is where it helps to break down the food that has passed through the small intestine for digestion and absorption purposes. The large intestine is also where vitamins are synthesized, and the elimination of waste occurs. So when there is an overgrowth in the small intestine, the excess bacteria feeds off the undigested food in the small intestine.

And wouldn’t you know it, they love modern diets full of sugar, simple and complex carbohydrates, and alcohol.

As the bacteria feed, it causes the carbohydrates to ferment. The fermenting process generates hydrogen as a by-product. This increase in hydrogen can feed a single-celled organism in the small intestine which produces methane as a result.

So, when you have SIBO, there are excess levels of hydrogen, methane, or both in your digestive system leading to damage and adverse symptoms.

What causes SIBO?

The body, because it’s incredible, has different mechanisms to prevent SIBO. These include gastric acid secretion, peristalsis, immunoglobulins in the intestinal fluid and a valve that allows the flow of contents into the colon. But this valve prevents it from traveling back into the small intestine. The cause of SIBO is usually complex and likely affects more than one of the protective mechanisms. The following factors usually contribute

  • Abnormally slow peristalsis
  • Low levels of gastric acid
  • Physical abnormalities of the small intestine
  • A weakened immune system

There are however several common risk factors that contribute to the development of SIBO.

Risk Factors

People with particular medical conditions are more likely to have SIBO.

  • Irritable bowel syndrome
  • Coeliac disease
  • Crohns disease
  • Diabetes mellitus (type 1 and 2)
  • Multiple courses of antibiotics
  • Organ system dysfunction such as liver cirrhosis, chronic pancreatitis or renal failure.
  • Prior bowel surgery

Damage to the nerves, gut wall or muscles in the gut from these conditions will increase the risk of SIBO by allowing an abnormal build-up of bacteria in the small intestines. This happens via several different mechanisms specific to the condition. Other risk factors for SIBO include:

  • Older age
  • Female
  • Long term uses of PPI (proton pump inhibitors – to decrease stomach acid)
  • Drinking alcohol
  • Recently completed a course of antibiotics.

These medications influence or disrupt the healthy gut flora. And of course, alcohol is full of the ingredients that ferment in the small intestine, giving ample opportunities for the microbiome to become unbalanced.


Depending on which gas is predominately produced, you can develop different symptoms and respond better to different treatments.

  • Hydrogen dominant SIBO typically leads to diarrhoea
  • Methane dominant SIBO is usually associated with constipation.

The overgrowth of bacteria also significantly interferes with the digestion of food and absorption of nutrients. This is primarily achieved by damaging the cells lining the small intestine (the mucosa). Other symptoms include:

  • belching, flatulence
  • severe bloating
  • abdominal pain or cramping
  • Food intolerances such as gluten, and lactose and particularly histamine intolerance.
  • Vitamin and mineral deficiencies, including vitamins A, B12, D and E
  • Fat malabsorption (signified by pale, bulky and smelly stools)
  • Rosacea and other skin rashes
  • Leaky gut.

Unfortunately, SIBO manifests differently in people. Some people may even go undiagnosed due to minimal physical symptoms being present.

Treatment and Prevention

In severe cases, Doctors treat SIBO by prescribing antibiotic therapy and recommending dietary changes. The broad-spectrum antibiotics can stabilise the gut microbiota by reducing the number of intestinal bacteria.

People who develop malnutrition or become dehydrated due to SIBO will also need nutrients and fluids. Which needs to be done under strict medical guidance.

Addressing the underlying condition leading to the disease is the only cure for SIBO.

Dietary changes are useful for managing SIBO, but there is little concrete evidence to confirm which specific diet is best. FODMAP diet may be helpful for people, but this should be undertaken with the help of a medical professional or certified dietician or nutritionist.

Prevention is a vital component of SIBO management. Dietary and lifestyle changes play a large part in preventing SIBO from returning.

Eating an abundance of plant-based foods and avoiding overly processed and sugary foods will allow good bacteria to flourish and stop unhealthy bacteria from overgrowing. Regular moderate exercise will help regulate the body’s digestive function.

Taking Gut performance™ daily promotes health and optimal gut function by healing, normalising and fortifying the protective lining of your digestive tract. It also contains prebiotics to help your naturally occurring microbiome to flourish.

Let us know via our Gut Performance™ Instagram page if you have tried Gut Performance™ and if it has had an impact on improving or reducing your pesky gut symptoms.

Works Cited

Dukowicz, A. C., Lacy, B. E., & Levine, G. M. (2007). Small Intestinal bacterial overgrowth: a comprehensive review. Gastroenterology Hepatology, 3(2), 112-122. Retrieved May 2019 Meyers, A. (2018, April). 10-signs-small-intestinal-baceterial-overgrowth. Retrieved May 2019, from Amy Myers MD: SIBO – what causes it and why it’s so hard to treat. (n.d). Retrieved May 2019, from Kresser Institute:

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