The science behind
DTC microbiome test kits

making your microbiome knowable

Direct-to-consumer (DTC) gut microbiome tests offer you knowledge of the microbial communities in your intestinal tract. Most companies will identify these microbes and interpret these results to provide information on if these microbes are "beneficial" or "harmful" and how diverse the species are. Some companies like Viome set themselves apart by offering consumers information on what these microbes are doing inside you.

You can order DTC gut microbiome tests online and receive a package in the mail containing a stool collection and preservation kit. Once you collect your sample, you mail it out to the company's testing facility to have it analyzed. After completing sometimes extensive questionnaires, your results can be accessed on a pleasant and colourful webpage.

But what exactly are these companies doing with your sample to get these results?

what is the science behind these tests?

Viome

Metatranscriptome Sequencing

Almost all living organisms transcribe their DNA into mRNA (messenger ribonucleic acid), which is then translated into functional proteins

All the mRNA in a stool sample (the metatranscriptome) can be sequenced

This is done by isolating the mRNA then converting it back to DNA using enzymes

Then the original DNA code of active genes is compared to a database to show the types of organisms (bacteria, fungi, viruses) present, their abundance, and to quantify the relative activity of their genes

Ombre

Atlas

16S rRNA Sequencing

Bacteria and archaea have a gene called 16S rRNA

The 16S rRNA gene is a region on bacterial DNA that when transcribed, will form 16S (a name for the size) rRNA (a type of non-informational, housekeeping RNA that does not form proteins like mRNA would)

DNA is isolated from a stool sample and sequenced for the 16S rRNA gene from different bacteria in the sample

The 16S rRNA gene is present in almost all bacteria and undergoes small changes representative of evolution – thus it is a useful site to distinguish different bacteria

This sequencing shows what type of bacteria are present in the gut microbiome and using statistical analyses, their relative abundances to get a diversity score

When these companies explain their science, one of the main themes is the proprietary nature of their processes (i.e. proprietary preservative solutions, databases...etc.).

Reminding us of their commercialization of known laboratory techniques that incorporate minor changes to improve efficiency and processing of large samples.

As most of these laboratory techniques are well-known and utilized, a significant feature of these companies' offerings is the interpretation of sequenced data through proprietary algorithms and artificial intelligence systems.

what do the results mean?

Now that you know what microbes are inside you and potentially what genes they have activated, most companies then offer personalized recommendations on diet and supplements to help you optimize your individual gut microbiome.

But what are these recommendations based on? Can changing your diet or adding supplements really change your microbiome long-term?

Knoppers et al. (2021) analyzed the websites and policy documents of 12 DTC microbiome test companies worldwide. One key area of concern they identified was the "inconsistencies in how companies present the scientific validity and medical relevance of their tests, with a focus on recommendations to repeat testing over short periods of time to track progress" (545).

Firstly, companies do not openly report the specifics of the laboratory techniques used in their tests (i.e. exactly what genetic markers are used to identify different bacterial species).

Secondly, there are few studies showing long-term changes in gut microbiome composition from specific interventions, but periodic testing as promoted by the companies suggests that “beneficial” changes can be measured in months or even weeks.

Lastly, only Atlas Biomed’s test is registered as a “medical device” in the UK; while others seem to occupy the space of “wellness/lifestyle” products while still associating themselves with science/medicine in their promotional material

References

Hatch, Andrew et al. 2019. “A Robust Metatranscriptomic Technology for Population-Scale Studies of Diet, Gut Microbiome, and Human Health.” International Journal of Genomics 2019, no. 1718741. doi:10.1155/2019/1718741

Janda, Michael J. and Sharon L. Abbott. 2007. “16S rRNA Gene Sequencing for Bacterial Identification in the Diagnostic Laboratory: Pluses, Perils, and Pitfalls.” Journal of Clinical Microbiology 45, no. 9: 2761-2764.

Knoppers, Terese et al. 2021."The omics of our lives: practices and policies of direct-to-consumer epigenetic and microbiomic testing companies," New Genetics and Society 40, no. 4: 541-569. doi: 10.1080/14636778.2021.1997576

The science behind DTC microbiome test kits