Gastrointestinal testing for athletes: GI- MAP or GI Effects? - by Mémé Watanabe

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For conventional sports nutrition practitioners, optimal performance is about specific calculations to provide adequate macronutrients for their client. For the functional sports nutrition practitioner, digestion of food and absorption of nutrients also comes into play, and how these nutrients support important biochemical pathways during strenuous exercise. Nutrient absorption occurs mainly in the small and large intestine, so it goes without saying that the integrity of the gut is essential for micronutrient absorption and better performance.

There are a number of environmental, genetic, dietary and lifestyle factors that can reduce the integrity of the gut, and one consistent factor seen in clinical scenarios is stress.

Stress is the body’s natural process for dealing with challenging situations, but should only really be for a short period of time. All body systems that are not needed for survival, such as the digestive and detoxification systems, are slowed down in order for the body to mobilise as much of its resources to the sympathetic nervous system (SNS). A persistent activation of the hypothalamic-pituitary-adrenal (HPA) axis may prolong the reduced function of the body’s digestive system. This, in turn, may cause food to remain undigested in the gut, leading to increased fermentation, proliferation of symbiotic bacteria, that can result in increased inflammation, and possibly intestinal permeability.

If a client comes into your clinic presenting with gastrointestinal issues, such as bloating and irregular bowel movements, and you suspect compromised digestion, dysbiosis, or intestinal permeability, you might consider a stool test.

Until recently, stool testing for dysbiosis was carried out using cultured samples in a laboratory. Polymerase Chain Reaction (PCR) testing has now taken over from the traditional culture testing for gut bacteria and yeast. Since most of the gut bacteria and some parasites are anaerobic, culturing them outside the body becomes difficult and therefore, harder to detect bacterial infection. PCR testing has been around since the 1980s, but has only been readily available for functional testing in the last few years. Since it enables laboratories to look at the DNA of bacteria, testing with this method has become more sensitive with higher detection rates.

Both Invivo Clinic and Genova Diagnostics carry out PCR stool testing to assess gut microbiome.

Invivo Clinic offers a comprehensive stool test called the GI-MAP, which assesses just under 50 pathogenic, normal, opportunistic and autoimmune disease-related bacteria, yeast and parasites. Their standard one-stool sample test includes H.pylori, elastase, secretory immunoglobulin A (sIgA), calprotectin and gliadin. GI-MAP includes zonulin testing, a protein that regulates the tight junctions between cells in the small intestine and is a biomarker for intestinal permeability or gut integrity. However, this is just one marker to assess gut integrity and there are other tests available at other laboratories such the PEG urine test.

Genova Diagnostics’ GI Effects also assesses a similar number of microbes, including bacteria, yeast and parasites, with either one- or three-day samples. There are markers you can add on to the testing like Campylobacter, Clostridium, Escherichia coli, Heliobacter pylori, zonulin, four of which (excluding the Clostridium) are included in the GI-MAP test. While GI-MAP includes sIgA and calprotectin for assessing gut inflammation, GI Effects includes these plus eosinophils as a marker of inflammation. It also includes short-chain fatty acids (SCFAs) and markers to assess fat maldigestion, such as cholesterol, triglycerides and phospholipids. These and other digestive markers such as pancreatic elastase, which is also assessed in the GI-MAP test, may indicate digestive issues that could reduce the absorption and use of valuable nutrients for health and optimal performance. Additionally, GI Effects shows a section on bacteria and yeast sensitivity to natural supplements or prescription drugs, which GI-MAP does not.

I have used both tests and it really depends on what markers are important to assess your client’s needs. Some important considerations include cost, variety of markers and the simplicity of the test. Also, some of the parasites or bacteria tested are different in each test. For example, GI-MAP tests for Cyclospora parasite, which is linked to traveller’s diarrhoea. You may want to test this if you know your client has travelled to countries that could increase the risk of Cyclospora infection. However, it doesn’t test for Oxalobacter, which is a gram-negative bacteria that metabolises oxalates and may reduce the risk of kidney stones. As there are many different advantages for each test, I recommend studying both tests and seeing which markers are more convenient to assist you with giving recommendations for each individual client.