When too many bacteria, or a change in the type of bacteria usually present, populate the small intestine, it can lead to uncomfortable symptoms such as bloating, diarrhoea and constipation.

It can also affect digestion and absorption of nutrients from food, as well as affecting normal bacteria in the small bowel producing nutrients.

What is SIBO?

SIBO stands for Small Intestine Bacterial Overgrowth and its impact is typically more widespread than just digestive because the small intestine is also an important part of the immune system, containing cells that help fight infections and regulate the immune system.

Beneficial bacteria also help maintain the normal muscular activity of the small bowel, which creates waves that move the contents of the intestine, like food (known as peristalsis), through your gut.

Most of the focus when it comes to gut health tends to be on the stomach or large intestine. This vital section of the gut - the small intestine that connects the two together, and where a lot of hormones are secreted and nutrient absorption takes place is often overlooked.

How SIBO Interferes With the Gut & Digestion

SIBO has been shown to negatively affect both the structure and function of the small bowel.

It's also incredibly difficult to treat. I think this is partly due to its anatomical location within the digestive tract, hence its connections to so many other organs - like the liver, gallbladder, pancreas, stomach and large intestine which all play a part in preventing SIBO in the first place.

Structural Impact

Due to the overgrowth of bacteria’s ability to significantly interfere with digestion of food, mainly by damaging the cells lining the small intestine (the mucosal lining), Small Intestine Bacterial Overgrowth can lead to leaky gut which is a trigger for immune reactions and inflammation.

Nutritional Impact on Gut Function

Some of the nutritional problems caused by the pathogenic bacteria (in the case where there’s too many or the wrong types) are:

1. B12 Deficiency

Consumption of certain B vitamins, such as vitamin B12, before our own cells have a chance to absorb these crucial nutrients.

Often high levels of B12 will show up on a blood test even though essentially B12 is low or deficient due to the lack of absorption.

Too many of the wrong type of bacteria in the small intestine produce carbon copies of B12, which are useless to the body but show up on blood tests.

2. Too Much Ammonia

Overproduction of ammonia by certain bacteria increases the level of toxins in the body, as ammonia requires detoxification.

Ammonia is a neurotoxin produced by protein, but when in excess can lead to neuroinflammation, impairment of neurons, brain fog, impaired cognitive functioning and more.

It can also overload the liver and kidneys and produce other symptoms like headaches, irritability, fatigue, diarrheoa, and nausea.

3. Fat Malabsorption

Fat malabsorption due to bacteria consuming bile acid that is produced to help absorb fats, which inevitably can lead to deficiencies in fat soluble vitamins - A, D, E & K.

4. Festering Food Particles

The fermentation of carbohydrates and putrefaction of proteins brought about by a small intestine bacterial overgrowth can also produce a lot of gas as well as digestive symptoms that resemble irritable bowel syndrome (IBS)

5. Histamine Problems

Some bacteria produce histamine out of the amino acid histidine in the diet, which can cause an elevation of histamine in the gut and consequently histamine intolerance symptoms.

SIBO Symptoms

The most common small intestine bacterial overgrowth gut symptoms include:

• Acid reflux
• Stomach pain & discomfort
• Bloating and abdominal distention
• Diarrhea / loose stools
• Constipation
• Dyspeptic symptoms (flatulence, belching, nausea, heartburn)

Common non-gut associated small intestine bacterial overgrowth symptoms include:

• Brain fog
• Fatigue
• Joint pain
• Skin issues: acne, eczema, rashes, or rosacea
• Weight gain due to slower transit time of food through the digestive tract
• Weight loss related to nutrient deficiencies

Do I Have SIBO?

Research suggests that between 6 to 15% of  asymptomatic people have a small intestine bacterial overgrowth, while up to 80% of people with irritable bowel syndrome (IBS) have SIBO (1). In which case if you have IBS you likely also have SIBO.

Other than symptomatic identification of SIBO, which of course could be connected to other things too - like parasites, candida overgrowth or mold, the most common way to test for a small intestine bacterial overgrowth is functional breath testing.

Functional breath testing measures the levels of hydrogen or methane gas in the small intestine and can be organised by a Functional Medicine Practitioner, like myself.

High levels of hydrogen gas are typically associated with fast gut motility, and high levels of methane gas associated with slow gut motility. This isn't always the case though.

SIBO constipation or Methane SIBO is now known as Intestinal Methanogen Overgrowth (IMO) rather than SIBO. We’ll leave that for another blog post though.

Hydrogen sulfide gas is also associated with SIBO but there is no specific test to identify hydrogen sulfide presence and levels. However there is a way to interpret hydrogen sulfide in SIBO breath testing.

What's a Healthy Bowel Movement

As elimination is one of the most vital parts of preventing SIBO, what is a healthy bowel movement?

A daily, even twice daily bowel movement is key in preventing constipation SIBO. And then more than two bowel movements a day with runny stools or diarrhoea symptoms can be a sign of Hydrogen Dominant SIBO.

Stools need to take on the appearance of a formed smooth sausage. Anything up to three bowel movements a day is considered normal providing the consistency and colour are as they should be.

SIBO Risk Factors & Causes

There’s usually more than one cause of SIBO. When you consider the risk factors you’ll see why.

Risk Factors for SIBO

These risk factors are also an indication of what may cause a small intestinal bacterial overgrowth:

• Low stomach acid
• Irritable bowel syndrome (IBS)
• Celiac disease (long-standing)
• Chronic stress
• Bowel surgery or injury
• Inflammatory bowel disease (IBD)
• Diabetes (type I and type II)
• Moderate to heavy alcohol consumption (increased risk)
• Multiple courses of antibiotics
• Nervous system dysregulation
• Organ system dysfunction

Stress & SIBO

I’ve listed chronic stress as a risk factor and this is in my opinion the trigger that pulls the gun, setting off a cascade of dysregulation in the body, which essentially underpins everything else on the risk list too.

Stress hormones prevent the vagus nerve from turning on the relaxation response. If stress is ongoing, then the sympathetic nervous system will remain in overdrive, and communication between the gut and brain is disrupted.

The migrating motor complex is partly regulated by motilin (a digestive hormone), which is initiated by the vagus nerve. So, stress will inhibit the migrating motor complex as well.

The migrating motor complex (MMC) is a cyclic, recurring motility pattern that occurs in the stomach and small intestine during fasting.

This is why it’s good to avoid snacking and leave 4 hours minimum between eating so the MMC can do its job properly.

The Link between Bile & SIBO

Bile is a soap-like substance that aids in the emulsification of fats. Bile is also antimicrobial and helps to steralize and keep clean the terrain of the small intestine.

Having enough bile prevents bacteria in the colon from colonising the small intestine. Bile is one of your body’s ways of preventing SIBO. Stress will affect your production of bile too.

How to Increase Treatment Success & Prevent SIBO (Small Intestine Bacterial Overgrowth)

Now that you know more about the SIBO situation, you'll understand that a great way to help prevent SIBO and increase SIBO treatment success, is to support your digestive organs and the roles they play in removing and preventing bacterial overgrowth in the small intestine. This includes:

• digestive secretions of bile from the gallbladder
• digestive enzymes from the pancreas
• peristaltic contractions that move the contents of food through the small intestines - triggered by the vagus nerve
• liver for eliminating endotoxins produced when your gut is imbalanced, as in SIBO
• ensuring you have adequate levels of stomach acid, so that food can be broken down properly before it enters the small intestine

A lack of enzymes, bile, or other digestive secretions and hormones as well as reduced peristalsis greatly increases the risk of having small intestine bacterial overgrowth.

 

Ileocecal Valve

Another important barrier to bacterial overgrowth in the small intestine is the ileocecal valve that separates the colon from the small intestine.

This clever mechanical valve is designed to prevent too many of the bacteria residing in the colon to enter the small intestine. However this can weaken with age and become faulty from stress-induced events, like food poisoning.

Visceral manipulation can be extremely helpful for maintaining normal functioning of digestive sphincters (valves) including the ileocecal valve. It's a core part of my treatment programmes for those clients I see at my in person clinic.

 

I wish you all the best on your SIBO healing journey. Do reach out to me if you'd like my help.

If you’ve had SIBO or are struggling with SIBO and have something helpful to share about your experience, I’d love to hear about it in the comments section below.