Brushing your teeth might help change your mood or prepare you for a good night’s sleep. It’s simple advice for good oral health. But the reality is that your mouth is one of your body’s most complex places. Partly because it’s the gateway to your digestive tract. And with everything you put into your mouth on a day-to-day basis, you’re inviting and hosting scores of different types of life—collectively known as the oral microbiome—inside your oral cavity.

It might sound a little scary, but there are colonies of bacteria everywhere inside your mouth. On your teeth. In your gums. On your tonsils. Beneath your tongue. On the inside walls of your cheeks.

The oral microbiome contains over 700 prevalent species of bacteria, according to the American Society of Microbiology. And all of these various bacteria come to hang out and play their part in your oral and overall health.

That’s right. There’s a big connection between oral health and your long-term health. But what do the different types of bacteria living inside your mouth provide in terms of functionality? What influences the makeup of these varying types of microbes? And perhaps most importantly, what’s the key to maintaining a healthy balance of oral bacteria?

Science helps break it down.

Why Oral Bacteria Exists

The fact is, bacteria and other microbes are almost inescapable. They live everywhere around you, on you, and inside you. That’s prompted experts to refer to these microbes as “permanent guests.”

The oral microbiome is no different. Various bacteria and microbes contribute to health—positively and negatively. And this complexity has been a topic of focus among cell biologists, microbiologists, and immunologists over the last decade. These microbial communities create a fascinating world for experts to explore. Purnima Kumar, professor of periodontology at Ohio State University, said every time a person drinks a glass of water, they’re swallowing millions of bacteria.

Kind of gross. Also fun to think about, right? But it’s not much fun for the residents of the oral microbiome.

There’s a battle raging inside your mouth. It’s a life-or-death fight for space and food. And the outcome is important to you. Some bacteria in what is also called your biofilm help protect your mouth and maintain the health of your teeth and gums. Others create issues for your dental health.

The ongoing fight between the good and bad sides can be easily swayed based on things you do. That includes behaviors—like diet and poor oral hygiene—as well as recurring health problems. One interesting development scientists have figured out is your overall oral health is generally influenced by your mother’s oral health. That’s because you’re more likely to be born with similar bacteria.

That’s right—you weren’t born with teeth, but you’re born with oral bacteria.

It’s Time to Start Caring About the Composition of Your Oral Microbiome

You know that gross feeling when you wake up every morning? With the film on your teeth and your breath not at its best—to put it kindly? What if that was permanent? No thanks.

The easy answer to this issue might be to remove all the bacteria in your mouth so you don’t have to feel that way. But if you wiped away all the bacteria in your mouth, you would be ridding yourself of those that work on your behalf, too.

Certain bacteria fighting on your team can help your breath stay away from nasty territory. On top of that, some bacteria of the oral microbiome work to break down foods in an enzymatic reaction that starts with your saliva.

Some strains of bacteria like Streptococcus and Neisseria are linked in studies to the maintenance of esophageal health. And Neisseria has proven to play a part in the breakdown of toxic substances like tobacco smoke.

There are bad guys in there, too. And they can have their say both in the short-term and the long-term health of your mouth. So, the important thing is to create a balance of bacteria that is beneficial to your health. Just like you can do in your gastrointestinal tract.

It’s all about space and food. That starts with good hygiene. Experts will tell you what your parents have said all along: brush and floss to keep bacteria under control. That’s why when you let oral care slide for a while, things in your mouth can get dicey. Bacteria levels can rise, which could cause issues for your teeth and gums.

There are other factors you might not think of—like saliva. It helps wash away lingering bits of food and provides protection from acids produced by bacteria. But some medications can reduce the flow of saliva in your mouth. Be aware of this if you take some decongestants, antihistamines, and antidepressants.

Your diet also plays a role in the health of your mouth and your oral microbiome. That means concentrating on a healthy diet that supports the growth of good bacteria instead of bad ones. Adding an oral probiotic also might be useful to support a healthy balance for your oral microbiome. You’ll find more tips later on in the story.

What Kind of Bacteria Live in Your Mouth?

Don’t worry, there’s no way to cover all the types of bacteria in your oral microbiome on one page. There’s simply too many. Covering the hundreds and hundreds of different species would require a full book.

But here are some common types of bacteria you should be familiar with:

• Streptococcus: One of the largest players in the oral bacteria community, there are several different strains that fall under the Streptococcus family. Usually they are oval-shaped chains of bacteria cells. And some can cause issues for your teeth. Streptococcus mutans, for example, is a potential pathogen that can convert sugar to lactic acid. And that acid buildup is bad for your teeth.
• Porphyromonas gingivalis: This is one type of bacteria you don’t want to see show up. Luckily it isn’t usually present in a healthy oral microbiome. Avoid it to maintain the health of tissues and bone structures that support your teeth.
• Lactobacillus: These strains are long, rod-like bacteria that have thick cell walls. Like Streptococcus strains, Lactobacillus helps change lactose (a milk sugar) into lactic acid. This means more acids that shouldn’t be allowed to linger in your mouth. But Lactobacillus is a beneficial bacteria for your gut, which is why it’s in many probiotic products.
• E. Coli: Most E. coli in the human body is found in your guts, but a trace amount of the bacteria is also part of the oral microbiome. Thankfully, not all E. coli strains are alike. And these aren’t the same as the ones you hear about on the news from contaminated foods.

The oral microbiome’s residents are created equal. In fact, different strains of the Streptococcus family actually are helpful. Streptococcus salivarius K12 aids in fighting bad breath. Like you read above, Neisseria helps breakdown bad substances like cigarette smoke, and some strains help break down food.

It’s not currently possible to design your bacterial mix to be purely good. So, maintaining a healthy balance in your mouth microbiome is what’s important. And there are several ways you can support this healthy balance.

Tips to Maintain a Healthy Balance of Oral Bacteria

There will always be a variety of neutral, harmful, and helpful oral bacteria renting out space in your mouth. That’s just the reality of the situation. Don’t fret, though. There are simple answers for keeping your oral microbiome in good shape.

First and foremost, it’s about maintaining the necessary level of oral hygiene. Brushing—twice a day—and daily flossing keeps bacteria at bay.

Your lifestyle and diet also have a big impact on the bacteria in your mouth. A healthy, whole-food diet that’s mostly plant-based is a great start. You also need to avoid things that stimulate the growth of bad bacteria. Sugar is a big source of food for oral bacteria. Also stop smoking—or, better yet, never start. Nicotine is damaging to your oral microbiome. Stress is also as bad for your bacteria as it is for you.

Oral probiotics can also help add more beneficial bacteria to the microbiome, too. Researchers have found that supplementing with oral probiotics can be a useful tool in supporting and maintaining the health of your mouth. Oral probiotics are generally chewables or in tablets of various forms that allow the bacteria to set up shop in your mouth and adapt to their new environment.

The gateway to your body is one of the most complex parts of you. Understanding what’s going on inside your mouth and your oral microbiome can help maintain your long-term health. The oral microbiome is the initial line of defense for your overall health, so start taking steps to care for it every day.

Your favorite foods take a wild ride after you take a bite. Picture a go-to snack and consider its journey through your digestive system. Take a ripe, juicy apple, for example. The fruit is full of nutrients for your body to use.

But how does that fruit become usable in your body? After all, your blood isn’t pumping microscopic apples through your arteries and veins. Your body is utilizing the chemical compounds that make apples crunchy and sweet.

Those compounds are extracted from your food through the digestive process. It’s the method by which your diet’s fats, sugars, proteins, fiber, and essential vitamins and minerals—as well as other important nutrients—find their way out of the food you eat to power your body. Digestion also removes waste. And this process is constantly going on in your body.

From dinner plate to elimination, the food you eat takes a long trip through your digestive system. Take a look at the path your food will follow as it is digested:

Mouth >> Esophagus >> Stomach >> Small Intestine >> Large Intestine

At each step along the digestive journey, food is modified and broken down into usable pieces. By modeling this system step-by-step, you can gain a better understanding of the fate of your food after it enters your body.

Learn the Language of Digestion

Before exploring the ins and outs of the digestive system, let’s brush up on the vocabulary. Knowing the words associated with the digestive process will make learning about it a piece of cake.

• Bolus: chewed food mixed with saliva.
• Pharynx: throat, the space that links the mouth to the esophagus.
• Sphincter: ring of muscle that controls passage of liquids and solids from one organ to the next.
• Chyme: mix of broken-down food and digestive juices that leave the stomach and travel through the small intestine.
• Villi: microscopic, finger-like projections that cover the walls of the intestine.
• Bilirubin: pigment released as the result of red blood cell degradation.
• Stool: waste remaining after digestion.

Mouth

Eating is by far the most enjoyable part of the digestive process. Your mouth and tongue encounter foods and beverages of all varieties, textures, and tastes. And together, they begin digestion by breaking up the food you eat into small, easy-to-swallow pieces.

You may think digestion begins the moment you take a bite. But in some case, it starts even before that. The sight, smell, or thought of food can be enough to trigger your salivary reflex. That’s why your mouth waters when you’re hungry. Saliva is also produced with the chewing motion. It moistens and lubricates food, making it easier to swallow.

Think of the apple. In the afternoon, when you need something to tide you over until the evening meal, an apple is a great choice. Just thinking of the crunchy fruit and the sweet, tangy, juice can make your mouth water.

The salivary glands in your mouth secrete saliva, which is rich in the digestive enzyme amylase. Salivary amylase breaks apart starches into two-chain sugars called maltose. This simple sugar will later be broken down further into single glucose molecules that can be used as cellular energy.

The movement of the tongue is also important in the digestive process. After food is chewed up and mixed with saliva, it’s ready to be swallowed. Your tongue molds and mashes food into a bolus and guides it to the back of your throat. As you swallow, the bolus of food is pushed through the pharynx and into the esophagus.

Digestive Tract Fact #1 – The salivary glands in your mouth secrete between one and one-and-one-half liters of saliva every day.

Esophagus

Boluses of food are shuttled from the mouth to the stomach via the esophagus. This key connector is guarded by two sphincters at the upper and lower ends. These round muscles act like purse strings that open and close as you swallow.

Each sphincter works independently. The upper esophageal sphincter ushers in boluses from the pharynx. The lower esophageal sphincter empties the contents of the esophagus into your stomach. It can also open to release gas build-up from the stomach. This causes you to belch.

The force that propels food and drink through the esophagus is called peristalsis. The smooth muscles that line the esophagus undergo regular contractions after a bolus is swallowed. The wave-like movement created by peristalsis continues throughout the digestive tract. The motion pushes food through all phases of digestion, in the stomach, small intestine, and large intestine.

Gravity can also aid in moving a meal through your esophagus. By sitting upright, the food you eat can travel swiftly and comfortably down the esophagus and into your stomach.

Digestive Tract Fact #2 – It takes only eight seconds for a bolus of food to travel from the pharynx, through the esophagus, and into the stomach.

Stomach

As you bite, chew, and swallow, boluses of food are dropped into your stomach. The stomach acts as a storage unit that accepts small packages of food over the course of a meal. A large quantity of food can be quickly stored and then digested over a long period of time.

This is remarkable because, when empty, an adult stomach has a capacity of 75 milliliters. But it can stretch and house up to one liter of food over the course of a meal. That’s over 10 times the starting capacity.

Let’s say you decide to eat more than just an apple. Instead you have yogurt, a turkey sandwich, and some carrots, too. That is a lot of food for your body to store in one sitting. Since your stomach is designed to accommodate full meals, you don’t need to worry about bursting at the seams. Your tummy will take each bite in stride, and process the full meal over the next several hours.

The stomach is a dynamic organ, too. It churns, squeezes, and grinds boluses of food and mixes them with gastric secretions. Peristalsis continues in the stomach and is the driving force for blending food with stomach acid. Stomach secretions help make nutrients available for absorption later in the small intestine.

This digestive juice is powerful hydrochloric acid. It’s strong enough to break apart tightly bound proteins into polypeptide chains (smaller chains of amino acids). It can also eliminate potentially harmful bacteria that may be present in some foods.

Since stomach acid is so potent, its production needs careful supervision. At the start of a meal, gastric function is just starting to warm up and very little stomach acid is secreted. Peristalsis gently begins stretching and squishing the stomach in preparation for incoming food.

In the middle of a meal, peristalsis and stomach acid rev up. Gastric secretions are at an all-time high mid-meal. The muscular stomach is rapidly mixing food and drink with hydrochloric acid. This ensures plenty of fluid in which to break down each bite of food. After food is liquified, it is referred to as chyme.

Peristalsis helps pump chyme into the small intestine while you eat. Once your meal is over, stomach acid secretion comes to a halt. But there may be excess acid. When too much gastric juice remains in the stomach after a meal, irritation of the stomach lining can occur. To protect itself, the stomach adjusts acid production to stay healthy and keep you comfortable.

Stomach contractions continue until all the chyme from the previous meal has entered the small intestine.

Digestive Tract Fact #3 – Stomach rumbles are produced by peristaltic contractions as they move contents through the intestinal tract. They occur during digestion and can continue two hours after the stomach has emptied.

Small Intestine

The small intestine plays the most significant role in the digestive process. And it’s anything but small. At 22 feet (seven meters) long, the small intestine’s primary role is nutrient absorption. Along those 22 feet of digestive “pipe,” several forces combine to optimize small-intestine function.

The lumen (center) of the small intestine is covered in tiny, finger-like tentacles called villi. These densely packed hairs give the mucosa (mucous membrane) of the small intestine a velvety appearance and help their function.

Think of villi like a densely packed carpeting, soaking up every usable nutrient in sight. The purpose of these villi is to increase the surface area of the small intestine. As chyme is further digested, nutrients are absorbed through the villi and transported to the blood stream. A larger surface area means more absorptive space.

Let’s go back to that apple. The fruit-and-stomach-secretion cocktail (chyme) enters the small intestine and mixes with water and other digestive juices like bile. Rhythmic stirring of chyme continues the breakdown of sugars, fats, and proteins from the apple or whatever your previous meal was.

Bile is critical in the digestion of fats into free fatty acids. Bile is composed of water, salts, acids, and lipids. It is a medium in which fats and fat-soluble vitamins can dissolve and be carried into the blood stream via the villi.

Bile also contains bilirubin, a yellow-orange pigment released by red blood cells as they break down. Your body can’t metabolize bilirubin on its own, so it relies on bacteria to help out. When the bacteria in your small intestine chow down on bilirubin, they produce a dark material called sterobilin. This by product gives stool it’s notable brown color.

You also get some help breaking down your food. Microbes in your small intestine do a lot of work to help make fatty acids available for later use. They work alongside secretions from the pancreas (called proteases) that help digest proteins. Proteases break apart complex proteins into peptide chains, then further into individual amino acids.

Now, glucose molecules, amino acids, and free fatty acids are available to be absorbed into the blood stream through the villi.

Digestive Tract Fact #4 – It takes four to five hours for the stomach to completely empty into the small intestine after a meal.

Large Intestine

At end of the journey through the small intestine, most nutrients from digested food have been absorbed. But not everything you eat is an absorbable nutrient. So, what happens to the parts of your food that your body doesn’t need? In the large intestine, undigested material, excess fluids, and mucus all combine to form stool. (There are many more colorful names for it, but stool is the preferred medical term, and what you’ll see moving forward.)

Stool is the solid waste of the digestive process. Believe it or not, your body doesn’t use every particle of food you ingest. Roughage (fiber) travels through the digestive system relatively intact. This is because the digestive enzymes produced in the body cannot break down fiber.

Your snack from earlier, the apple, is a good example of this. The compounds that make the apple skin tough and give the fruit its characteristic crunch pass right through your digestive system with very little nutrient absorption.

Undigested bits of food and fiber accumulate in the large intestine. This final stop on the digestive journey is full of pockets of tissue called haustra. They give the large intestine its puckered appearance. Haustra can stretch to accommodate large amounts of stool as it prepares to leave the body.

The exit of the large intestine and end of the digestive journey—when solid waste is eliminated—is another sphincter called the anus. But in order for stool to leave the digestive tract, it needs a little momentum.

A bowel movement is necessary for your body to expel stool from the large intestine. Very strong peristaltic contractions (the wave-like movements from earlier in the trip through the digestive tract) move stool toward the exit. This creates feelings of pressure in the region and eventually triggers the defecation reflex.

Solid waste is characteristically brown and stinky. You know that bilirubin gives stool its color, but what causes its odor?

If you guessed bacteria are involved, you’re right.

Microbes that reside in the large intestine make a meal of the leftovers from the small intestine. As they interact with stool, gas is created. The smell associated with stool comes from the gases released during the break down of solid waste by bacteria.

Digestive Tract Fact #5 – Stool can sit in the large intestine for up to 48 hours before it is expelled from the body.

Tips for Healthy Digestion

When your digestive system runs smoothly, you feel healthy and comfortable. There are simple ways to keep your tummy in tip top shape.

Let’s start with water.

Ample hydration makes the material in your intestines move easily with each wave of muscle contractions. Drinking plenty of water also helps soften the waste that lurks in your gut. When stool is eventually collected in the rectum, water makes it more comfortable to eliminate.

Fiber also eases digestion.

The complex carbohydrate is bulky and adds weight to stool. Bowel movements are easier to pass when solid waste is heavy. Fiber also absorbs water and softens stool as it travels through the digestive tract. Consider increasing your fiber intake if you notice irregularity in bowel movements. Remember, elimination of solid waste can be different for each person. One study found that normal elimination patterns varied from three times per day to three times per week.

But be careful, adding too much fiber too quickly can have unpleasant consequences. Intestinal gas build-up, bloating, and abdominal discomfort can be the result of ramping up fiber intake too quickly. So, increase the amount of fiber in your diet slowly to maintain intestinal comfort. Look for natural sources of fiber to add to your diet. These include:

• Fruits
• Vegetables
• Nuts
• Beans
• Whole grain

Another way to improve digestive health is to take care of the bacteria living in your gut. These microbes do a lot to facilitate healthy digestion. By utilizing probiotics, you can help maintain a healthy balance of intestinal bacteria.

Probiotics support the numbers of helpful microorganisms in your gut. They also aid in nutrient absorption in the small intestine and help break down your food. There is growing evidence to suggest that probiotic supplementation may play a role in supporting immune health, too.

Take a closer look at the digestive system and consider the path your food takes. It is remarkable how your favorite meals are torn apart, liquefied, absorbed, and eventually eliminated by your body. And it’s all to harvest the essential nutrients you need to survive.

So, support your digestive system with lots of water and a high-fiber diet. And make its health (and yours) a priority.

About the Author

Sydney Sprouse is a freelance science writer based out of Forest Grove, Oregon. She holds a bachelor of science in human biology from Utah State University, where she worked as an undergraduate researcher and writing fellow. Sydney is a lifelong student of science and makes it her goal to translate current scientific research as effectively as possible. She writes with particular interest in human biology, health, and nutrition.

You’re never alone. Your body is always crawling with trillions of microbial friends. That’s not a bad thing. All of them make up your microbiome—a word you hear a lot, but might not completely understand. Defining microbiome is actually pretty simple. It’s the collection of bacteria, fungi, protozoa, and viruses mentioned above. But don’t let the simple definition fool you. The microbiome is an expansive topic to discuss.

If this is your first time hearing about the microbiome, stay calm. There’s no reason to pull out the sanitizer. You shouldn’t feel gross or unclean. And your skin shouldn’t crawl because you’re an ecosystem for trillions of bacteria and microbes.

The microbiome is a normal part of a healthy life. Many studies suggest that your community of microbes could even play a large role in your health.

If you’re still a little uneasy, an introduction to your microbiome might help. So it’s time to go beyond defining microbiome and introduce you to your bacterial buddies.

A Bit of Basic Bacteria Biology

Other microbes live in your microbiome, but bacteria are the most studied, dominant portion. They’ll mostly be the focus of our attention moving forward. And basic information about bacteria is a great place to start the deeper discussion of the microbiome.

The first thing to know about bacteria—there’s a lot of them. Bacteria rule the earth, even though you can’t see them with your naked eye.

They make up the largest percentage of life on earth. Bacteria weigh more in total than all the humans on earth. One estimate puts the total number of bacteria at about five million trillion trillion. That’s a number so big it doesn’t even have a name. But it’s a five with 30 zeroes after it.

Second, bacteria are in the prokaryote domain. They’re single cells with a primitive outer membrane, no specific cellular parts, and no distinct nucleus. All the ingredients for life—DNA, proteins, and more—float around in the cytoplasm (a cellular liquid).

You fall under a different biological umbrella. Humans, animals, and other complex cellular life belong in the eukaryote domain. That’s because we’re multicellular organisms with membranes around our cellular organelles (cell parts with specific functions) and nuclei.

Your Body and Bacteria

Now that the basic biology is out of the way, it’s time to focus on the bacteria and microbes you interact with. Let’s start with the numbers.

While there’s more bacteria than about anything on earth, that’s not exactly the case with your body. Old estimates had microbiome cells outnumbering yours 10-to-1. Recent research suggest the ratio is closer to 1-to-1. That’s a tenth of what was once thought, but that means you’re still living with trillions of bacteria.

And there’s a great variety of bacteria and microbes inhabiting the communities created by your body. For example, your skin, nose, mouth, ears, and armpits all have very different inhabitants. There is even a difference in who is living between your toes versus other parts of the feet. Your gut—the place our mind goes first when say microbiome—can contain 40,000 different strains and species alone. This diversity is important, because it creates competition for space and food.

Like any lifeform, bacteria are selfish. They don’t live with you because they’re heroes and helpers. Bacteria’s biological imperative is to provide for themselves and their descendants. Luckily, your body has evolved to use the selfishness to its advantage. This creates a win-win situation (symbiosis). The bacteria get food and the body uses compounds produced by the bacteria.

These mostly productive relationships make it easy to think of bacteria as good or bad. That’s an oversimplification of the situation, though. There are some black-and-white cases—pathogenic bacteria that are out to harm you. But the majority of fall into a grey area because most are typically harmless or provide a slight benefit.

How you view specific bacteria (good or bad, healthy or harmful) has a lot to do with location. In one area of the body, a strain of bacteria can be beneficial—aiding in digestion or healthy immune function. In another area, that same type of microbe can cause problems. Sheer numbers can also present issues. For example, a weakened immune system can allow a strain of bacteria to multiply and grow to a population that’s problematic.

And the bacteria don’t suddenly decide to turn from heroes to villains. That’s not how they work. Bacteria act about the same all the time. They’re always selfish. And they’re always trying to multiply. But when they’re in the wrong place—where condition aren’t favorable for symbiosis—or they grow to large numbers, the microbes can wreak havoc.

But if bacteria are mostly harmless, and we shouldn’t call them good or bad, what’s the deal with probiotics? There are certain strains of bacteria that research has shown to provide benefits in certain situations. But in the context of your total bacteria—the trillions of cells and thousands of strains—those are rare, specific cases. That’s why it’s important to get probiotics that are tested and proven to survive in the right bodily environment and demonstrate benefits.

Finding Your Microbiome

Most people hear “microbiome” and think about the gut. Your lower digestive tract is packed with microbes. But it’s not the only place you can find different communities of diverse bacteria.

Let’s go through them:

• Gut: Your stomach doesn’t contain much bacteria. High acidity creates an uninviting environment where few can survive. Your intestines are a different story—mostly because that’s where food stays for the longest time. The gut microbiome has been extensively studied, so we can name many of the bacterial categories you’d find in your intestines.
• Both the small and large intestines are packed full of a variety of microbes, but Bacteriodetes (another category of bacteria) are very prevalent. And you’ll find distinct populations of bacteria in the small intestine and the large intestine, with different strains dominating each.
• Skin: Your body’s largest organ has its own community of bacteria and microbes. If you’re a germaphobe, this confirms your worst fears. You really are covered with bacteria. All the folds, nooks, and crannies of your skin provide ample space to develop diverse microbial communities. Remember, the vast majority are harmless in normal circumstances. And most of them can be categorized as Actinobacteria (a category of bacteria).
• Mouth: Your teeth, tongue, cheek, lips, and palate provide habitat for mostly harmless or beneficial bacteria. Almost 300 different species have been found in the mouth alone. And those are just the ones that have names so far.
• Ear, Nose, Sinuses, and Throat: Each of these regions contains bacteria that can thrive in that particular environment. But they’re mentioned together because they’re all connected. And they intersect with the mouth, as well.

This is not a comprehensive list of your body’s bacterial communities. They’re in your sex organs, lungs, and about any hospitable place they can find. The gut gets most of the attention, but researchers are looking more closely at other areas. That research will help us get to know our microbiomes better, and help us meet more of our bacterial buddies.

The Making of a Microbiome

You’re shaped by the ecosystem in which you live. Your microbiome is the same. But in this case, you’re the ecosystem.

That’s why everyone’s microbiome is unique. Yours is shaped by the experiences you have—starting at birth. Natural birth or Caesarean section will impact an infant’s microbiome. Your diet and environment impact your body and the bacterial friends that live with you. Age is also an important differentiating factor.

With the array of variables and huge variety of bacteria in your body’s ecosystem, it’s difficult to identify every strain of bacteria “normal” or “healthy” people will have. Mapping out your specific microbiome regularly over time is time consuming and overwhelming. And doing it once doesn’t tell you much. But talking more generally provides the information you need without listing thousands of bacterial strains.

Basically, the bacteria that coexist with you are the ones able to find a biological niche. They’re best able to adapt and survive in your specific conditions. In this way, you’re somewhat in control of your microbiome. And somewhat is the keyword. It’s not as easy as selecting your preferred bacteria, because you can’t control everything. We do know that good habits— sleeping well, exercising, and eating a healthy diet—encourage a beneficial microbiome.

But bacteria are living things. They’re competing with trillions of others for space and food. You can influence the results of this competition, but you can’t totally fix the game. And for those same reasons, your microbiome is constantly changing.

What Can the Microbiome Do for You?

The simple answer—your microbiome does a lot. And research is revealing more and more about what it does for you and your health.

This example tells you quite a bit: Mice raised without a community of bacteria—born and raised in a sterile environment—don’t exhibit the same type of growth as mice with a microbiome. Germ-free mice also show deficiencies in behavior and other health issues not seen in normal mice.

In general, your microbiome helps with digestive processes, immune function, maintaining a healthy weight, nervous system function, and more. But that’s another story. You can dive deeper into the ways your bacterial buddies help out your health in the next article in our microbiome series.