The human body is full of bacteria. Believe it or not—this is a good thing. Living microbial communities play a vital role in human health. These “microbiomes” can be found in the gut, the skin, the mouth, the respiratory tract, and more.

Over the past couple decades, scientists have made numerous discoveries about how the microbiome works and the many ways it benefits health. Most of this work focused on the intestine, but research suggests that some of the knowledge we’ve gained could benefit other microbiomes in the body.

Probiotics, living microorganisms that benefit gut health, emerged from the initial scientific discoveries about the microbiome and quickly became one of the most popular supplements consumed in the world. As the science developed, the focus broadened to include prebiotics, the variety of fibers that act as gut microbiome fertilizer.

Recently, a new biotechnology has started to hit the shelves: postbiotics.

In this article, we’ll discuss everything you need to know about these beneficial byproducts.

What are Postbiotics?

Postbiotics are the byproducts of the natural metabolic process (fermentation) of probiotic bacteria. They include various types of molecules such as short-chain fatty acids, peptides, organic acids, enzymes, and more. They offer many of the same benefits that probiotics do. But there’s one key difference. Postbiotics are non-living bioactive metabolites. While probiotics are live strains of bacteria.

There are three similar words that frequently come up when discussing the microbiome, each with its own unique definition: probiotics, prebiotics, and postbiotics. Let’s clarify the difference between each term:

• Probiotics: Unlike the following two terms, probiotics are living microorganisms. Basically, they’re the “good” microbes living in your gut. You can bring more probiotics into your body by eating probiotic foods such as yogurt, kefir, sauerkraut, and kimchi—or quality probiotic supplements.
• Prebiotics: Like all living things, your microbes need to eat. Prebiotics are the substances that the microbes in your body consume for sustenance. These include starches, inulin, and pectin—all forms of complex carbohydrates.
• Postbiotics: When probiotic bacteria metabolize their food, they create various byproducts. These byproducts can offer you some of the same benefits as the microbes themselves and are called postbiotics.

Postbiotics don’t require the use of live bacteria. They’re stable, safe, and have a broad range of application in health products. You might start to notice them in nutraceuticals, foods, supplements, and even high-end skincare products.

Let’s dive a little deeper into some of the practical applications of postbiotics.

The Gut Biome: A Vital Microbial Ecosystem

One of the most well-researched healthy bacterial communities is the gut biome. When your gut microbiome is healthy, it helps your body digest food, regulate immune function, guard against harmful pathogens, and support cognitive functions through the gut-brain axis. Although the exact composition of each person’s gut biome is different, they are all composed of the same types of microorganisms: bacteria, viruses, and fungi.

When people talk about a functioning microbiome, they often use descriptors like “healthy” and “balanced.” So, what does it actually mean for your microbiome to be healthy? A healthy gut biome is one in which there are plenty of the good microorganisms and inconsequential amounts of the bad. This is exactly how probiotics work. They improve gut health by increasing the number of beneficial bacteria and reducing the number of harmful bacteria to make your microbiome healthier.

Basically, a healthy or balanced microbiome is able to do its job—and if it’s not, you’ll probably notice.

An unbalanced gut biome is called dysbiosis and can have a number of adverse health effects. These include irritable bowel syndrome (IBS), autoimmune disorders, and even new allergies.

Needless to say, it’s important to care for your gut biome.

Postbiotics do many of the same things as probiotics—without live strains of bacteria. They support the growth and the function of healthy bacteria in your gut microbiome, which supports your health. This means that postbiotics shift the composition of the microbiome towards a healthier, more balanced ecosystem. Postbiotic metabolites also have direct benefits for the gut. They’ve been shown to:

• Regulate digestion and absorption of nutrients
• Support the intestinal barrier
• Suppress bad bacteria
• Fight pathogens
• Play a role in the gut-brain axis
• Reduce irritation in the gut

So how do you increase the amount of postbiotics in your gut? Like with all things health-related—it starts with your diet.

Dietary Sources of Prebiotics, Probiotics, and Postbiotics

Your body naturally produces postbiotics as the bacteria in your gut metabolize their food and create waste. You can increase the amount of postbiotics in your system by increasing the amount of probiotics and prebiotics that you consume. The formula is pretty simple: the more food (prebiotics) you supply to the microorganisms (probiotics) in your gut biome, the more byproducts (postbiotics) they will create.

Foods that are rich in probiotics are typically fermented foods, which include:

• Kefir
• Cottage cheese
• Kimchi
• Kombucha
• Buttermilk
• Sauerkraut

High fiber foods tend to be the best source of prebiotics. Some examples of prebiotic-rich foods include:

• Barley
• Garlic
• Oats
• Seaweed
• Flax seed
• Onions

If you are looking to directly supply your body with more postbiotics, those supplements exist as well. But some of the most interesting applications for postbiotics are those that wouldn’t be practical for probiotic bacteria.

Let’s discuss how the benefits of postbiotics translate to another important microbiome: your skin flora.

Skin Microbiome: Your Body’s Natural Barrier

The skin microbiome is the community of microorganisms; bacteria, fungi, and viruses, that live on the skin. Just like the gut microbiome, this microbial community is much more than a passive, fellow traveler. The skin flora plays a vital role in maintaining skin health and even other aspects of health. Here are some of the roles your skin microbiome is involved in:

• Protection of the Skin: A healthy skin flora inhibits the growth of potential invaders and pathogens on the skin.
• Skin Barrier Function: Your skin microbiome acts as a functional barrier, helping the skin retain moisture, improve hydration, and reduce skin sensitivity.
• Immune Support: The skin flora interacts with the immune system to support balanced inflammatory responses.
• Tissue Healing: A balanced skin microbiome promotes tissue repair and cell turnover on the skin while preventing infection in vulnerable areas.
• Skin Health and Beauty: A strong and healthy skin flora is associated with a balanced complexion and clear, moisturized skin.

Dysbiosis occurs when the skin microbiome is out of balance or disrupted. This can lead to a variety of skin issues like acne, redness, dermatitis, and infections. In fact, skin sensitivity and problematic skin are related to a damaged skin microbiome.

Maintaining a healthy skin flora involves taking care of your skin, avoiding harsh chemicals in skincare products, and choosing products that support a healthy microbial balance on the skin.

That’s where postbiotics come in.

Postbiotics can support the good bacteria on the skin by feeding it with beneficial metabolites. That’s why many skincare products now include postbiotics. Using postbiotics on the skin will support all the benefits we mentioned above. They can improve the skin’s barrier function, reduce acne and skin sensitivity, improve hydration, balance the pH of the skin, and even reduce signs of aging like visible fine lines and discoloration.

In Summary

Science has discovered so much in recent years about the symbiotic microbial communities in the human body. But we are still barely scratching the surface.

Although much of the research has been focused on the gut microbiome, the biotechnology of postbiotics represents a new frontier. Where the discoveries made about the gut microbiome can be applied in completely new contexts.

The years to come will undoubtedly lead to more discoveries and a better understanding of the body’s less-explored microbiomes in overall health.

You’re a gardener—even if you don’t have the green thumb to prove it. You may never have planted a seed and cared for it until it sprouts from the earth. But you’re still a gardener of sorts. That’s because your gut is like a garden and your diet acts as the soil and fertilizer.

What you put into your garden influences your microbiota (the microbes that grow there). Specifically, the mix of fiber, protein, carbohydrates, fat, and micronutrients in your diet determines whether your microbiome will flourish.

The microscopic residents of your gut include fungi, viruses, yeast, and other microorganisms. But bacteria are the most notable gut flora. Because their lifespan is short, bacteria can adapt to environmental changes rapidly. They can also take genetic material from neighboring gut flora, which can benefit both bacteria and the host they live in (you!).

These characteristics are what make bacteria so impactful on human health. And that’s why it’s important to understand how your diet cultivates the health and diversity of bacteria and other gut flora.

How Your Gut Garden Started

You weren’t born with the bacteria you now have in your gut. This profile was built over the initial years of your life, starting with the way you were born. Cesarean versus vaginal delivery dictated the initial dominant bacteria in your gut. Then, what you were fed rounded out your gut’s early bacterial profile.

Studies on mother’s milk really illustrated the role and importance of gut microbiota. Researchers initially were unsure why the milk contained such complex carbohydrates. These molecules were known to be indigestible for infants. The babies lacked the necessary enzymes. However, early research revealed the complex carbohydrates are actually present in mother’s milk to nourish the infant’s gut microbiota, and not the infant.

So, your gut garden began at this early stage in life. Mother’s milk acted as the rich soil that nourishes bacteria within. The result was symbiotic for the bacteria and baby. The bacteria flourished, and in doing so, protected the baby’s gut lining. This was important for healthy immunity and nutrient absorption—and remains important as an adult. Proliferation of good bacteria meant they can crowd out possible pathogens and break down the complex carbohydrates into digestible parts.

After your first two years of life, your microbiome’s profile was nearly set. And even with all the variety in flora, lifestyle, genetics, and anatomy, there are some bacteria typically found in the gut microflora.

The most common types of bacteria found in the human gut belong to the phyla firmicutes and bacteroidetes, actinobacteria, and proteobacteria. These phyla (a biological classification) contain bacterial species you may have heard of before, like Lactobacillus, Prevotella, Bifidobacteria, and H. pylori.

There has been a concerted effort to extensively analyze the human microbiome. More research needs to be done before one profile is proclaimed the healthiest. But even with a lack of definitive answers, an educated conclusion can still be made.

One confirmed characteristic of a healthy gut is a diversity of microflora. Diverse bacterial communities tend to be more resilient. This means they’re better at fending off potential pathogens that might invade and try to take over space. When the gut microbiota is filled with a plethora of various good bacteria, the bad kind don’t have empty space to take up residence.

This is a constant battle for space and resources. And you play a big role. As the gardener, you control the soil and fertilizer, which determines what grows best. That’s where what you choose to eat comes into play.

How Your Diet Affects Your Gut Microbiome

Research shows differences in microbial profile exist based on the content of your current diet—just like the differences explained by feeding mother’s milk versus formula. That means a diet rich in fruits and vegetables (which contains more fiber) will produce a different bacterial profile than one rich in animal protein and fat, or another full of simple and processed carbohydrates.

But what kind of dietary soil grows the most diverse and robust gut-flora garden? And which diets fail to yield advantageous bacterial profiles?

The table below will give you an idea of how gut microbiota shifts with different diets. You don’t need to be an expert on the different bacteria listed below to get an idea of that key characteristic of a healthy gut—diversity.

 Western Diet

This type of diet is high in saturated fat and sugar, and it features processed foods. Because it lacks a variety of fruits and vegetables, the modern Western diet lacks fiber. If you remember from earlier, fiber is what feeds your gut microbiota. That’s why fiber is often called a “prebiotic.” That’s because it feeds the bacteria that ultimately help nourish you.

Without that fiber, there are fewer species of flora in your gut that can thrive. This means microbial diversity is less than with other diets rich in fiber from fruits, vegetables, and whole grains. Decreased microbial diversity leads to decreased gut resilience, which can spell problems for your health.

Mediterranean Diet

On the other hand, the Mediterranean diet is known for healthy variety. That includes:

• Various fruits and vegetables
• The inclusion of legumes and whole grains
• A generous use of healthy fats—like olive oil
• Minimal intake of animal-based proteins

This mix creates a diet rich in fiber—or prebiotic material—that your gut microbiota literally lives for. And, as you might have guessed, the Mediterranean diet promotes microbial diversity. One review of diet-induced microbial changes noted no decreasing species in those who consumed a Mediterranean diet. On the other hand, researchers noticed an uptick in at least three species.

Not convinced? One study focused on a group of Italian participants who ate a Mediterranean diet. Over the course of three weeks, the participants provided three samples that were pooled and analyzed for gut microbial content. The researchers found those who best adhered to the diet had more diverse flora in their guts. More specifically, in plant-based eaters (no animal-based protein), they found an increase in Prevotella bacteria.

Vegetarian

Eating vegetarian yields increases in similar bacteria found in adherents of the Mediterranean diet. Additionally, vegetarian diets also cause an uptick in diversity of microbiota, thanks to all that vegetable-based fiber.

Another notable shift is the decrease in Bacteroides species—the opposite trend seen in Western diets. The main difference is the consumption of animal-based protein. Bacteroides are not inherently bad, and can have a beneficial relationship with the gut. But, should they escape that environment through the gut lining, they can cause issues.

You (And Your Gut Microbiota) Are What You Eat

There’s still much research to be done on the gut microbiome and all of its intricacies. But some things are very clear.

First, you gut microbiota’s health is inherently tied to your overall health. One of the main reasons? Your gut flora help digest food and nourish your body. They also play a role in signaling the brain with various messages, like when we’re hungry or adequately satiated. And flora also play a role in maintaining healthy immunity.

Second, it’s established that you should strive for diversity of microbiota in your gut. And before you worry, there’s no need to completely overhaul your diet to achieve this goal. Instead, start by thinking about ways you can incorporate more fiber into your diet.

Luckily, you have a lot of options for doing so. Try a few of these easy options:

1. Make small, easily applied changes. Like swapping out rolled oats for steel-cut oatmeal. Or eating whole-wheat pasta al dente versus cooked soft. Feeding yourself whole grains that take a little more effort to digest means you’re giving your microbiota more fiber to chew through.
2. Consider replacing a processed snack with fruits or vegetables. And you can make it fun! Apples or carrots can be more exciting when paired with your favorite nut butter. A salad also tastes brighter with fresh strawberries.
3. Skip the peeler when you can. Vegetable and fruit skin (or peels) can have a lot of healthy fiber and nutrients. When you peel them away, you miss the nourishment they provide you and your microbiota.
4. Take a wholly different approach to grains. Love white bread and other grains? You’re not alone. But substituting a serving here or there for a whole-grain option is a good start. Try a multigrain bread, whole-grain pasta, or a new grain altogether (bulgur, quinoa, farro, or brown rice). It can spice up your cooking routine and help your gut.

Lastly, consider easing up on antibacterial soaps and ideology. You want to keep pathogens away from your homes and bodies. But it’s easy to go overboard when it comes to cleanliness. This might mean not washing your hands after petting your dog, or making sure you really need antibiotics before taking them. The common cold is caused by a virus, so you won’t benefit from antibiotics.

The state (and diversity) of your gut microbiota is fairly stable in adulthood, but that’s not the case when you take antibiotics. They can wipe out bad and good bacteria. That’s like depleting a garden of all its organic material, richness, and nutrients at once. And that wonderful, fertile microbial soil will need to be rebuilt. One study found that it can take up to four weeks for your gut microbiota to return to its normal diversity.

Now that you’re in the know when it comes to your microbiota, you can trust yourself to be a master gut gardener. Whether your soil isn’t where you want it to be or not, you have the knowledge and tools to make changes and grow a healthy gut microbiota garden that can benefit your health.

About the Author

Jenna Templeton is a health educator and freelance science writer living in Salt Lake City, Utah. After receiving a bachelor of science degree in chemistry from Virginia Tech, Jenna spent five years as a research scientist in the nutritional industry. This work fueled her interest in personal wellness, leading her to pursue a graduate degree in Health Promotion & Education from the University of Utah. Outside of work, Jenna enjoys live music, gardening, all things food, and playing in the Wasatch mountains.