Want to hear about a messed-up study? Of course you do.

Here’s how scientists measure the will to live: Separate a young rat from his mother, throw him in a pool of water with no exit, and see how long it takes him to stop optimistically swimming in circles and start sadly treading water as he waits for the inevitable sink to the bottom. It’s a test to measure how long it takes to give up on life.

Don’t worry, the rat lives through it. We’re only bringing this up because in one such experiment in 2010, scientists found if the rat had been consuming probiotics, it was less likely to suffer from that anxiety and despair after being separated from its mother and tossed to its watery doom.

That’s right: Probiotics—the so-called “good” bacteria that are often found in yogurt and help with digestion—might increase our will to live.

The Role of Bacteria in Your Health

One of the most exciting and revolutionary topics in health right now is also one of the least sexy: We’re talking about the bacteria that live in our digestive tracts—what science types call the gut microbiome. Our bodies play host to trillions of these critters, and they make up a mini-ecosystem that helps us break down the food we eat and absorb its nutrients. At least, that’s all we thought the microbiome did.

Recent research has shown that our belly bacteria have an incredible impact on everything from fat loss and inflammation levels to perhaps even our susceptibility to depression and anxiety.

The Value of a Diverse Microbiome

Let’s start with the fat loss. Your gut bacteria has a huge effect on your insulin sensitivity, which controls the way your body responds to carbohydrates—specifically how likely it is to turn them into fat. Essentially, increasing your insulin sensitivity makes it easier to burn carbs.

So how can you manipulate your microbiome into helping you burn more fat?


“You’ve got trillions of bacteria that help you digest food,” says Brad Pilon, a nutrition consultant and lead researcher on Flat Belly Forever, a weight-loss system that cuts body fat by optimizing your gut bugs. “But when you don’t have enough kinds of bacteria in there, it can contribute to a lot of issues with your health, and there’s a real correlation with low gut diversity and obesity.”

In one quirky (if, again, kind of messed up) study, scientists pulled the gut bacteria out of obese mice and put ’em into the bellies of regular mice. Having the gut bacteria of obese mice increased the healthy mice’s body fat even though their diet didn’t change. And multiple human studies have also shown that crummy gut diversity leads to more fat storage and poor insulin sensitivity. A lack of gut diversity is also a really important marker of inflammation, which is linked to obesity, heart disease, arthritis, and even depression.

The Gut-Brain Connection

That brings us back to our water-logged rodent pal from the beginning and how probiotics can make rats (and even humans) less anxious: the so-called gut-brain axis.

The fact that the brain and belly are linked isn’t surprising. (After all, indigestion is a fairly well-known side effect of stress.) But we’re now learning that connection is a two-way street: The mind can affect the gut, and the gut can affect the mind.

Here’s a good example: In 2011, British scientists gave probiotics to both rats and human subjects. After a month, they noted a significant decrease in both the rats’ anxiety-like symptoms and in the humans’ levels of anger, distress, hostility, and depression. More recent research out of Oxford showed that supplements designed to boost the numbers of healthy gastrointestinal bacteria may improve anxiety levels by changing the way we process emotional information. The participants were actually found to pay less attention to negative words and more attention to positive words after three weeks of supplementing.

“Some people think this is a little out there,” Pilon says. “But after all, we accept that your kidneys affect brain function, and there’s evidence the liver might be involved with multiple sclerosis. If you start viewing the microbiome as another organ, it makes a lot of sense.”

What You Can Do

Each day brings new findings about how the bacteria in our gastrointestinal tract affect systems throughout the body. And each day we catch a glimpse (and a whiff) of our own GI, er, output. Taking advantage of the many benefits of diverse, healthy gut bacteria isn’t as easy as eating yogurt every single day—but it’s not much harder either. Follow these simple steps:

1. Determine whether you’ve got a problem in your gut.

If you have diarrhea, constipation, or stomach cramping all the time, this isn’t even a question. But there are other signs your gut isn’t as healthy as it could be.

“The notion of optimal digestive health can’t be compared from one person to another,” says Pascale M. White, M.D., assistant professor of medicine and director of the gastroenterology clinic at the Icahn School of Medicine at Mount Sinai in New York. “Everyone has their own baseline.”

That means whether you normally have three bowel movements per day or one every other day, a change from your individual baseline could mean there’s something wrong, White says. Other signs of intestinal issues are increased bloating, heartburn, or stomach pain.

Due to what we now know—or at least suspect—about the microbiome, you might even look to other parts of your body for signs of an imbalance in your GI tract.

The gut is like our second brain; it’s very predictive of the other things that happen in our body,” says Deepa Verma, M.D., AIHM, an integrative health physician. “Eczema, rashes, psoriasis, depression, anxiety, migraines, headaches… concerns that manifest outside the gut can be linked back to it.”

2. Keep a food diary.

We’re not always paying the best attention to the cause and effect of what we do to our bodies, so this is where White often starts with her patients.

“It can help them look at what they are eating in relation to what they are feeling,” White says.

Often, people are surprised by patterns they find, she says, and this gives them a much clearer idea of what foods to eliminate from their diets. You may find, for instance, that you’ve developed a lactose intolerance, which is something that often happens in adulthood.

3. Check up on yourself.

Everybody’s body is different, and that’s true for our guts, as well. If you want to learn more about your own body’s ecosystem and its particular needs, a home microbiome-testing kit may give you personalized insight into what steps to take to optimize your gut health. We’re fans of Viome (read more about it here), and for a super-limited time, you can get $100 off when you use code GREATIST2 at checkout.*

4. Eat more fiber.

Isn’t it nice to think about adding foods to your diet rather than eliminating them? That’s the approach Amy Gannon, M.Ed., R.D., L.D., department manager of eCoaching at the Cleveland Clinic Wellness Institute, takes to improving the gut microbiome.

“The easiest dietary fix across the board would be to include whole foods that have dietary fiber—even better if those foods can be a source of prebiotics,” she says.

Gannon suggests eating more of all kinds of fruits, vegetables, lentils, and whole grains to get fiber, which ferments in the intestines. Prebiotics are foods that break down into chemicals that feed good bacteria. Onions, garlic, leeks, and oats fall into this high-fiber, prebiotic category.

While you’re at it, you should also know that your gut will benefit from having an extensive menu, because variety, apparently, is the spice of microbiota.

“Foods have different benefits that promote different kinds of bacteria—so apples, artichokes, and pistachios benefit a certain kind of bacteria,” Gannon says. “Then other foods, like yogurt, have a different kind of bacteria.”

5. Eat fewer inflammatory foods.

“I don’t expect all my patients to be plant-based or vegan, but I do expect them to at least limit the amount of animal products that they consume because meat and dairy are very inflammatory,” Verma says.

Studies have shown that the staples of our “Western” diet (high in sugar, starch, and saturated and trans fats) cause an inflammatory response. Inflamed intestines lead to poor absorption of nutrients and more serious conditions such as Crohn’s disease and inflamed bowel syndrome. Verma suggests limiting meat and dairy to about 20 to 25 percent of your diet, with the rest being plant-based. That gives you plenty more opportunities for adding those high-fiber foods too.

6. Eat (the right kind of) fermented foods and yogurts.

If you know nothing else about good bacteria, you probably at least know they’re in yogurts. Fermented foods such as kimchi, tempeh, and miso are also excellent sources of probiotics. But you have to pay attention to the labels: The yogurt should say it has “live active cultures,” and the fermented foods should be the refrigerated kind, not the shelf-stable versions that have been pasteurized—a process that kills off bacteria.

“The beauty with these food sources is that you’re getting probiotics, and you’re also getting other nutrients along with them,” Gannon says.

By the way, there’s no prescribed amount of these foods you should eat—the science is still too new for that kind of precision. For now, Gannon says you can let your taste buds guide you rather than treating them like medicine.

“With some of those foods, they do have benefits, but if you don’t like them, then I definitely wouldn’t force yourself to eat them,” she says. “It really is important to go with things you like and can include day to day.”

Also, probiotic supplements can be beneficial, but there’s no magic pill here—adding probiotics blindly without fixing other issues isn’t a good solution.

7. Look at the FODMAP list.

After doctors have ruled out organic or structural GI disorders (such as infection, colitis, cancer, colon polyps, Crohn’s disease), they turn to the much more vague diagnosis of irritable bowel syndrome. White says the priority for IBS is to treat the symptoms (diarrhea, cramping, constipation, gas). The food diary is one way to begin identifying IBS triggers, and another is looking at the list of foods high in fermentable oligosaccharide, disaccharide, monosaccharide, and polyols, a.k.a. the high-FODMAP foods. The way these foods break down produces gas, which is problematic to those with hypersensitive systems.

“Each patient is different, so some patients may look at the FODMAP-eliminating diet and say, ‘Apples never bothered me, but when I have corn syrup, it does bother me,'” White explains. “It’s not as if they have to completely avoid those foods. It’s more like you look at the list and determine which ones you’re eating more of that you didn’t realize could be contributing to your symptoms.”

8. Sleep more.

There is conflicting evidence about whether sleep deprivation actually negatively impacts the human microbiome.

What we do know, however, is that lack of sleep does increase levels of cortisol (a.k.a. the stress hormone) in your body and that stress affects your gut in a number of ways.

“Some studies say that chronic stress can induce a dysbiosis, or abnormal growth pattern of gut microbes,” White says. Her patients with IBS also often identify stress as a trigger for their symptoms.

Cortisol also causes inflammation, which can be another source of problems in digestion and beyond. “Inflammation impedes natural processes like digestion and metabolism that are crucial for us to thrive and survive,” Verma says.

Gannon adds that melatonin, the hormone that makes us sleepy, is produced in the gut, which adds to this particularly nasty cycle.

9. Exercise regularly.

This is another way to decrease the stress that could be disrupting your gut, thanks to those endorphins it gets pumping through your brain.

“Exercise is awesome in that it’s one of our most underutilized antidepressants and anti-anxiety agents,” Verma says.

Just last year, scientists at the University in Illinois looked at the gut microbiota of lean and obese people when they were exercising regularly and when they were sedentary. During periods of exercise, both the lean and obese groups had an increase in the kind of microbes that produce the short-chain fatty acids our bodies need for a whole host of functions, including digestion.

10. Be careful about antibiotics.

Downing antibiotics can be a doctor’s first response to conditions as common as bronchitis, sinus infections, and sore throats. But these pills kill off massive amounts of both “good” and “bad” gut bacteria (“anti-biotic” is literally the opposite of “pro-biotic”). Worst of all, exposure to antibiotics at a young age may even influence whether a person will develop diabetes or Crohn’s disease later in life. Try to explore alternatives whenever possible.

11. See a primary care doctor regularly.

Most young adults visit a doctor only when something is wrong. That means you never have a doctor who knows what you look like when you’re healthy and therefore they won’t be as helpful in diagnosing your problems.

“Having that person keep an eye on you on a continual basis is your first line of defense,” White says. “That primary doctor is, over time, going to know you. Then when you step out of that normal boundary, they will be able to direct you to more testing they can do or to a specialist like me.”

The Takeaway

We weren’t kidding when we said practically every facet of your health is affected by an invisible alien ecosystem in your gut that you’ve probably never given much thought to. It’s kind of crazy, but it’s also important: At a time where there are rising rates of obesity and type 2 diabetes across America, we need to start thinking more about the microbiome and the role it can play in managing those health issues. Luckily, tending to your gut bugs doesn’t have to be complicated: Eat fermented foods, sleep a lot, fill up on fiber, and maintain a healthy weight. Your belly and your brain will thank you.

The experts interviewed in this story are in no way affiliated with Viome.

*Offer valid through October 31, 2018, 11:59 p.m. PT. Greatist receives an affiliate fee for purchases made.