Here’s a fun party fact for you: The term “microbiome” was first coined in 2001 by microbiologist Joshua Lederberg to describe the collective organisms of bacteria species living in the gut. At the time, MDs had no idea all the secrets these bacteria families kept about each individual’s overall health; now, it’s safe to say that the scientific and medical communities are infatuated with the topic.

As of 2018 (the most recent data available), over 2,400 clinical trials were testing therapies on microbiome science. The focus has also birthed a slew of gut-testing apps and at-home tests, including microbiome testing company Viome (worth an estimated $45.5 million), microbiome medicine company Second Genome (which has raised over $42.6 million in funding), and microbiome engineering company Finch (which has raised over $77 million in funding).

Science has advanced so much in this area that the gut is now commonly referred to as the second brain by doctors and scientists. Clearly nothing has rocked the health world in the past decade quite like advances in gut health.

The most major gut-health findings of the past decade

To sum up 10 years of research, we’ve essentially learned that the health and functioning ability of your gastrointestinal system can impact the health of your entire body. “Through research, we have learned a lot about how gut health relates to a wide array of health conditions. It turns out that microorganisms can actually counteract the harmful effects of food, drugs, hormones in our bodies, either introduced from the outside or produced inside our bodies,” says Ian Smith, MD, best-selling author and chief medical advisor for the probiotics brand Jetson. “The sheer number of conditions that have been found to link back to gut health is in itself an exciting advancement: things like obesity, diabetes, liver diseases, cancer, and even neurodegenerative diseases,” he says.

Dr. Smith says there is also compelling new research that connects gut health to mental health (including anxiety, depression, and happiness.) “In the past 10 years or so, the number of studies that have linked gut health to mental health have exploded, including a great one that linked three probiotic strains to a lessening of depression in patients,” Dr. Smith says. “Ninety percent of all serotonin [a neurotransmitter linked to mood] is generated in the gut; mostly because we get tryptophan from our food to build it, so a healthy gut can produce the serotonin levels needed for a stable and happy mood.” Ten years ago, doctors may not have known that what you eat is connected to mental well-being, but it’s certainly a growing focus of discussion now.

A growing body of research also suggests that the types of food we eat can impact the functioning of our gut microbiome. A 2018 study found that people who ate at least 30 different types of plants per week (including vegetables, grains, nuts, and seeds) tended to have the healthiest guts, while diets high in sugar and saturated fats have been associated with altered gut flora. While there is still much more research to be done to understand these associations, the connection between diet and gut (and thus, overall health) is crucial, says Naveen Jain, an entrepreneur, philanthropist, and CEO of Viome.

“Microbial function, not composition, is the driving force behind chronic conditions like depression, obesity, and even certain types of cancer,” Jain says. “This discovery is hugely exciting because it [could enable] us to treat, reverse, and prevent these diseases, just by modulating the microbiome with personalized nutrition.” He believes that the bacteria in your gut can clue you in on what’s causing inflammation in your body. Some culprits, like sugar, cause inflammation in everyone, while others, like dairy or wheat, are more individualized. Jain (and a number of other experts) believe people could use this intel to limit their exposure to what’s harmful for their body, therefore putting themselves at reduced risk for everything from digestive distress and acne to chronic disease.

Check out the video below for a registered dietitian’s guide to gut health:

The at-home gut-testing market has risen to meet the demand of people—including those who don’t have access to specialists—who want more intel into what foods they need to eat more or less of to better their overall health. Other companies are using AI technology to pinpoint health issues just by looking at photos of poop via an app. Of course, this is a relatively new (but growing) field, and there’s a lot we are still learning about how the microbiome and the gut interact with the rest of the body. Some researchers caution that we don’t quite know enough yet to definitively tell people what to eat to create specific gut changes for their individual needs. But again, given that there were over 2,400 clinical trials looking at different aspects of the microbiome in 2018 alone, it’s safe to say we’ll be learning more and more each coming year.

What’s next for gut health

Dr. Smith believes personalized gut-health programs—tied to what specific individuals should eat for optimal health—will continue to explode in the next decade. “Researchers are continuing to zero in on more specific aspects of gut health, including what functions various organisms in the microbiome perform, and how we might continue to personalize the treatment of gut health on an individual basis,” he says. “According to what we’ve discovered so far, the gut features more than 10 trillion microbial cells that come from around 1,000 different bacterial species, so there is still plenty to research. Scientists have already isolated and published information about some of these strains, which have been made available in a sort of ‘library’ to help inform research and study.”

Jain believes gut health tech will continue to get better and more affordable with time—a boon for people who can’t currently afford the kits (Viome’s retails for $149) or even more expensive testing at a doctor’s office (exceeding thousands of dollars). “The technology we use to analyze the microbiome is advancing at such a rapid pace that we’ll be able to do so much more within the next 10 years. Individuals will be able to take control of their own health by creating a virtual model of their own biology—no more expensive hospitals, complicated tests, or confusing second opinions,” he says. “Science-based and personalized, preventative medicine will be a reality for everyone.”

In fact, when I first met Jain almost four years ago prior to the launch of Viome, I remember him telling me his hope was that his microbiome test would become so widely used by people (and hospitals) that he could sell it for $1 and offer it to doctors working with people in developing nations for free. Fast-forward to the present, and he still hopes that gut-health technology will democratize health care. “Today, chronic disease or cancer is a matter of bad luck,” Jain says. But he’s confident that microbiome medicine will change that reality.

These are the golden rules of gut health, according to doctors. Plus, six foods a gastroenterologist wishes everyone would eat more of.