Enlarge / Laboratory technicians in France prepare stool to treat patients with serious colon infections by fecal microbiota transplantation (FMT), also known as gut flora transplant (GFT) in 2019. (credit: Getty | THIERRY ZOCCOLAN )

For the first time, the US Food and Drug Administration has granted approval for a feces-based microbial treatment, which is used to prevent a recurring diarrheal infection that can become life-threatening.

The approval, announced Wednesday, is years in the making. Researchers have strained to harness the protective qualities of the complex, diverse, yet variable microbial communities found in healthy people's intestines and stool. Early on, rich fecal matter proved useful for restoring balance and blocking infection in those whose microbiomes have been disturbed—a state called dysbiosis, which can occur from disease and/or use of antibiotic drugs. But, our understanding of what makes a microbiome healthy, functional, and protective remains incomplete.

Doctors, meanwhile, pushed ahead, informally trying an array of methods to transplant fecal microbiota from healthy donors to the guts of patients—via enemas, tubes through the nose, and oral poop-packed capsules . Fecal microbiota transplants (FMTs) have been used to treat various ailments , from obesity to irritable bowel syndrome, to mixed success. But it quickly became apparent that FMTs were most readily effective at preventing recurrent infection from Clostridioides difficile (C. difficile or just C. diff).

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Space poses some massive dangers for humans, from black holes to the heat death of the universe. But as humanity considers long-haul space travel, there are other, smaller potential hazards that some researchers say may deserve more attention: microbes from Earth.

Astronauts face numerous known health problems in space, including a loss in bone density, muscle atrophy, and psychological issues . And on Earth, researchers are increasingly discovering how the various bacteria and other microorganisms that live inside and outside of people — the human microbiome — affect physical and mental health .

Space, of course, is an entirely different environment from Earth, with high radiation levels and microgravity. Although the science is far from certain, these vast differences may cause unexpected changes in the microbiome of astronauts. In turn, this could result in a range of health problems, which may be more pronounced on long-haul stints in space, like traveling to another planet.

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When you hear about the gut microbiome, does it ever make you wonder what tiny creatures are teeming inside your own body? As a microbiologist who studies the microbiomes of plants, animals, and people, I’ve watched public interest in gut microbes grow alongside research on their possible dramatic influence on human health. In the past several years, microbiome testing techniques used by researchers like me are now available to consumers at home . These personal gut microbiome testing kits claim to tell you what organisms live in your gut and how to improve your gut microbiome using that data.

I became very interested in how these home test kits work, what kind of information they provide, and whether they can really help you change your gut microbiome. So I ordered a few kits from Viome, Biohm, and Floré, tried them out, and sifted through my own microbiome data. Here is what I learned.

How do gut microbiome kits work?

All gut microbiome kits require you to carefully collect fresh fecal material. You put it in the various tubes provided in the kit and mail the samples back to the company. Several weeks later, you’ll receive a report describing the types of microbes living in your gut and suggestions on how to change your diet or activities to potentially alter your gut microbiome.