Small intestinal bacterial overgrowth (SIBO) happens when elevated bacteria are in the small intestine. Excessive bacteria here can affect digestion and absorption.
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However, bacteria can offer benefits, including:
- Micronutrient production
- Assisting metabolism or medicinal activation
- Bile salt biotransformation
- Indigestible polysaccharide fermentation
- Preventing luminal colonization by pathogenic microbes
Watch the webinar: Mastering Gut Health - Understanding SIBO
What causes SIBO?
A common cause of SIBO is normal intestinal motility dysfunction. Slow movement through the intestines promotes bacterial growth. Possible causes include:
- History of food poisoning
- Diabetes
- Some medications
- Damage to nerves
The underlying cause may also be unknown. SIBO has numerous consequences, including villi dampening, carbohydrate and protein malabsorption, and B12 deficiency.
How can SIBO be tested for?
The ‘Gold standard’ for diagnosing SIBO—culturing jejunal aspirate—has limitations. Numerous bacteria species do not grow in routine culture media, and the procedure is invasive and costly. The hydrogen breath test was designed due to the challenges of assessing the small intestine. It is utilized to detect SIBO and dietary malabsorption.
How can breath samples elucidate what is happening inside the intestines?
All cells produce carbon dioxide during metabolism, but only bacteria produce hydrogen and methane as metabolic by-products. These gasses transfer into the blood via the intestinal walls. When the blood reaches the lungs, a gas exchange happens, which allows for the detection of these gasses in exhaled breath.
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How to take a SIBO or malabsorption test
The GastroCH4ECK® Gastrolyzer® assesses the quantity of hydrogen or methane gasses in each exhaled breath. Before the breath test begins, the patient should adhere to a strict protocol. This includes a limited diet followed by a period of fasting. Not following the protocol may lead to a higher baseline recording or a false-positive result.
Before drinking the relevant substrate, a baseline breath sample is recorded. The substrate consumed is then mixed with 250 ml of water. The type of substrate corresponds to the test being taken. The substrates can be:
- Glucose
- Lactulose
- Sucrose
- Sorbitol
Breath samples are then recorded every 15 to 30 minutes, depending on the test. This process can take up to four hours, according to the test type. Depending on the type of test and the results, treatment may include antibiotics or changes to diet.
Fructose malabsorption
Fructose malabsorption is a dietary disability of the small intestine. Most people can absorb between 25 and 50 g of fructose at once. However, the small intestine of people with fructose malabsorption cannot adequately absorb fructose, meaning it then travels to the large intestine, where resident bacteria must metabolize it.
This then increases the quantities of hydrogen and methane gasses offset by the bacteria. Potential causes of fructose malabsorption include:
- Inherited or acquired abnormality of the fructose-transporting protein
- Excessive high fructose corn syrup or fruit juice overuse by children
- SIBO
- Celiac disease
- Radiation or chemotherapy
- Dumping syndrome
Clinical signs of fructose intolerance may include:
- Bloating
- Diarrhea
- Constipation
- Flatulence
There is currently no known cure for SIBO. However, a proper diet can help. High-glucose foods can help to absorb fructose.
To test for fructose intolerance, a patient must consume 25 g of fructose in 250 ml of water before recording breath samples every 30 minutes for three hours.
Lactose malabsorption
Lactose is typically hydrolyzed into glucose and galactose, then absorbed in the jejunum. Lactose should be hydrolyzed in the small intestine by lactase. If the lactase enzyme is deficient, the lactose will not be entirely hydrolyzed, leading to lactose malabsorption. Signs of lactose malabsorption may include:
- Distension
- Cramps
- Flatulence
Lactose malabsorption is the most widespread type of intolerance and affects around half the world’s population.
Watch the webinar: Mastering Gut Health - Understanding SIBO
Food allergies vs. food intolerances
People often confuse food intolerances with food allergies. A food intolerance may result from a change of routine, hormones, or eating out. The unpredictability of symptoms can disrupt someone’s life and cause them to avoid social activities. Many people who suffer from the condition turn to the internet for a quick and easy solution.
An intolerance happens when gut enzymes responsible for breaking down foods are lacking or defective or there is a problem with the mechanism that transports the molecules via the small intestine. Symptoms include:
- Abdominal pain
- Discomfort
- Diarrhea
Common food intolerances include:
- Lactose
- Fructose
- Sucrose
- Sorbitol
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It is essential not to self-diagnose, as numerous conditions have symptoms similar to irritable bowel syndrome and SIBO, yet they have different treatments and require different management strategies. It is always crucial to visit a doctor or healthcare professional for advice. A food intolerance may be diagnosed via an elimination diet or a breath test.
A key difference exists between a food intolerance and a food allergy. A food allergy is a reaction that involves the immune system. Symptoms can include:
- Rash
- Itching
- Breathing difficulties
People with food intolerance may be able to consume a small quantity of the food, while people with allergies should avoid these foods as eating them may be fatal. Food allergies can be tested via skin prick or an elimination diet.
Healthcare professionals currently do not recommend finger prick and hair analysis tests for food intolerances, as sufficient scientific evidence does not support them.
Breath testing is the preferred approach for identifying lactose malabsorption for multiple reasons. If patients proceed with an elimination diet and stop consuming milk, they might still consume lactose from multiple unsuspecting foods, including:
- Hot dogs
- Breaded chicken
- Sweets
Even if the patient tries to remove lactose from their diet, they may unintentionally ingest the substance.
Other test strategies may include:
- Endoscopic biopsies (invasive and costly)
- Blood test (repeated every 30 minutes)
- Stool acidity test (infants, young children)
Home breath testing devices
Home breath testing devices were more widely optimized following the COVID-19 pandemic to stave off waiting list delays and as people felt safer taking the tests at home. There are multiple advantages to home testing kits, including:
- Living far from the clinic and difficulty getting there
- Difficulty getting time off work
- Issues with childcare
- Difficulties leaving the house when experiencing symptoms
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However, a key limitation of home testing may be that the patient might not collect their samples correctly, meaning the test may need to be retaken. Patients should be given very clear and precise guidelines.
Many home testing devices are now available, but utilizing any one of these devices without the advice or guidance of a healthcare professional may lead to self-interpretation, misdiagnosis, and incorrect preparation, resulting in unnecessary avoidance of key food groups.
Home testing devices should be obtained from a reputable healthcare professional who can discuss the results or provide a report for the treating medical professional. This will ensure a suitable follow-up so the patient doesn’t develop a nutritional deficiency due to self-diagnosis.
Multiple factors are involved when diagnosing and treating gastrointestinal conditions.
Watch the webinar: Mastering Gut Health - Understanding SIBO
About Bedfont® Scientific Ltd
Bedfont® Scientific has specialised in the design and manufacture of exhaled breath and gas monitoring instruments since 1976.
For medical gas monitoring, their Medi-Gas Check medical pipeline testing range verifies not only the quantity but also quality of gas administered to patients.
Bedfont's breath analysers include carbon monoxide (CO) monitors such as the Smokerlyzer®, used for smoking cessation, and the ToxCO®, used by emergency services, to diagnose CO poisoning.
The NObreath® FeNO monitor provides accurate analysis of airway inflammation for the control of asthma, and the Gastrolyzer® range aids in the detection of gastrointestinal disorders and food intolerances. Quick and non-invasive, breath analysis is the new blood test.
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