Charlotte Hunter, Registered Nutritional Thereapist at Regenerus Labaratories, discusses stool testing. Charlotte is part of the Regenerus Clinical Support team and is the founder of The Nourish and Flourish Club and The Yummy Tummy Club. She is currently working towards becoming a Certified Functional Medicine Practitioner with The Institute for Functional Medicine.
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The when, what and why of stool testing?
Back in 400 BC Hippocrates stated how “death sits in the bowels” and the more we know, the more we grow to view the gut as the epicentre of good health. Stool testing is undoubtedly the number one diagnostic tool for functional medicine practitioners, but really the three most popular options are: OAT (Organic Acid Test); SIBO (Small Intestine Bacterial Overgrowth) and CSA (Comprehensive Stool Analysis). In some cases, it may be obvious which test to choose, based on the presenting signs, symptoms and medical history but in some more complex patients, where should you start? To help you choose the best test for your client we have outlined and reviewed each test below.
The Organic Acids Test
The OAT offers a comprehensive metabolic snapshot using 74 urinary metabolites. Organic acids are the by-products of human cellular activity, the digestion of foods and the metabolism of gastrointestinal flora. The OAT is the most comprehensive profile of its kind. It evaluates yeast and bacterial overgrowth, vitamin and antioxidant levels, fatty acid metabolism, neurotransmitter levels, oxalates, mitochondrial function, oxidative stress, detoxification and much more.
The OAT is easy to collect (from a first morning urine sample) and provides information on the balance of the bacteria/yeast in the body rather than being specific to the small or large intestine. After all our bodies are made up of multiple microbiomes! This is a great entry level test that provides a biochemical overview of the body’s interconnected systems and clinical guidance or sign-posting, and for that reason should be chosen when it’s not a ‘simple’ clear-cut GI case. You might want to consider the OATs in those with fatigue, detox issues, inflammatory complaints and mood disorders. However, bear in mind, it does not provide culture-based sensitivities for bacteria/yeaset, nor screening for parasites, secretory IgA, short chain fatty acids, inflammation and digestive capacity. Therefore, it may not be the first line choice for inflammatory bowel diseases, IBS or extensive GI dysfunction.
Small Intestine Bacterial Overgrowth Test
The SIBO breath test measures hydrogen and methane gases produced by bacteria in the small intestine that has diffused in the blood, then lungs, for expiration. SIBO is characterised by an increase in the number, or a change in the type, of bacteria found in the small intestine. The detection of hydrogen and methane in the breath after ingesting a substrate (lactulose or glucose) can help determine if SIBO is the cause of gastrointestinal symptoms such as diarrhoea, constipation, bloating, cramping, nausea, reflux, flatulence and belching. Such symptoms, often non-specific and indistinguishable from those seen in irritable bowel syndrome (IBS) and other functional digestive disorders, can be the result of bacterial fermentation of short chain carbohydrates in the small intestine. Risk factors for SIBO include achlorhydria, use of proton pump inhibitors (PPIs), pancreatitis, diabetic neuropathy, migrating motor complex (MMC) impairment, gastroenteritis, motility disorders, Crohn's Disease, IBS and Coeliac Disease.
This simple test is non-invasive, performed at home and requires a 1 to 2 day preparatory diet and a 12-hours fasting period. It is widely used, medically recognised and inexpensive but like other tests has its limitations. For instance, it does not provide culture-based sensitivities, it is non-specific for strains of bacteria, it is particular to methane and hydrogen and it does not show any digestive, inflammatory or immune markers. Although SIBO testing is under discussion, it is currently the best option we have for accessing a very inaccessible area of the body.
The Comprehensive Stool Analysis
The CSA is a comprehensive examination of the gastrointestinal tract. It evaluates the status of beneficial bacteria, imbalanced commensal bacteria, pathogenic bacteria, yeasts and parasites (optional). If pathogenic cultures are identified, a sensitivity panel is provided to facilitate the selection of pharmaceutical or natural treatment agents. The efficiency of digestion and absorption is measured via faecal elastase, fat, carbohydrate, muscle and vegetable fibres, whilst the biomarkers of calprotectin, lysozyme, lactoferrin, white blood cells and mucous can be used to assess inflammation. This can help to differentiate inflammation associated with inflammatory bowel disease (IBD) from that noted in irritable bowel syndrome (IBS). Humoral immune status of the gut is measured by secretory IgA (sIgA) while the assessment of short chain fatty acids reflects overall gut health and microbiome balance. This profile is indicated for gastrointestinal symptoms, autoimmune disease, joint pain, IBD, IBS, inflammation, food sensitivities, nutritional deficiencies and skin conditions.
The CSA allows the clinician to cast a wide diagnostic net, especially when it comes to complicated cases. Cultured testing offers the potential for identifying a huge number of bacteria & yeast by MALDITOF technology, and parasites by microscopy. It is an important first line screening tool and can help structure dietary, lifestyle and supplemental interventions.
Although GI health is of paramount importance, there is no one size fits all diagnostic test. Each test has unique benefits and limitations, so it is important to be aware of these in order to make the best clinical call for your patient. Choosing the right test is dictated by your clinical observations, detailed case history and presenting signs and symptoms. Be a digestive detective, apply your clinical knowledge and get to know your patient. What are their symptoms trying to tell you and which test has the best fit?