April 24, 2024 – Companies that sell colon cancer Microbiome Direct-to-consumer tests offer quite a lot of claims to advertise their products, but experts doubt whether or not they can actually back up these claims.
“We analyze the trillions of microbes in your gut flora and develop a unique formula for your individual gut needs,” says one company. “Based on your results, receive actionable diet, supplements and lifestyle recommendations from our microbiome experts, tailored to mom and baby's biomarkers. … Family members like fathers or siblings are also welcome,” says one other.
The firms claim they will improve gut health by offering patients personalized treatments based on the outcomes of their gut microbiome testing. The problem is that no vendor, company or technology can reliably do that yet.
Clinical implications, no applications
The microbiome is the “Constellation of microorganisms that inhabit the human body,” including many strains of bacteria, fungi and viruses. This constellation includes some 39 trillion cells.
Although knowledge about the oral, skin and vaginal microbiome is increasing, the gut microbiome is probably the most studiedHowever, while research increasingly shows that the gut microbiome Clinical implicationsMuch remains to be done before reliable applications based on this research are available.
But the lack of scientific evidence and validity has not stopped a growing number of companies around the world from offering microbiome tests directly to consumers, says Erik C. von Rosenvinge, MD, professor at the University of Maryland School of Medicine and chief of gastroenterology at the VA Maryland Health Care System in Baltimore.
“When you go to their websites, these companies at least give the impression that they are providing actionable, useful information, even if it is not explicitly stated,” he said. “The websites recommend microbiome testing and often also recommend supplements, probiotics or other products they sell. And consumers are told that once they start taking any of these products, they need to get retested to see if they are getting any benefit from it.”
Von Rosenvinge and colleagues wrote a Current article In Science arguing that direct-to-consumer microbiome tests “lack analytical and clinical validity” – and yet industry regulation has been “generally ignored”. They identified 31 companies worldwide, 17 of that are based within the US, and claim to supply products and/or services geared toward altering the gut microbiome.
Unreliable, unregulated
The lack of reliability was confirmed by experts who reviewed the tests.
“Some have taken the identical stool sample, sent it to several firms and received different results,” said von Rosenvinge. “Some have also taken a stool sample and sent it to the identical company under two different names and received two different results. If the test is unreliable at its basic level, it's difficult to make use of it clinically.”
The methods used by test subjects and the procedures used by companies can influence the results, said Dr. Dina Kao, a professor at the University of Alberta in Edmonton, Canada.
“There are so many biases that may occur at each step, ranging from how the stool sample was collected and the way it's preserved or not, because that may introduce loads of noise that might alter the analyses. What primer they use to amplify the signals and what bioinformatics pipeline they use can be vital,” Kao said.
Different researchers and companies use different technologies, so it's very difficult to compare them and create a standard, says Mahmoud Ghannoum, PhD, professor in the departments of dermatology and pathology 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 standardizing the test more difficult than if only one organism were involved, Ghannoum said.
“Although many researchers concentrate on bacteria, there are also fungi and viruses. We need standardization of testing methods for these organisms if we wish to have regulations,” said Ghannoum, co-founder of BIOHMa microbiome company that offers non-diagnostic testing and sells a variety of probiotics, prebiotics and immunity supplements. BIOHM is one of the 31 companies identified by Rosenvinge and colleagues.
Possible pitfalls
Whether test results are marketed by commercial companies as wellness aids or diagnostic tools, providing advice based on the results “is an actual risk,” Kao said. “We still don't know a lot about which microbial signatures are related to which diseases.”
“Even if we have now an answer, just like the Crohn's disease elimination food regimen, a health care provider doesn't know the intricacies well enough to present advice to a patient,” she said. “That really ought to be done under the guidance of a nutritionist. And if an organization is selling probiotics, I personally think that's unethical. I'm pretty sure there's all the time going to be some sort of conflict of interest.”
Dietary supplements and probiotics are generally safe, but can have negative effects, noted von Rosenvinge.
“Occasionally we get individuals who have liver problems due to certain supplements. In rare cases, probiotics have also been linked to infections attributable to these organisms, often in individuals with weakened immune systems,” he said.
Other risks include people taking supplements or probiotics when they actually have a medically treatable condition, or being late in diagnosing a potentially serious underlying condition such as colon cancer, he said. Some patients stop taking their conventional medications and take supplements instead, or there may be interactions between the medications and supplements when taking both.
What you should tell patients
“Doctors should discourage their patients from doing these tests,” said gastroenterologist Colleen R. Kelly of Brigham and Women's Hospital in Boston. “I explain to patients that these tests aren't validated, provide clinically meaningless data and aren't definitely worth the money. There is a reason they aren't covered by insurance.”
“Recommendations to purchase probiotics or supplements manufactured by the testing company to 'restore a balanced or healthy microbiome' clearly seem to be scams,” she said. “I consider a few of these firms are benefiting from patients who're desperately searching for answers to elucidate chronic symptoms like bloating in irritable bowel syndrome.”
Von Rosenvinge said the message to patients is “that science just isn't yet able to make meaningful use of the outcomes of those tests. We consider that the microbiome may be very vital for health and disease, however the tests themselves, of their current state, aren't as reliable and reproducible as we would really like.”
When patients come in with test results, the first thing a doctor should ask is what prompted them to seek such information in the first place, von Rosenvinge said.
“Our Patient focus groups suggested that many haven't received clear, satisfactory answers from traditional medicine,” he said. “We don't have a single test that claims yes, you will have irritable bowel syndrome, or no, you don't. We could suggest things which might be helpful for some people and fewer so for others.”
Kelly expressed concern that “there are quacks and scammers on the market who're joyful to take your money. They could also be smart people who find themselves capable of do very high-level testing and even provide very detailed and accurate results, but that doesn't mean we all know what to do with them.”
She hopes that there shall be a microbiome-based diagnostic test in the long run, especially if it is feasible to control the gut microbiome in various diseases.