Companies selling gut microbiome tests directly to consumers offer up a variety of claims to promote their products.
“We analyze the trillions of microbes in your gut microflora and craft a unique formula for your unique gut needs,” one says. “Get actionable dietary, supplement, and lifestyle recommendations from our microbiome experts based on your results, tailored to mom and baby’s biomarkers. ... Any family member like dads or siblings are welcome too,” says another.
The companies assert that they can improve gut health by offering individuals personalized treatments based on their gut microbiome test results. The trouble is, no provider, company, or technology can reliably do that yet.
Clinical Implications, Not Applications
The microbiome is the “constellation of microorganisms that call the human body home,” including many strains of bacteria, fungi, and viruses. That constellation comprises some 39 trillion cells.
Although knowledge is increasing on the oral, cutaneous, and vaginal microbiomes, the gut microbiome is arguably the most studied. However, while research is increasingly demonstrating that the gut microbiome has clinical implications, much work needs to be done before reliable applications based on that research are available.
But , Erik C. von Rosenvinge, MD, AGAF, a professor at the University of Maryland School of Medicine and chief of gastroenterology at the VA Maryland Health Care System, Baltimore, said in an interview.
“If you go to their websites, even if it’s not stated overtly, these companies at least give the impression that they’re providing actionable, useful information,” he said. “The sites recommend microbiome testing, and often supplements, probiotics, or other products that they sell. And consumers are told they need to be tested again once they start taking any of these products to see if they’re receiving any benefit.”
Dr. von Rosenvinge and colleagues authored a recent article in Science arguing that DTC microbiome tests “lack analytical and clinical validity” — and yet regulation of the industry has been “generally ignored.” They identified 31 companies globally, 17 of which are based in the United States, claiming to have products and/or services aimed at changing the intestinal microbiome.
Unreliable, Unregulated
The lack of reliability has been shown by experts who have tested the tests.
“People have taken the same stool sample, sent it to multiple companies, and gotten different results back,” Dr. von Rosenvinge said. “People also have taken a stool sample and sent it to the same company under two different names and received two different results. If the test is unreliable at its foundational level, it’s hard to use it in any clinical way.”
Test users’ methods and the companies’ procedures can affect the results, Dina Kao, MD, a professor at the University of Alberta, Edmonton, Alberta, Canada, said in an interview.
“So many biases can be introduced at every single step of the way, starting from how the stool sample was collected and how it’s preserved or not being preserved, because that can introduce a lot of noise that would change the analyses. Which primer they’re using to amplify the signals and which bioinformatic pipeline they use are also important,” said Dr. Kao, who presented at the recent Gut Microbiota for Health World Summit, organized by the American Gastroenterological Association (AGA) and the European Society of Neurogastroenterology and Motility (ESNM).
Different investigators and companies use different technologies, so it’s very difficult to compare them and to create a standard, said Mahmoud Ghannoum, PhD, a professor in the dermatology and pathology departments at Case Western Reserve University School of Medicine and director of the Center for Medical Mycology at University Hospitals in Cleveland.
The complexity of the gut microbiome makes test standardization more difficult than it is when just one organism is involved, Dr. Ghannoum, who chaired the antifungal subcommittee at the Clinical and Laboratory Standards Institute, said in an interview.
“Even though many researchers are focusing on bacteria, we also have fungi and viruses. We need standardization of methods for testing these organisms if we want to have regulations,” said Dr. Ghannoum, a cofounder of BIOHM, a microbiome company that offers nondiagnostic tests and markets a variety of probiotics, prebiotics, and immunity supplements. BIOHM is one of the 31 companies identified by Dr. von Rosenvinge and colleagues, as noted above.
Dr. Ghannoum believes that taking a systematic approach could facilitate standardization and, ultimately, regulation of the DTC microbiome testing products. He and his colleagues described such an approach by outlining the stages for designing probiotics capable of modulating the microbiome in chronic diseases, using Crohn’s disease as a model. Their strategy involved the following steps:
- Using primary microbiome data to identify, by abundance, the microorganisms underlying dysbiosis.
- Gaining insight into the interactions among the identified pathogens.
- Conducting a correlation analysis to identify potential lead probiotic strains that antagonize these pathogens and discovering metabolites that can interrupt their interactions.
- Creating a prototype formulation for testing.
- Validating the efficacy of the candidate formulation via preclinical in vitro and in vivo testing.
- Conducting clinical testing.
Dr. Ghannoum recommends that companies use a similar process “to provide evidence that what they are doing will be helpful, not only for them but also for the reputation of the whole industry.”