What is SIBO?

SIBO stands for small intestinal bacterial overgrowth. In other words, when there are too many bacteria in your small intestine.

When we think of the gut microbiome we tend to think of the trillions of microbes in our large intestine and the important role they play in our overall health. While this is true, the small intestine also contains its own distinct microbiome. It’s just that there are normally far fewer microbes living there. The types of microbes also tend to be different. So, essentially SIBO is too many of the wrong microbes in the wrong place.

Having a balanced microbiome in your small intestine is important, as this is where we absorb most of our nutrients. Not only that, the microbial community living there also plays a role in protecting us from harmful pathogens, helping to maintain a healthy gut lining and they even produce some micronutrients, such as vitamin K, which are key to a healthy immune system.

On top of this, when those extra microbes break down food coming from your stomach, gas is produced. This can lead to unwanted symptoms as well as interfere with your normal digestion by preventing you from absorbing essential nutrients in your food.

What Causes SIBO?

SIBO can develop for many reasons. The main cause is when normal intestinal motility slows down i.e. food moves more slowly through your gut. This prevents unwanted microbes from being cleared out and it means that undigested food hangs around for longer. There are several factors that can contribute to slow motility. It’s associated with age or may be inherited. Other disorders that are linked to dysmotility such as gastroparesis and hypothyroidism may also result in conditions in which SIBO causing flora can grow.

Those unwanted microbes can find their way into your small intestine, if you have low levels of stomach acid or if you’re not producing enough bile or digestive enzymes. Some researchers believe that the continued use of acid suppressors, like proton pump inhibitors (PPIs), can increase your risk of developing SIBO.  Also, there is a special valve or muscle found between our small and large intestine, which has a role in regulating the transport of undigested food between the two, as well as preventing waste material from passing back to our small intestine. For some this valve isn’t functioning properly and it can cause unwanted microbes to wander back to our small intestine.

Some of us also have extra nooks and crannies in our intestines due to conditions such as diverticulosis or from the after-effects of different types of small intestinal surgeries. This can make it easier for undesirable microbes to grow.

What Are the Symptoms of SIBO?

The common symptoms of SIBO overlap with other common digestive disorders. They include:

• Bloating
• Abdominal pain
• Diarrhea
• Belching
• Flatulence
• Constipation
• Unintended weight loss
• Fatigue
• Nausea
• Brain fog
• Loss of appetite
• Feeling uncomfortably full after eating

As you can see, SIBO causes a very broad list of symptoms. Some other signs that may indicate SIBO are:

• Symptoms soon after eating starchy foods – bacteria love easy-to-digest carbohydrates. We normally absorb these before they reach the large intestine. However, if you have any unwelcome visitors in your small intestine, they will be more than happy to digest them, rapidly releasing gas that may exacerbate your symptoms.
• Symptoms soon after eating high FODMAP foods – just like starch, FODMAPs are carbohydrates that bacteria can readily digest making you feel worse.
• Intolerance to prebiotics – Many people with SIBO will be able to tolerate prebiotics, but as these supplements are designed to feed bacteria, in some cases they may encourage the growth of the wrong ones rather than the right ones.

What are the long-term effects of SIBO?

We mentioned the short-term symptoms caused by SIBO but what happens if it’s left untreated? We know that our small intestine is where we absorb most of the nutrients from our food. So, when this process is disrupted, there can understandably be, negative knock-on effects on our overall health. With SIBO, the excess microbes are essentially competing with you for those nutrients, preventing your body from functioning at its best. The normal absorption of carbohydrates, proteins, and fats can all be disrupted. Over time this can lead to malnutrition and weight loss. In particular, deficiencies in some essential vitamins such as A, B12, D, and E as well as other micronutrients like iron can occur.

Next Up

Ok, that’s the basics covered. In the next blog in this series, we’ll take a look at how SIBO is diagnosed, treated, and managed. We’ll also see what the latest research says about SIBO’s links with IBS.