Let’s say you mail your poop to two different companies—not an illegal act, by the way, provided it doesn’t smell or soil anything, and that it’s . It also helps if the two companies receiving your number two asked for it. In this scenario, they have offered to test your sample for the bacteria it contains, in a bid to give you a better picture of your gut health and how to improve it.
What if I told you that the results you would get from these two companies are comparable to what you would get if you sent your sample to company #1 and your friend sent theirs to company #2? Would this bit of modern-day backside astrology be worth the price tag?
Yet, this is what , whose results were just published, has shown. Seven different companies; a standardized poop sample; and results that are all over the place.
But wait, I hear you say: a standardized poop sample? I think that reporters who jumped on this story missed the forest for the trees. How »ĺ´ÇĚýyou standardize a stool sample and what does it mean to be a “healthy donor” in this context?
If one lab could do it, it had to be the institute that sells freeze-dried urine and two-gram samples of urban dust, the place that when you order “sludge” asks you to specify if you want the domestic or industrial kind.
A gold standard for brown
For a mere US$ 1,027, you too can own human fecal material. You may wonder why pay through the nose for it when we all produce our own for free. That’s because łŮłóľ±˛őĚýmaterial, referred to as , has been carefully curated by the virtuosi of standardization: the scientists of .
The National Institute of Standards and Technology, founded in 1901, is the national measurement institute of the United States. Science is all about measurements: grams, metres, degrees Celsius. NIST creates and maintains the standards, so that people who make precision instruments can get them calibrated properly, for example. They don’t just own these standards; they also sell many of them, including RM 8048.
If you’re trying to find out whose poop you’ll be buying for a grand, I’m afraid it’s all very hush-hush. NIST has no identifiable private information on who produced the material they are selling you. But what you will get are four vials each of two types: omnivore stool—from people who eat just about anything, including meat—and vegetarian stool. If you’ve ever wanted to know the exact chemical composition of what comes out the other end after a good meal, NIST has you covered. Tables 4 and 5 in  list every single molecule found in RM 8048, including 1,3,7-trimethyluric acid and 5-hydroxyindole-3-acetic acid. The omnivore sample comes from five donors who together contributed 1.2 kilogram of starting material, which was mixed together into a slurry. Every contributor had to self-report as healthy; had to stay away from antibiotics for three months prior to donating, as antibiotics wreak havoc on the gut microbiome; had to keep a food diary; and were screened for infectious diseases like syphilis and hepatitis B and C.
These vials are stored at -80 degrees Celsius (-112 degrees Fahrenheit)—a standard temperature for long-term storage of biological material—and can be shipped to anyone who desires them. Reproducibility being key in research, making this standardized slurry available to microbiome scientists is important. But when this new study testing seven different gut microbiome kits was being done, NIST did not have RM 8048. “It took several years to develop and included different pilot versions,” wrote Dr. Stephanie Servetas when I asked her over email. She’s the lead author on this new paper and a microbiologist working at NIST. Instead, they used a sample from an individual donor from The BioCollective.
Founded in  to accelerate research into the many microorganisms that populate our body, The BioCollective is another example, after RM 8048, of how research can catalyze the development of truly fringe products. Ask yourself this: how are you supposed to collect your own stool and send it in? The BioCollective designed  that uses suction cups to float halfway between your buttocks and the toilet bowl, a sort of hammock for your backside babies. Armed with this vessel—which kind of looks like a repurposed Chinese takeout container with a taste for aeronautics—they built a fecal sample bank. One of these samples was used by NIST to test how reliable these direct-to-consumer microbiome health kits really were.
The results were so varied that they might as well have come from playing a game of craps.
The illusion of knowledge
The microbiome is hot right now. The study of the microorganisms that exist in our gut and on our skin has yielded promising, early results about their role in our health, but promises can’t easily be monetized. This is why some business-minded folks are selling you tomorrow’s science today. The model is based on direct-to-consumer (DTC) kits like 23andMe, except the biological sample you send in doesn’t come from your mouth. Company scientists analyze it, send you a detailed report (e.g. the abundance of families of bacteria like Bifidobacterium and Faecalibacterium), and give you advice on how to improve your health… which usually includes subscribing to a dietary supplement that they sell. In the world of hype, don’t be surprised if the same business sells you both the problem and the solution.
Prior to the study by NIST, individuals had tested out gut microbiome kits from different companies and reported on their disparities. One  complained that the health advice he was sold, after spending US$ 130 on a kit, was something you could get from a government website: exercise more and eat more fruits and veggies. Another, who  a decade ago at the beginning of this trend, said that knowing the Latin names of all the bacteria in her poop was fascinating but also frustrating: why are they there and what do they do? Companies now provide more details but are those even accurate?
NIST, in collaboration with a couple of collaborators, sent in their “human fecal standard” to seven different companies that the authors found after doing a web search. The companies are not named in the paper, which is standard practice in this kind of research to avoid lawsuits. A NIST employee created accounts using a personal email address, so that the companies wouldn’t be tipped off that they might be on the receiving end of a test. Three kits were ordered from each company, to see how consistent their results were.
The overall picture points to companies that, in my opinion, have no idea what they are doing because our knowledge of the gut microbiome is not deep enough or specific enough. One company—which, again, did not realize it had received three kits containing the exact same poop sample—deemed that one of them had below average gut health while the other two’s gut health was characterized as above average. This is an extreme example of the many discrepancies the authors noticed both within and between companies. All seven companies tested for C. difficile, a bacterium often acquired in hospital and which makes us ill: three companies said they found it in the sample, while the other four said it wasn’t there.
The reason the results were all over the place is that choices need to be made at each step of the process, choices that will impact the final results. Exactly how do you collect your poop? What buffering solution does the company give you to put it in? How long do you wait before you mail it? Which technique does the company’s scientists use to extract the bacteria’s genetic material from the sample? What sequencing technology is used? How do they analyze the reams of results? Changes in any of these will alter what gets found and reported.
And the book isn’t closed on defining what a “healthy microbiome” is. A healthy skin, for example, is not just one thing. Likewise, a healthy gut microbiome is likely to be a range, not a unique ideal.
The road to standardization
How do we move forward from this primitive, borderline predatory direct-to-consumer pseudoscience? Much like how NIST spent years standardizing its number twos, we need more standardization in microbiome research and clinical products. Recently, an  was published on this very topic. Sixty-nine microbiome experts from 18 countries participated in multiple rounds of online consensus building to arrive at a list of guiding principles to move the discipline forward.
One of their statements is that people shouldn’t change their medication based on a gut microbiome test kit until they speak to their physician, and that we shouldn’t request this kind of testing without a recommendation from a genuine healthcare professional. The above experts agreed that “personal trainers, coaches, homeopaths, and osteopaths are discouraged to prescribe any microbiome testing.” To be blunt, they do not understand it and are likely to give erroneous health advice based on these preliminary findings, e.g. recommending expensive and poorly regulated dietary supplements that are unlikely to help.
Even for people suffering from gastrointestinal disorders, the panel concluded that there is no direct evidence that these kinds of kits help a doctor manage these patients.
Right now, these DTC gut microbiome kits are just an expensive way to discharge your wallet, receive Latinate predictions, and get courted to buy supplements that likely won’t help you.
In essence, you are flushing money down the toilet.
Take-home message:
- Gut microbiome kits you can order online promise to analyze your stool sample and tell you how healthy your gut is and how to improve it.
- A recent study tested seven companies offering these kits with samples from the same stool, and results were significantly different, even for multiple samples sent to the same company.
- Our understanding of the gut microbiome is too preliminary right now for these kits to be useful, and the entire process of collecting stool and analyzing it needs to be standardized before these kits can be anything other than a waste of money.
