If you’ve ever been on a medical odyssey to obtain a diagnosis for bothersome digestive symptoms, chances are someone along the way has ordered a stool analysis test for you. And for good reason: The simple act of pooping into a cup and dropping the sample off at a lab can yield a lot of diagnostic data. Your doctor can then use that information to help identify why you have diarrhea, gas, abdominal pain, unexplained weight loss or any number of other symptoms.
But increasingly, many labs are offering more detailed stool analyses that aren’t necessarily scientifically validated to diagnose any medical conditions. Many such tests deliver results on thick, colorful dossiers full of detailed information about patients’ stool. Read on to learn more about stool tests’ potential and limitations so you can better understand whether a test you’ve undergone – or been offered – is legit.
Stool Tests Can Help Diagnose:
- Pancreatic insufficiency.
- Fat malabsorption.
- Bleeding in the digestive tract.
- Certain infections.
- Inflammatory bowel diseases.
A stool test can tell clinicians whether your pancreas produces enough enzymes for proper digestion. Abnormally low levels of elastase in your stool can signal a condition called pancreatic insufficiency.
The tests can also help detect abnormally high amounts of fat in the stool, which are a sign of impaired digestion and fat absorption. However, knowing that you malabsorb fat is different than knowing why; the test alone cannot diagnose a specific disease.
Stool tests are also helpful in detecting blood in the digestive tract, which might account for low iron levels or be a warning sign of colon cancer. Newer stool DNA tests are also available to help your doctor screen for colon cancer.
Stool tests may also be appropriately ordered if your doctor thinks you could have an infectious diarrheal illness. A stool culture is used to identify possible bacterial infections, and these results can prompt more specific screening tests for particular bacterial toxins. A common lab test called an “ova and parasites exam” screens for a variety of non-bacterial microscopic parasites. Helicobacter pylori infection can be detected by stool testing, for instance; this is the bacteria better known for its role in causing stomach ulcers.
Finally, using stool tests to detect an elevated level of a protein called fecal calprotectin – a reliable marker for inflammation in the bowel – can help doctors understand if you may have (or have a flare-up of) Crohn’s disease or ulcerative colitis.
What Stool Tests Can’t Diagnose:
While stool tests can be an important tool in diagnosing many diseases, your poop does not offer a complete picture of your health. Reading poop, just like reading tea leaves, has its limits. Despite some companies’ and providers’ claims, there is no good scientific evidence that stool tests can diagnose the following:
- Celiac disease.
- Gluten or another food sensitivity.
- Food allergies.
- “Candida overgrowth.”
- “Leaky gut.”
Stool analysis is not a scientifically valid way to diagnose lactose intolerance, celiac disease, “gluten sensitivity” or any type of food allergy or digestive food sensitivity. Anyone who claims otherwise is stating a personal opinion that is not backed by evidence. Therefore, stool tests cannot offer any evidence-based recommendations about what type of diet you should follow.
And while stool samples offer a glimpse into what critters inhabit your colon, or the large intestine, they do not yield data on what organisms inhabit your small intestine, nor whether you have an abnormal number of them living there. Any practitioner who claims to diagnose a condition called small intestinal bacterial overgrowth (or SIBO) based on a stool sample is dabbling in what these days we call “alternative facts.”
“Dysbiosis” is a term often used to describe an unhealthy inner ecosystem of microorganisms in the gut; you’ll encounter it a lot in commercially available stool test results. However, it’s not a precise scientific term, and may be used to describe a variety of scenarios. For instance, it can mean relatively low levels of diversity of bacterial species in general, relatively low presence of certain species known to promote good health or relatively high abundance of species and strains associated with disease.
In addition to the lack of clarity around the term “dysbiosis,” there are two big problems with using stool microbiome tests to draw conclusions about your inner ecoystem’s balance. First, there is no single established standard for what constitutes a “healthy” gut ecosystem. Second, commercially available stool tests don’t provide the level of detail required for an accurate portrayal of what’s really going on among the the 1,000-plus different species or strains of organisms that inhabit your gut. At best, using one gives you a partial view of your inner ecosystem compared against an unknown reference range that may or may not be a relevant benchmark.
Beware, too, of stool tests that include specific commentary about your levels of a much-maligned yeast called Candida albicans – namely, whether you have too much of it. In reality, virtually every human being harbors this nearly ubiquitous yeast in his or her stool, and there’s no standard reference range for a “normal” level of it. Therefore, having “too much” of it is an arbitrary designation, often used as a pretense to sell you a probiotic or antifungal supplement regimen.
Lastly, stool tests that lead to a “leaky gut” diagnosis should raise red flags. For years, researchers have been investigating the junctions between intestinal cells and the barrier function they serve to keep bacteria from interacting with immune cells in the gut’s deeper layers. One protein at the center of this research is called zonulin, which is understood to play a role in our gut’s permeability or “leakiness.” But despite the preliminary state of this research and our nascent understanding of its implications, alternative health practitioners long ago packaged and marketed a condition called “leaky gut syndrome,” which is supposedly responsible for everything from digestive problems and food allergies to brain fog and joint pain. Some stool tests are already measuring zonulin levels and claiming they’re a marker for “leaky gut,” despite the absence of sufficient scientific evidence to link this protein to any specific disease or condition.