Microbes have existed on this planet long before mammals evolved. Over millions of years of co-evolution, these microbes adapted to the conditions inside of different mammals, especially their gastrointestinal tracts. In humans, microbes colonize our gastrointestinal tract during birth, remaining with us for our lifetimes. The community, composed of trillions of microbial cells, is called our microbiome.
In recent years, researchers found links between our gut microbiomes and our metabolism, immune system, physiology and even our brain. It is abundantly clear these this community impacts our health. A recent study even finds some molecules derived from our guts associate with quality-of-life and depression.
Several studies indicate that different microbes in the gut could impact the efficacy of cancer therapeutics. Other studies find clear benefits in targetting the microbiome for C. difficile infection. Supplements with live beneficial bacteria called probiotics improve outcomes in this one specific condition.
However, we run into a problem where we have more data than we can interpret into actionable insights. We do not fully understand the cause-and-effect for many of these interactions. If we see that people with an anxiety disorder have a different microbiome than those without, is it a driving factor of anxiety? Is it due to differences in diet? The chicken and the egg problem confounds our ability to answer these questions.
Several direct-to-consumer kits offer you the opportunity to understand your unique gut microbiome. The eventual goal is helping us determine which foods contribute to a healthy gut and a healthy brain. In contrast to genome testing like 23AndMe, the readouts on a gut microbiome test do change. Factors such as diet, time, stress and infections could rapidly remodel parts of this community. Microbiome testing hopes to empower consumers to reshape their microbiome to improve their health.
Accordingly, many of these companies (Thryve, BIOHM, Atlas) also offer predictions and suggestions for your digestive health, diet and mental health. Some offer ongoing subscriptions to monitor your gut health over time, along with personalized supplements.
What’s the verdict on these at-home gut tests?
Direct-To-Consumer Gut Health Tests
How do they work?
The bacteria in our microbiome live on a mucus layer on top of our gut cells. Bacteria differ along our gut because they have different preferences for oxygen and acidity. Since these microbes are on the mucus layer, they also slough off and end up in our poop. The majority of these microbes, however, come from our colon. In many of these tests, this is our microbiome sample!
You, the consumer, preserve the sample in a solution that aims to keep the community stable as it travels by mail. One of the hangups I have with gut tests is this step. Often they lack transparency in their testing of this solution. Additionally, instructions must make it clear and easy to collect this sample without contamination. While I understand it’s necessary to send these samples by mail, consumers often aren’t aware that this process influences the results that they might receive.
In laboratory/university/hospital settings, samples are frozen, preventing any growth or change of the bacterial community. After all, the microbes preferentially live inside of a gut! Other conditions rapidly remodel and change this composition, making it a less reliable indicator for the gut microbiome. Many of these direct-to-consumer companies do not provide research and comparisons into how their solution, compared to freezing, changes this composition.
To quantify what microbes are present in the sample, researchers in a laboratory break up the cells to collect their genetic material. A gene found across all bacteria, with subtle variations between different species, called the 16S rRNA gene, is amplified and sequenced. Bioinformaticians then determine what exactly was in this sample and make some predictions. More expensive approaches can identify all of the genes in your sample including those belonging to fungi and viruses!
How reliable are predictions from gut testing companies?
Many of these companies should strive to make their consumer’s data easily understandable. They have to toe the line between elegant layperson descriptions and confabulations. Companies must be honest about what they aren’t able to do.
- Scientists still have no idea whether a microbiome is healthy or not. We can count the different microbes that are there. We can predict what their metabolic activities might be. But we cannot tell whether a microbiome is healthy or not. It’s like determining the health of an entire forest ecosystem from one snapshot.
- Everything from diet, genetics, time of day, stress, sample collection or bioinformatics analysis could influence your result. If you send the same sample to two different companies, you get two different interpretations.
- There is no evidence that supplements sold by these companies change our microbiome, alleviate anxiety or improve bloating.
- Companies don’t transparently explain their methods or confidence in their results.
- Sequencing the 16S gene might tell you which bacteria are there, but it won’t tell you about their metabolic functions.
- The fecal microbiome is still different from the intestinal microbiome! It also does not tell us about other regions of the gut, where the microbiome plays physiological roles. Addressing this, scientists recently published research in ACS Nano in September 2020, describing a capsule that functions as an ingestible laboratory. It collects samples throughout the gastrointestinal tract for scientists to have a more representative idea. Perhaps in the future, these tests could tell us about the geographical organization of our microbiome.
When a company offers broad prediction and advice, without adequately backing up or explaining these claims, they mislead their customers.
It’s frustrating because the life inside of our guts is fascinating as it is. Without any other gimmicks, these companies would be harmless. The declining cost of sequencing has seen a rise in Silicon Valley startups over-hyping their science. It makes people less excited about real innovation in the field.
In contrast to these companies and their broad claims, Day Two provides clinical evidence for their product. They provide insights to consumers with diabetes that are backed by evidence and clinical trials. DayTwo shows that these products provide benefits when developed with clinical trials.
Founder and CEO Lihi Segal describes her venture:
DayTwo is not a curiosity based thing, it’s not that we profile your gut microbiome and tell you some cool things around it. We have an actionable outcome that helps you better manage your post-meal sugar spikes.
We have many pieces of the microbiome puzzle but we don’t know how exactly they come together to predict or influence our health. Despite this uncertainty, the market value for microbiome supplements will reach over USD 70 billion by 2025! With the decreasing cost of microbiome sequencing-technology, sequencing and supplement ventures will proliferate. Many companies also offer services for ongoing monitoring of the microbiome as well as dietary recommendations.
The promise of personalized medicine and health is alluring! The microbiome sounds like the next, great frontier for medicine.
Another important note is that we already know what kind of foods are generally healthy. The Mediterranean diet, high in vegetables, fruits, seeds and fish, provide us and our microbiome many general benefits. While this is certain, there are still ongoing studies to understand how our microbiome individually responds to food. Its unclear if we can identify foods to specifically modify the microbiome. It’s still unclear whether changing the composition even improves health outcomes.
As with other forms of genetic testing, there are privacy issues. Over time, the unique features of the microbiome might sufficiently identify an individual. Additionally, this product might provide hope or worries to vulnerable individuals navigating their health. More ethical considerations, as well as scientific studies are needed to address the rise in microbiome sequencing companies.