By Carol A. Kemper, MD, FACP

Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center

Dr. Kemper reports no financial relationships relevant to this field of study.

SOURCES: Saey TH. Here’s the poop on getting your gut microbiome analyzed. Science News, June 17, 2014.
Rabin RC. Can I test the health of my gut microbiota? The New York Times, July 7, 2017.

Google “gut microbiota testing” and see the array of possible “gut report” kits out there for purchase. Send in a sample and pay a fee — usually $100 or more — and you will receive a profile of your gut microbiome, with lots of detailed information and colorful graphics on the dominant species populating your gut. Your fecal microbiota will be compared to the “normal” profiles of other Americans or people in other parts of the world, vegetarians, or those who follow different diets. The problem is that little is known about the typical genomic profile of the gut or what is “normal.” There’s obviously tremendous diversity, even in healthy people. Researchers have determined that persons with diabetes or inflammatory bowel disease — or people who have received recent antibacterial therapy — may exhibit very different microbiota profiles. Unfortunately, no one really knows what these differences mean in terms of your overall health.

Different methodologies also may offer differing results. Saey submitted stool samples to two companies for testing and received wildly different results.

Increasingly, we see outfits that offer molecular testing of blood, stool, or other specimens, but with little credibility or science behind it. Yet, patients looking for an explanation for their symptoms or an illness will latch on to anything. A young Stanford graduate student who felt “fuzzy-headed” for more than a year recently spent $1,000 on specialized “molecular” testing of his blood and stool, only to be disappointed when I explained the results were basically uninterpretable.