Why does SIBO cause bloating?

How could SIBO cause your bloating?

Are you sick of being mistakenly congratulated on your pregnancy? If you struggle with constant bloating then small intestine bacterial overgrowth (SIBO) could be contributing to the stomach distension and excessive gas.

As a nutritional therapist working with people who have SIBO, bloating is the main complaint I hear about from my clients.

Bloating is a common symptom in SIBO

Apart from bloating, other common symptoms of SIBO include abdominal pain, nutrient insufficiency (e.g. B12 or iron), aching joints, excessive gas, belching, diarrhoea or constipation.

Our small intestine is where nutrients from our diet is absorbed, and this is often where bloating can begin if food is not properly broken down and absorbed.

Malabsorption can be caused by several things such as:

• Damage to the villi – villi are small finger like protrusions in the intestines which help absorb nutrients and they can be damaged in untreated coeliac disease, inflammatory bowel disease, alcohol misuse, scarring, or other causes of damage to the gut.
• Insufficient chewing – large chunks of food take more chemical processing inside the gut. This is the reason I wrote about why chewing is so important.
• Digestive enzyme insufficiency  – we have enzymes which break down fats, protein and carbohydrates. The bacteria particularly love carbohydrates, and if these may be triggers of your symptoms like bloating, gas, stomach cramps or diarrhoea. Bacteria can damage the brush boarder enzymes, so our body doesn’t break it down as well. High chronic stress or anxiety can also reduce levels of digestive enzymes. So this leaves more food sitting in the small intestine.

 How does SIBO cause bloating?

When carbohydrates are left in the small intestine it can be food for bacteria living there. The small intestine shouldn’t normally have a large amount of microbes, but they can start to overgrow if you have issues such as slow gut motility, poor diet, surgery, adhesions or medication.

So when these bacteria start to eat the carbohydrates they produce gas. This gas can be hydrogen, methane or hydrogen sulphide.

Gas in your small intestine may take a long time to come out, and can really add to bloating. You may also get abdominal pain from the stretching of the intestines.

Bacteria in the small intestines

Bacteria in our gut love to eat carbohydrates. They ferment the food we eat causing gas. 

However, this doesn’t mean you shouldn’t eat carbohydrates. Here are three important reasons

• Firstly, we need to feed the bacteria in our large intestine with fibre and starches in carbs. Fibre also helps regulate bowel movements, reduces the risk of heart disease, maintains a healthy weight and so much more! 
• And secondly reducing carbohydrates won’t get rid of the SIBO, so cutting out carbs on it’s own won’t improve your digestion long term. You need to look at the causes of SIBO, and reduce the bacteria (more on that below).
• Lastly, carbohydrates are a fantastic source of energy, and removing them from your diet long term may leave you feeling tired, hungry and miserable.  

As a quick reminder here is a list of foods containing carbohydrates:

• Grains – bread, pasta, crackers, rice, oats
• Vegetables
• Nuts and seeds
• Fruits
• Sugars and sweeteners – honey, sugars.
• Lactose in milk

Difference between SIBO and carbohydrate malabsorption

Here’s a super quick summary and then I’ll explain it in more detail below

• SIBO symptoms are caused by bacteria fermenting foods in the small intestine. 
• Carbohydrate malabsorption symptoms are caused by a poor digestion and absorption of the sugars (e.g. fructose or lactose)

Some people struggle to digest sugars in our food such as lactose in dairy, or fructose in plants, due to an inability to break them down. We need to break our food into smaller molecules to be absorbed into our intestinal cells.

For example, you may feel more bloated with dairy in your diet, which could be lactose malabsorption.

Lactose is found in milk, cheese or yoghurt. When we eat lactose containing foods an enzyme  called lactase breaks down lactose into glucose and galactose so it can be taken into the cells.

If you don’t have enough lactase some of the lactose stays whole. A larger molecule of lactose then travels to the large intestine. 

This can cause bloating and gas as the large intestine bacteria ferment the lactose. This process can also draw more water in the large intestine which may trigger diarrhoea or more bloating.

Can improving SIBO reduce bloating?

 The good news is that reducing SIBO can improve the levels of enzymes in your small intestine. Which means you could reduce the symptoms of carbohydrate malabsorption. 

The key is reducing the amount of microbes causing the excessive gas.  

Your SIBO driven reaction to foods is individual

Unfortunately there is no standard set of symptoms, or treatment plan with SIBO. This is because:

• Different bacteria all like different types of sugars, so not everyone will react to the same foods, or react in the same way
• Depending on the location of your small intestine overgrowth will depend on your reaction times and types to different foods. For example if the overgrowth of bacteria are in the upper part of your small intestine you might get a reaction quicker than if the overgrowth is lower down.
• How much damage you have to the brush border enzymes
• Your overall health – do you have good stomach acid levels, do you have other conditions or take medication

Should you go low carb during SIBO treatment?

The way to treat and overgrowth of bacteria in the small intestine depends on your symptoms, your budget, your lifestyle, your current diet and more!

Most approaches to SIBO include some kind of agent to reduce bacterial overgrowth, whether that is through antibiotics or herbal antimicrobial supplements. You need advice from a nutritionist or doctor on the best approach for you and your situation.

There are two dietary approaches for managing SIBO either

• Feeding the bacteria so killing them whilst they replicate
• Reducing the food for bacteria so there are less to kill off

You’ll see specialists recommend either of these options, so it’s not always clear in what order to follow all these recommendations. Especially if you’re trying to figure this out on your own.

With my clients it depends on how significant the bloating is, and how much it’s affecting their life. Reducing the symptoms of bloating can be done by reducing carbohydrates, because it takes away the food for the bacteria. 

Read more about SIBO diets and what to eat with SIBO.

But this alone doesn’t resolve the overgrowth, so you’ll need a full treatment protocol, including looking at lifestyle elements such as sleep, eating patterns, stress management and timing of food.