Is your IBS really due to Small Intestine Bacterial Overgrowth?

If you regularly experience digestive symptoms such as bloating, flatulence, constipation, diarrhoea or pain, it is often labelled as Irritable Bowel Syndrome (IBS). This diagnosis can be frustrating, as it only confirms what you already know; you have a digestive issue of an unknown cause.  In my experience of working with people who have been diagnosed with IBS or other digestive disorders, there is usually an underlying issue.  In some instances, it is due to food sensitivities or an underlying parasite infection. However, there may be another cause that you have not considered – small intestinal bacterial overgrowth, or SIBO for short.

SIBO occurs when there is an excess of bacteria in the small intestine. These bacteria usually live in the large intestine and contribute to the overall balance of the digestive system, but they are not meant to live in large numbers in the small intestine. The overgrowth of this bacteria in the small intestine interferes with the normal digestion and the absorption of food.  They feed off specific carbohydrates found in foods called FODMAPs which cause the carbohydrates to ferment and release gases.  When this process takes place it can lead to significant discomfort.

SIBO is an issue for many people, especially those who suffer from IBS and other underlying conditions such as diabetes, immunodeficiency, Crohn’s disease and rheumatoid arthritis. In fact, as many as 84% of people diagnosed with IBS, have SIBO.

The overgrowth of the bacteria can also cause damage to the lining of the small intestine, leading to issues with leaky gut syndrome and deficiencies in nutrients such as Iron and B12. These deficiencies can lead to other health problems, such as anaemia.  The bacteria also feed on food that is unable to be absorbed due to the damage to the gut lining, which leads to more bacterial overgrowth and a decrease in the body’s ability to absorb fats.  This can lead to low levels of essential vitamins A, D, E and K, and cause issues with fatty stools.

Damage to the gut lining can result in larger food particles that are not fully digested to enter the body, which the immune system can react to, causing issues with food allergies and sensitivities.   The overgrown bacteria can also enter the bloodstream which the immune system then reacts to, which can be a burden on the liver and lead to issues with chronic fatigue and abdominal pain   These bacteria also excrete acids, which in high amounts can lead to neurological and cognitive issues.  Therefore, a problem in the digestive system can ultimately lead to other health issues such as autoimmune conditions, fibromyalgia, skin problems, and even depression.

The cause of SIBO

SIBO rarely exists on its own and what I find working with people with this condition is that there is usually an underlying issue in the digestive system such as low stomach acid production, low pancreatic enzymes, a weakened immune system, low thyroid function, or blood sugar irregularities.  SIBO can also be caused after experiencing acute gastroenteritis, food poisoning, or be a side-effect of using Proton-pump Inhibitors (PPIs) such Omeprazole or Lanzoprazole.


You can get tested for SIBO by doing a breath test to check for hydrogen and methane gases on your breath after swallowing either a lactulose or glucose solution.   The test is usually requested by your gastroenterologist or you can have yourself tested with a registered Nutritional Therapist who can request the test from a laboratory.

Treatment Options


Antibiotics work by attacking the bacterial overgrowth and are the first choice of treatment of most gastroenterologists.  Antibiotics are most likely to work if they are also complemented with dietary preventative measures as otherwise SIBO can return.

Herbal antimicrobials

A study undertaken at the Johns Hopkins University in 2014 found herbal therapies to be as effective as conventional antibiotics in treating SIBO. For this reason, this is often the preferred recommendation for naturally oriented practitioners.  Like with conventional antibiotics, herbal antimicrobials should also be accompanied by preventative dietary measures to ensure the complete and ongoing eradication of SIBO.


Unfortunately, eradicating SIBO with antibiotics does not always correct the underlying cause.  The bacteria can repopulate the small intestine within two weeks of finishing a course of antibiotics without also implementing preventative measures.  Alongside antibiotics or herbal antimicrobials, bile and pancreatic support is also necessary.  It is also important to manage stress.

Dietary Approach

There are a few diets that have been developed and are very successful in treating and preventing SIBO.  They include the Specific Carbohydrate Diet, the low FODMAPs diet, and the Gut and Psychology Syndrome (GAPS) diet.  The most effective way of addressing SIBO is by healing the digestive system by sealing the gut lining, rebalancing the good bacteria, improving stomach acid and pancreatic enzyme production, balancing blood sugar levels, and strengthening the immune system.

Here are a few ideas to get you started:

  • Stock up your freezer with grass-fed meat, poultry and wild fish. You will use these to prepare fresh stocks.


  • Learn how to make your own probiotics by fermenting foods such as home-made yoghurt, kefir, sauerkraut and other vegetables.


  • Prepare vegetables in advance for example butternut squash, courgettes, pumpkin, and broccoli by peeling, chopping and freezing them to use in soups, pancakes and stews.


  • Invest in a slow cooker, blender and juicer.


  • Experiment with soaking and sprouting pulses, nuts and seeds.

Embarking on a new way of eating only works when you are prepared.  Planning in advance with shopping lists, recipes and a menu plan is so important for your long-term success.  If you have been diagnosed with SIBO or would like to find out more about how to get yourself tested, please email me at so that we can  schedule a free 30 minute telephone call to discuss whether this may be suitable to you.


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