Probiotics, prebiotics, and postbiotics keep your dog healthy in so many ways we’re still learning about. One especially exciting discovery is that postbiotics may be the true superpower in fermented foods.

You’ve heard plenty about probiotics (like the Lactobacillus acidophilus bacteria in yogurt). You probably even know about prebiotics (the little fibers that microbes eat, like the inulin found in Jerusalem artichokes). But what exactly are postbiotics? When microorganisms (like beneficial gut bacteria) digest the substances they use as fuel (prebiotics), they produce all sorts of chemical compounds. And when those compounds themselves have health-promoting properties, they’re called postbiotics.

It’s a relatively new term that’s been popping up a lot lately, both in new commercial products and in the scientific literature, but “postbiotics” wasn’t an officially defined concept until very recently. In 2019, the International Scientific Association for Probiotics and Prebiotics (ISAPP) convened a panel to establish a definition and to review the existing evidence of postbiotics’ beneficial health effects.

According to the ISAPP panel’s consensus statement, published earlier this year, postbiotics are inanimate microorganisms or components of microorganisms that confer a health benefit on their host. In other words, unlike probiotics, postbiotics are not alive. They may be chemical compounds or dead microbial cells or parts of cells. They are safe. And they contribute to observed health benefits that have been confirmed through clinical trials.

The exciting part is that we’re learning a lot about exactly how postbiotics promote health—in people and in pets. Here are just a few things that postbiotics do:

• Help the digestive tract absorb nutrients
• Reduce inflammation
• Prevent leaky gut syndrome
• Boost the immune system
• Support healthy skin
• Protect against food allergens
• Lower blood sugar
• Increase insulin sensitivity
• Prevent diabetes

How Did We Get from Probiotics to Prebiotics to Postbiotics?

What we’re learning now about postbiotics and their role in the healthy functions of humans and animals is a direct result of scientists’ growing understanding of the gut microbiome. Here’s how we got from probiotics to prebiotics to postbiotics.

When scientists began studying the gut microbiome, they learned that certain kinds of bacteria are really important for our overall health: this is where the term probiotic (meaning “promoting life”) comes from.

Probiotics are live microorganisms that have health benefits when consumed in the right quantity. Humans have been deliberately consuming probiotic organisms at least since the invention of cheese, more than 7,000 years ago. So lactic acid bacteria (a large family called Lactobacillaceae), used to ferment milk, were probably the first probiotics that humans harnessed for their beneficial properties.

By the first decade of the 20th century, scientists were proposing that probiotic bacteria could be used to change the microbial composition of the gut and thereby improve the health of the digestive system. Since then, numerous clinical studies in humans and in all kinds of animals have shown that the consumption of both natural probiotics (like those found in fermented foods) and dietary supplements containing probiotics is associated with significant improvements in many health conditions known to be related to the gut microbiome.

As scientific knowledge about probiotics grew, researchers realized that beneficial bacteria survive and function better if they are fed the right foods. This is where the term prebiotics comes from.

The most common prebiotics are plant-based fibers and “resistant starches,” like inulin, mannan-oligosaccharides (MOS), and fructo-oligosaccharides (FOS). These little soluble fibers are ideal forms of fuel for the beneficial bacteria that live in your gut—and also in your dog’s gut.

When bacteria and other microorganisms digest prebiotics, they release a wide variety of compounds that also have important beneficial functions in the body. These compounds are often called metabolites because they are products of metabolism—in this case, the microorganisms’ digestion of their food. Since they come “after” the digestion of prebiotics, these compounds are called postbiotics. They include a variety of peptides, enzymes, amino acids, vitamins, neurotransmitters, cell wall components, and many other molecules that the body needs.

Researchers are discovering that postbiotics promote health in a huge number of different ways. Postbiotics are especially important for fueling the processes performed by the cells lining the colon, including immune cells. (About 70%–80% of the body’s immune cells live in the gut.)

In fact, it turns out that those benefits of probiotics that we knew about hundreds of years ago were not actually related to the bacteria themselves, but to the compounds they create—the postbiotics. So a big reason foods like yogurt, kefir, sauerkraut, and miso are so good for you (and, in small amounts, for your dog too) is that, through the fermentation process, the live bacteria in those foods produce nutrients and other compounds (like enzymes, vitamins, and short-chain fatty acids) that play important roles in digestion, immune cell production, nervous system function, and multiple other aspects of the body’s health.

We know that probiotics, prebiotics, and postbiotics all have important roles to play in your dog’s digestion and overall wellness. But how do you know whether your dog is getting enough of all three? And if your dog is having distressing symptoms—like diarrhea, constipation, bloating, or itchy skin—or suffers from a chronic condition like inflammatory bowel disease (IBD), how do you know whether you should give your dog more probiotics, prebiotics, or postbiotics?

A Gut Health Test is the best way to find out the status of your dog’s microbiome. By analyzing a small sample of your dog’s poop, our scientists can identify all the different kinds of bacteria living in your dog’s gut, flag any imbalances that might be causing trouble, and let you know if any important bacterial groups are missing. The test includes a report with personalized recommendations for diet changes and supplementation, so you’ll know exactly how to improve your dog’s health and whether a pro-, pre-, or postbiotic supplement is right for your pet. Learn more about testing your dog’s gut health here.

For example, too big a population of Prevotella bacteria in the gut is associated with unhealthy inflammation and probably means your dog’s diet is too high in carbohydrates. Transitioning to higher-protein foods and adding a prebiotic supplement (like inulin, MOS, or FOS) can help increase the numbers of other beneficial gut bacteria, like Fusobacterium, and restore the kind of balance we see in healthy dogs.

Pet food producers are very aware of the benefits of probiotics for dogs. Maybe you’re already feeding a dry or canned food that claims to be rich in “healthy microflora” or to contain the “best probiotics for dogs.” That’s good, right? Unfortunately, no: unless they are  spore-forming bacteria (such as Bacillus coagulans), those probiotics are most likely dead and unable to do your dog much good.

Probiotic strains are difficult to incorporate into commercial pet food because they’re live organisms, and they typically don’t survive the processing that these products undergo. Both kibble and canned food are subjected to high temperatures, which kill most beneficial microorganisms. And adding a probiotic coating after processing doesn’t really solve the problem, because coatings don’t adhere evenly, and probiotics also don’t survive long storage.

So even if the label says a dog food contains probiotics, those beneficial microorganisms might not actually be alive, and probiotics have to be viable to be effective.

Postbiotics, on the other hand, are not living organisms: they’re just nutrients. They can be stored for a long time without losing their healthy properties, and they won’t compete with the resident microbes in your dog’s gut.

Since commercial dog foods aren’t a good source for most probiotics, supplements tend to be a better option. Among probiotic supplements for dogs, we often recommend Saccharomyces boulardii, which is actually a probiotic yeast. S. boulardii is especially helpful for diarrhea, and because it’s a yeast, it’s not killed by antibiotics, so it can be given during antibiotic treatment. S. boulardii is one of the main ingredients of Gut Maintenance Plus, which also contains prebiotics and is designed specifically to help with diarrhea caused by antibiotics or E. coli infection.

Including small amounts of fermented foods in your dog’s diet is a great way to add both probiotics and postbiotics. If your dog is lactose-intolerant—meaning that they don’t have enough of the enzyme needed to digest lactose (the form of sugar found in dairy products)—then unsalted sauerkraut is a better choice than yogurt or kefir. (More on the power of fermented foods later.) And as always when you give your dog any kind of human food, be careful to avoid artificial sweeteners, which can be toxic to animals.

Our DoggyBiome™ ImmuneShield™ is a new postbiotic chew for dogs. The active ingredient is EpiCor® Fermentate, a postbiotic formulation based on another yeast, Saccharomyces cerevisiae. ImmuneShield supports a dog’s immune system, helps the body produce more immune cells, and reduces systemic inflammation. These tasty soft chews can help with uncomfortable skin issues as well as gastrointestinal symptoms.

EpiCor is made by putting S. cerevisiae through a fermentation process that produces a unique collection of postbiotics: specific proteins, polyphenols, vitamins, minerals, amino acids, polysaccharides, fiber, and other nutrients. Multiple human studies have shown that EpiCor improves constipation and GI discomfort and promotes positive microbiome composition changes in people with various digestive issues.

In studies of dogs, EpiCor has also been shown to promote healthy immune response. One study in particular found that the S. cerevisiae fermentation product in EpiCor has “positive effects on gut health and immune function in dogs,” in part because it increases Bifidobacterium and decreases Fusobacterium. The study concluded that this product “may be used in dog food to improve gut health by shifting gut microbiota positively, elevating immune capacity, and decreasing inflammation.”

Postbiotics—the beneficial byproducts of particular species of microbes (both probiotics and resident gut bacteria)—have far-reaching effects on digestion, proper immune system function, and overall health.

• Postbiotics affect the gut microbiome. Some postbiotics serve as food for particular resident gut microbes. Other postbiotics carry lactic acid. When certain microbes consume lactic acid, they produce short-chain fatty acids and butyrate, two substances known to play multiple beneficial roles in digestive health. (Butyrate has been found to help lower both blood pressure and cholesterol.)
• Postbiotics improve the functioning of the gut lining. The lining of the gut protects against disease by preventing pathogens and other harmful microbes from passing from the colon into the bloodstream. Postbiotics support this barrier function both by reducing inflammation and by helping signal the epithelial cells that make up the gut lining to fit tightly together, preventing “leaky gut.”
• Postbiotics influence the immune system. The most well-studied postbiotics are short-chain fatty acids (SCFAs), which have important anti-inflammatory and antioxidant properties and have been associated with immune system function and allergy response. Studies have shown that certain postbiotics increase T-cell response in tuberculosis patients and improve the recovery of cancer patients’ white blood cell counts after chemotherapy.
• Postbiotics influence metabolism. The body’s metabolism—including the conversion of food into energy to fuel cellular processes—is directly influenced by postbiotics. In multiple studies, SCFAs have been correlated with weight control in dogs, obesity in children, insulin sensitivity, and diabetes.

Bacteria “eat” prebiotics—and produce postbiotics—through fermentation, which is basically a metabolic process that extracts energy from carbohydrates. That means that fermented foods, like yogurt, kefir, and sauerkraut contain not only probiotics but also a lot of postbiotics. And it turns out that the postbiotics—the nutrients produced by the live microorganisms—may be the real reason fermented foods are so good for us.

Humans have been eating fermented foods for thousands of years, and we’ve known for a long time that these foods offer significant health benefits. Now, thanks to a recent study from Stanford University, we know a lot more about why fermented foods are so healthy. This study found two main health-promoting effects of a diet rich in fermented foods: increased gut microbiome diversity and decreased inflammation.

• More microbial diversity. Consuming fermented foods leads to a more diverse gut microbiome. In fact, the study found that the more fermented foods eaten, the higher the number of microbial species in the gut. In both humans and animals, greater diversity in the gut microbiome is associated with lower rates of chronic disease and better health overall.
• Less inflammation. The study also found that fermented foods are associated with a reduction in inflammatory activity throughout the body. Specifically, the researchers found reductions in 19 inflammatory compounds, including interleukin-6, an inflammatory protein that tends to be elevated in Type 2 diabetes and rheumatoid arthritis.

Thanks to all those amazing postbiotics, fermented foods can boost your dog’s health in multiple ways. Adding a little unflavored yogurt or unsalted sauerkraut to your dog’s diet is a great first step toward better digestion, a stronger immune system, healthier skin, and even a happier mood.

• Postbiotics are beneficial chemical compounds produced when microorganisms—like probiotics and resident gut microbes—digest their food (prebiotics).
• DoggyBiome ImmuneShield is a postbiotic chew that can help with both gastrointestinal symptoms and skin issues.
• Postbiotics promote good health in multiple ways—including boosting the immune system, improving the functions of the gut lining, promoting diversity in the gut microbiome, reducing inflammation, maintaining healthy skin, and lowering blood sugar.
• The real reason fermented foods (like yogurt and sauerkraut) are so healthy is that they contain both probiotics and postbiotics.
• A Gut Health Test can tell you whether your dog’s diet is promoting a healthy gut.
• Your dog can’t get enough live probiotics from a commercial pet food, because most probiotics don’t survive the processing that kibble and canned foods undergo.