In 1904, in a talk at the Pasteur Institute in Paris, Elie Metchnikoff, one of the fathers of modern immunology, put forward his idea that aging was caused by harmful bacteria that live in our intestines. To delay it, he recommended eating yogurt, a food with beneficial bacteria widely consumed in a region of Bulgaria known for the longevity of its inhabitants. Although he later tried to clarify the miraculous properties of yogurt, the news written by a journalist at the conference caused a boom in the consumption of the product, seen as an anti-aging elixir.
Since then, what is known regarding the microbes inside us has multiplied and their relevance to human health is becoming increasingly clear, but this knowledge still raises excessive expectations. Scientists acknowledge that little is still known regarding how to apply that knowledge to improve human health. However, there are a large number of companies that sell tests to understand the microbiome aimed at people with all types of ailments.
The company Synlab, for example, recommends its myBiome test to people with digestive disorders, cardiovascular diseases or chronic fatigue. The test, which is carried out from a stool sample, is sold for 313 euros through its website. The Quirón group offers two types of intestinal microbiota test, a simple one, for 290 euros, and a complete one, for 490, for patients with gastrointestinal pathologies, including colon cancer. On its page it is specified that a medical prescription is not necessary. Neither Synlab nor Quirón wanted to speak to this newspaper for this article.
In an article published by the magazine Science, several legal and medical experts say the direct-to-consumer microbiome testing industry needs more regulation. Referring to the US market, they write: “Companies’ claims that they are able to detect abnormal microbiomes are not supported by research. The tests lack analytical and clinical validity and require [más supervisión gubernamental] to prevent harm to consumers,” they conclude.
Sequencing techniques used to analyze samples, typically mailed feces, identify the microorganisms present, their relative abundance, and, in some cases, the metabolic functions of those microbes. After a few weeks, a time that varies depending on companies, you receive a report describing the state of the microbiome, which is placed on the healthy or sick spectrum. This verdict, as explained by the authors of the article Science, is based on the comparison of the user’s microbiome with that of other healthy subjects or those suffering from some ailments. The limited composition of the companies’ databases makes the data non-representative and the comparisons unhelpful.
“Products are launched that analyze the microbiota in search of dysbiosis [un desequilibrio el ecosistema microbiano de los pacientes] with the very big defect that there is no universally validated technology,” says Francisco Guarner, digestologist and member of the scientific committee of the International Human Microbiome Consortium. “There are many technologies in place, some better than others, but the most important thing is that there are no clear markers that can be associated with a clinical decision. Doctors do not usually order these tests, neither in the public nor in the private system, they are requested more by dieticians or people from alternative medicine, but the business is aimed at the consumer,” he explains. “As no one knows how to interpret the final product and there is no validation of the meaning of the markers, reports are created to justify what they charge, 20 or 30 pages long, which the patient often reads in horror and which, sometimes, takes to the doctor, who doesn’t know what to say,” concludes Guarner.
The team led by Diane Hoffmann, from the University of Maryland (USA), points out that “approximately 45% of the companies identified sell supplements that the companies recommend to consumers based on their results. In addition, these companies encourage repeat tests to determine if these supplements or changes in diet have modified the clients’ microbiome,” she added.
The lack of analytical validity was observed when, with the same sample, different laboratories offered different results, something that also happened when the same sample was sent to the same laboratory. The authors believe that these inconsistencies may be due to defects in sample collection, shipping and preservation, differences in the software or databases used as references, or the technologies used in the analyses. Furthermore, even with systems that allow valid analysis, there is no consensus on what it means to have a healthy microbiota.
“There is a range of different microbiotas that can be healthy and there is enormous heterogeneity between individuals. Each person has a different story and that means that each one has a different microbiota,” explains Fermín Milagro, director of the precision nutrition line at the Nutrition Research Center of the University of Navarra. In his opinion, the data from the tests might be useful “to see an enormous dysbiosis, if there are three species that dominate a lot or, if the prices were cheaper, to see if with a treatment I am varying a parameter that interests me.” “But they’re not going to allow you to predict your risk of Alzheimer’s in the next decade,” he adds. “I think that, in short, the tests can have very interesting applications, but with an interpretation by trained professionals, not sending the client a report that they will not understand,” he says.
The use of microbiome analyses, with well-defined objectives and interpreted by professionals, is also defended by the researcher at the National Cancer Research Center (CNIO) Nuria Malats. She published a study in which she managed to associate a combination of 17 intestinal microorganisms with the risk of suffering from pancreatic cancer. This system is proposed as a method to detect pancreatic cancer before it is too late to treat it, but it will still require a lot of work to validate its clinical usefulness and be able to use it as an early diagnosis method. Malats agrees with the thesis of Hoffman and her colleagues regarding tests that are sold directly to consumers. “It’s too premature,” she says. “This is like genetic tests, which tell you that you have a gene, but what does that mean? This is even more complex, because genetic tests do not change throughout life, but the microbiome is very dynamic,” she points out.
Experts agree on the need for better regulation. Now, neither the European Medicines Agency nor its American counterpart, the FDA, control these products. “Although many companies make it clear that their tests are not diagnostic, many marketing claims imply, and may lead consumers to believe, that the results are based on scientific accuracy and are medically relevant, when this is not true.” has been substantiated”, assert the authors of the article. Among the risks of this unreliable information, which in many cases is used by people who have been on a pilgrimage for years in search of solutions to their health problems, there is an erroneous self-diagnosis or the replacement of supplements with medications prescribed by professionals. “It’s a waste of money,” Guarner summarizes.
