You see patients in your office with chronic digestive issues, such as bloating, gas, diarrhea, and abdominal cramps all the time. First, you may want to rule out irritable bowel diseases and other serious gastrointestinal issues. At this point, many doctors may diagnose their patients with irritable bowel syndrome (IBS). But there are some other underlying issues you may want to test your patients for.
About ⅓ of people with IBS and other vague, chronic gut symptoms are dealing with underlying small bacterial overgrowth (SIBO), lactose intolerance, fructose malabsorption, sucrose intolerance, or sorbitol sensitivity (1). Fortunately, it is very easy to test for these issues with a simple (and affordable!) breath test that can actually help your practice be more efficient and productive.
So what is breath testing, and how can you benefit from this at your practice? Let’s dive in.
What Is Breath Testing
Hydrogen-methane breath testing, or simply put, breath testing, is a simple diagnostic test to measure the hydrogen (HO2) levels in the breath the patient exhales. Breath testing is a fantastic method to diagnose a list of gut health issues, including small intestinal bacterial overgrowth (SIBO), lactose intolerance, fructose malabsorption, sucrose intolerance, and sorbitol sensitivity. It may help to identify underlying issues behind irritable bowel syndrome (IBS) and other digestive issues.
There are different types of breath tests. Each of them measures the digestion of different sugars to identify specific health issues. In cases of intolerances, different tests test for specific sugars, including lactose, fructose, sucrose, or sorbitol, looking at carbohydrate malabsorption issues. The breath test for SIBO helps to identify bacteria overgrowth in your small intestine. This happens if bacteria from your colon move up to the small intestine, where they shouldn’t be.
The results of a breath test will allow you to confirm or rule out certain causes of digestive symptoms and certain diagnoses in your patients. Needless to say, incorporating breath testing into your practice will help practitioners, like yourself, to come up with proper treatment strategies based on your patient’s breath test results.
Principles of Breath Testing
Let’s talk about the principles of breath testing in more detail. Sugar molecules are usually metabolized in the small intestine. What does this mean? Glucose gets absorbed directly, just like fructose.
Both glucose and fructose are single-molecule carbohydrates, also known as monosaccharides. Two sugar molecules of disaccharides, such as sucrose and lactose, get split by enzymes that are present in the small bowel lining, and the resulting single sugar molecules are then absorbed in the small intestine.
When we are dealing with a gut health issue, in many cases, we are dealing with an abnormality in these processes. Abnormalities in the process may lead to various issues. Sugars may end up getting metabolized by bacteria either in the small intestine, as seen in SIBO, or in the colon when the small intestine is unable to absorb sugar.
This may lead to abnormally high production of hydrogen, methane, and in some cases, hydrogen sulfide. (To learn more about the significant measurement and interpretation problems with using hydrogen sulfide breath tests, hear more from Dr. Martin Hahn, the CMO at AllClear Healthcare in his webinar on “Hydrogen/Methane Breath Testing”). The absorption of any of these gasses into the bloodstream will be then exhaled through the breath.
This is exactly what lab analysts are looking at during breath testing. Through breath testing, we are able to measure breath samples with a gas chromatograph. We use this to test for abnormal carbohydrate metabolism. Breath testing generally requires a collection of several breath samples, first at baseline and then at regular intervals. The goal here is to challenge the digestive system with the dose of a specific sugar. Once we have these samples, we can look at gas measurements over three hours to identify any abnormal increases in gas concentration.
In a healthy gut, bacteria is normally limited to the colon. Most of the bacteria entering the body from food is usually killed by the acidity content of the stomach. As a result, unlike the colon, the small intestine tends to have very few bacteria in it.
However, in the case of SIBO, there is a higher concentration of bacteria in the small intestine, too, causing a list of symptoms and health complications. Why? Too many bacteria in the stomach can interfere with the absorption of sugars, vitamins, and various essential nutrients. The result is usually vague and chronic gastrointestinal (GI) symptoms that often get the IBS label.
However, the issue is often not “just IBS”. The causes and symptoms are not mysterious or unknown. If there is a bacterial overgrowth in the small intestine causing symptoms, it is important to figure it out and get the right diagnosis for proper treatment. Bacterial overgrowth in the small intestine can lead to increased gas production of hydrogen, methane, hydrogen sulfide, or all three due to the ingestion of specific sugar substrates and the fermentation of these sugars by the bacteria in the small intestine.
SIBO is not the only issue that may cause similar chronic digestive symptoms. In lactose intolerance, for example, there is a different mechanism that may lead to the increased production of gasses. If in a sugar like lactose, the two sugar molecules (disaccharide) are not split by the lactase enzyme, the small intestine won’t be able to absorb and metabolize it properly. As a result, it will pass into the large intestine, getting exposed to bacteria in the colon.
When this happens, fermentation and an increase in gas production can occur. So we will see abnormal breath test results after a lactose challenge in patients that partially or completely lack lactase enzymes. The same will occur in fructose malabsorption, sucrose intolerance, and sorbitol sensitivity.
Thus using different sugar substrates during breath testing allows us to identify various disorders of carbohydrate metabolism or SIBO, narrowing down on the root cause of the symptoms. We also have different tests and substrate sugars to use to test SIBO and other issues in diabetics without causing high blood sugar problems and increasing diabetes symptoms. Though using lactulose instead of glucose is less accurate, many studies suggest may be safer for those with diabetes. In adults, we use standardized substrate amounts for SIBO testing, with the exception of children or very small adults, where we use a weight-based dosing regimen. In most adults, the intestinal length and absorptive capacity do not differ much from person to person regardless of size or weight, so standardized doses work well.
Indications of Breath Testing
There are a number of health issues that you may use breath testing for proper diagnosis. Here are the main reasons you should consider breath testing and what breast test to choose:
- Lactose intolerance or malabsorption: Lactose breath test
- Small intestinal bacterial overgrowth (SIBO): Glucose breath test and for diabetic patients lactulose breath test
- Fructose malabsorption: Fructose breath test
- Sucrose intolerance: Sucrose breath test
See the Symptom Checker
Common Symptoms
When you look at the symptoms of the common health conditions that may prompt for a breath test, you will notice that these symptoms are often very similar. They are usually chronic and often vague.
The common symptoms that may warn for breath testing may include:
- Bloating
- Loose stools and diarrhea
- Gas
- Nausea, especially after certain foods (it may be a delayed symptom)
- Abdominal cramps
- Abdominal pain
As you may notice, these are all very common symptoms that frequently get labeled as irritable bowel syndrome (IBS). There is no specific test for IBS. It is a diagnosis of exclusion. If patients have these symptoms, doctors may diagnose their patients with IBS if they don’t see any other clear reason for their complaints. In reality, a number of these “IBS patients” may have underlying issues, such as SIBO or lactose intolerance, which we can easily test for with a simple breath test.
When sugars get fermented instead of being absorbed properly, it can cause bloating, gas, loose stools, nausea, cramping, and other common GI symptoms. As practitioners, we see these all the time. Patients with these symptoms commonly receive the IBS diagnosis. You are probably not surprised to hear that according to a 2020 meta-analysis published in Clinical Gastroenterology and Hepatology, about 1 in 10 people are diagnosed with IBS, and one-third of them have IBS with constipation (IBS-C) (2).
The problem is that many practitioners don’t realize they have the tools to dig deeper. At other times patients accept the IBS diagnosis without understanding the cause of the issue. Yet, in many cases, SIBO or a carbohydrate metabolism issue is behind the problem. In a 2023 review published in the World Journal of Gastroenterology, 33.8% of patients with an IBS diagnosis had underlying SIBO (1). An earlier, 2020 meta-analysis published in the World Journal of Gastroenterology has found that 36.7% of patients with IBS also had SIBO. Patients with IBS were 2.6 – 8.3 times more likely to test for SIBO than the healthy control group without IBS (3).
Moreover, there are many studies that show that lactose intolerance and other disorders of carbohydrate metabolism are commonly present in SIBO. According to a 2010 study published in Alimentary Pharmacology & Therapeutics, 87% of patients with chronic functional diarrhea (CFD) had lactose intolerance (4). Many also had SIBO. According to a 2011 study published in the Saudi Journal of Gastroenterology, SIBO and lactose intolerance may be both common underlying issues in IBS (5).
A 2018 study published in the Journal of Neurogastroenterology and Motility, has found that 45.7% of patients with IBS but without SIBO had fructose malabsorption issues (6). A 2022 research published in Proceedings (Bayer University, Medical Center) has found sucrose intolerance in about one-third of IBS patients (34.4% and 40% in two different hydrogen-methane breath tests and 26.5% with a C-sucrose breath test) (7). A 2022 systematic review and meta-analysis published in Scientific Reports has found that 47.3% of patients had sorbitol malabsorption (8).
Looking at these studies and the efforts of those with experience testing patients for these issues, it seems that many patients with SIBO, lactose intolerance, and other carbohydrate metabolism issues are just told they have IBS. They end up dealing with chronic symptoms for years or a lifetime without receiving a proper diagnosis or treatment.
Taking the time to do some simple breath tests to rule out or confirm SIBO or disorders of carbohydrate metabolism could make a difference for patients since these issues can often be dramatically improved with the right diet, enzyme supplementations, or other more targeted treatment. AllClear Healthcare offers innovative, accurate, and affordable at-home, mail-in tests, you can prescribe your patients to support making this process more convenient and faster, and to further support accurate diagnosis and proper treatment.
Moreover, breath testing may be important for people even with other more significant illnesses, such as Crohn’s disease or ulcerative colitis. SIBO and disorders of carbohydrate metabolism are also common in IBDs and other more serious gut health issues. For example, according to a 2019 systematic review and meta-analysis published in Alimentary Pharmacology & Therapeutics, SIBO was 9.51 times higher in patients with Crohn’s disease and ulcerative colitis compared to the control group (9). The odds were even higher in patients with a history of intestinal surgery.
Common Underlying Causes
Before we move on to some recommendations on choosing the right breath testing method, let’s go over the common underlying causes of SIBO and carbohydrate metabolism.
Common underlying causes of SIBO and carbohydrate metabolism may include:
- Ethnicity, especially in lactose intolerance and fructose malabsorption
- Celiac disease
- Food intolerances, both genetic or acquired
- Antibiotic therapy
- Achlorhydria, in which the stomach doesn’t produce hydrochloric acid, due to age, medication, surgery, or other factors
- Diabetes
- Hypothyroidism
- Irritable bowel syndrome, where motility issues may lead to overgrowth
- IBDs, including Crohn’s disease and ulcerative colitis
- Scleroderma
- Fibromyalgia
- Intestinal cystitis
- Liver cirrhosis
- Diverticulitis or diverticulosis
- History of bowel surgery
Let’s look at these common risk factors and causes of SIBO and carbohydrate metabolism a bit closer.
Ethnic background is one of the important factors we need to consider. Lactose intolerance is common in Asian and Middle Eastern countries, African Americans, and Jewish and Italian heritage (10). Celiac disease is common in non-Hispanic white individuals, especially with Scandinavian, German, Italian, and Celtic heritage (11). This may lead to damage in the small intestinal mucosa and loss of sugar-splitting enzymes. Therefore, it is commonly associated with lactose intolerance. In fact, in patients with Celiac disease, a gluten-free diet alone may help to restore the small intestinal mucosa and improve lactose intolerance as well (12, 13).
GI infections or antibiotic therapy may lead to temporary enzyme deficiencies that may increase carbohydrate metabolism issues. Reduced gastric acid due to older age, the use of certain medications, or surgery may also increase the risk of SIBO (14). In achlorhydria, the lack of acid production in the stomach may allow bacteria to enter and colonize the small intestine. This may happen due to anti-reflux or antier medications. In some cases, we may see this with probiotic therapy as well.
The common theme in the other factors listed, including diabetes, hypothyroidism, IBDs, scleroderma, fibromyalgia, intestinal cystitis, liver cirrhosis, diverticulitis, diverticulosis, or a history of bowel surgery, is motility problems in the bowel and stagnation of the small bowel content may provide an opportunity for abnormal bacterial overgrowth (15, 16, 9, 17, 18, 19, 20, 21, 22). In IBD, we may see scarring impairing normal motility. The same thing may happen in scleroderma, diverticulosis, or after bowel surgery. Stagnant areas in the bowel are also at risk of developing bacterial overgrowth.
Final Thoughts
Many patients with IBS and other vague, chronic gut symptoms are dealing with underlying small bacterial overgrowth (SIBO), lactose intolerance, fructose malabsorption, sucrose intolerance, or sorbitol sensitivity. Fortunately, it is very easy to test for these issues with the help of breath testing.
AllClear Healthcare Hydrogen/Methane testing is (to our knowledge) one of the most accurate, easy-to-use, and affordable test options available today. It’s simple to use for your patients with straightforward results that can help you, as a practitioner, to offer the right diagnosis and the best treatment possible.
