SIBO, also known as small intestinal bacterial overgrowth, is a condition which has become more common in recent years. Due to an imbalance in gut bacteria, it can lead to unpleasant gastrointestinal symptoms, which can often be misdiagnosed as IBS. Read on to find out more about SIBO including what it is, the common symptoms and what you can do about it!
What is it?
Small intestinal bacterial overgrowth, or SIBO, refers to a condition where there is excessive amounts of bacteria in the small intestine. Normally there are a smaller number of microbes present in the small intestine compared to the large intestine. In people with SIBO, there is an increased number of microbes in the small intestine which would normally reside in the large intestine. These bacteria are responsible for the fermentation of the food we eat, such as fibre. When they are found in excessive amounts in the small intestine, it can lead to unpleasant gastrointestinal symptoms.
What are the symptoms?
Some common symptoms of SIBO are gas, bloating, abdominal pain and diarrhoea. Severe SIBO can also lead to nutrient deficiencies such as iron, vitamin B12 and vitamin D, however these often go undetected. Since the symptoms of SIBO are similar to common IBS symptoms, SIBO can be difficult to diagnose.
How do you diagnose SIBO?
A hydrogen breath test is commonly used to diagnose SIBO since the test is non-invasive and relatively simple. Hydrogen is produced when foods, such as carbohydrates, are digested by the bacteria within our digestive tract. An increase in the amount of hydrogen in the air we breathe out, after eating carbohydrates, may indicate there is excess bacteria present in the digestive tract.
The second, more invasive method of diagnosing SIBO is by taking a sample of the fluid from the small intestine. This fluid is then cultured in a lab to estimate the number of bacteria present. Whilst this method can lead to better diagnosis, it is more invasive than a breath test and therefore not as commonly used.
How do you treat it?
If you think you could have SIBO, you should seek the guidance of a medical professional, such as your GP and a dietitian. The most common treatment method, following a proper diagnosis, is a course of antibiotics to reduce the number of bacteria within the small intestine. A low FODMAP diet may be recommended following a course of antibiotics to reduce the number of fermentable products, or fuel, for the microbes which were residing in the small intestine.
SIBO and the low FODMAP diet
There is some evidence suggesting that following a low FODMAP diet leads to a reduction in SIBO symptoms. This is because a low FODMAP diet reduces the fermentable products in the food we eat. These fermentable products act as fuel for the microbes in our digestive tract.
It is important to remember, even with SIBO, you should not follow a low FODMAP diet long term. The strict elimination phase is only intended to last for 2-6 weeks, until symptoms are reduced, then challenges are recommended. The end goal of the low FODMAP diet is to determine your triggers. This allows you to re-introduce FODMAPs in the amounts which you can tolerate without gastrointestinal symptoms.
Pimentel, M., Saad, R.J., Long, M.D. and Rao, S.S., 2020. ACG clinical guideline: small intestinal bacterial overgrowth. American Journal of Gastroenterology, 115(2), pp.165-178.
Rasmussen, J. and Duriancik, D.M., 2019. Management of Small Intestinal Bacterial Overgrowth in Adult Patients. Gastroenterology Nursing, 42(3), pp.269-276.
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