What’s the Difference Between Probiotics, Prebiotics and Postbiotics?

What’s the Difference Between Probiotics, Prebiotics and Postbiotics?

Scientifically reviewed by: Michael A. Smith, MD


While most of us are familiar with antibiotics, not everyone knows exactly what probiotics are. We think of antibiotics as friends to our health, because they reduce or stop the growth of bacteria—but that does not mean all bacteria are enemies! In fact, probiotics are a type of bacteria that can help us stay well.

The difference between these types of bacteria, and those we seek to combat with antibiotics, is that probiotic microorganisms are beneficial to the body, while the organisms we want to treat with antibiotics are, of course, potentially harmful.

Making things even more complicated: there are also prebiotics and postbiotics, and like probiotics, they can aid in digestive health, immune health, and beyond. But they serve different roles within the body, and can come from different sources. Here’s a rundown on how each of these nutrients can impact our wellness.

What are probiotics?

A healthy woman holds her stomach while drinking kefir

Probiotics, which are beneficial bacteria that can be ingested, support gastrointestinal health, including digestion. But, that’s not all they do! We are learning more all the time about how these microorganisms can benefit not only the GI tract, but the entire body, including the brain.

How probiotics benefit your health

Man has a healthy brain

Healthy digestion and a strong immune system may depend on what’s living in your gut—you need to have the right balance of healthy intestinal bacteria, while limiting the overgrowth of potentially harmful bacteria. A healthy diet rich in probiotic-friendly foods helps achieve this amazing balancing act, and certain probiotic strains may also help control the overgrowth of fungi such as Candida albicans.

Your microbiome, or the community of microbes that reside in your gut, also has an impact on cognitive health. It might seem strange that bacteria within your digestive tract would have any influence on your brain, but since the gut and brain communicate through the vagus nerve, endocrine signaling mediators and the immune system, these systems really are connected. For that reason, probiotics are being studied for potential benefits to people with depression, anxiety, autism, and other psychiatric disorders.

One surprising thing that Alzheimer’s and Parkinson’s disease patients have in common is a high incidence of gastrointestinal disorders—and bacteria within the gut is thought to play a role. Why? Overgrowth of unhealthy microflora may mean that the gut barrier is easier to breach. The result? Neurological inflammation and degeneration— hallmarks of both Alzheimer’s and Parkinson’s—may occur.

Whether you want to preserve healthy brain function, promote healthy digestion, or support immune health, eating a balanced diet rich in probiotic-friendly foods is a smart move!

Great sources of probiotics in foods

sauerkraut is a good source of probiotics>

Given their many health benefits, probiotic foods have been used around the world in various forms. For example, kefir, a probiotic-rich drink, has been associated with longevity.

Not so sure about trying this fermented yogurt drink, which when unsweetened tastes quite sour? Any foods that have been fermented are rich in probiotics; other popular options include kimchi, miso, sauerkraut, kombucha, buttermilk, some cheeses and sourdough bread. Of course, the most popular food source of probiotics is yogurt, which may contain multiple probiotic cultures, depending on the variety.

Understanding probiotic species and strains

All probiotic bacteria will be classified by genus, species and strain—meaning that a probiotic will have three words in its name. (The first word in the name may just be a letter, since it’s customary to abbreviate it.)

As for a genus, some common ones include Lactobacillus, Bifidobacterium, and Streptococcus. Each genus can include numerous species, which is the second word in the probiotic name. For example, common Lactobacillus species are acidophilus, casei, plantarum and rhamnosus; better-known Bifidobacterium species include bifidum, lactis and longum.

Following these species names will be the strain, often indicated by a number or letter, as in Lactobacillus acidophilus LA1. Strains are not interchangeable, and it’s important to ensure you are getting the correct strains for maximum benefits!

What is a prebiotic?

Legumes are a good source of prebiotics

Your microbiome is the community of bacteria in your gut—but what fuels the good bacteria? Enter the prebiotic, which is essentially food for those bacteria, giving them the energy they need to flourish. By definition, prebiotics are non-digestible fibers. They become fermented by the bacteria that’s in the gut—a process that promotes growth of more beneficial microorganisms.

You can find prebioticsin many healthy foods, including beans and other legumes, starchy fruits, cereals, onions and other vegetables, as well as milk and fungi. In richly colored, red and purple fruits, which are rich in antioxidants and the nutrient resveratrol, you’ll also find decent sources of prebiotics.

Inulin from chicory is a fructo-oligosaccharide that is a great prebiotic source. Xylooligosaccharides are another good option. Many people focus on both prebiotics and probiotics for optimal health.

What are postbiotics?

fermented foods contain postbiotics

A term that likely is newer to you—because, it’s newer to the entire scientific community—is “postbiotics,” and these are also beneficial to digestive health, immune health and more. While probiotics are the live bacteria, postbiotics are the various materials released by those bacteria. Postbiotics are not live, which is one of their benefits: they have a long shelf life.

Since postbiotics are secreted by bacteria, you’ll find them in fermented foods—many of the same ones that are a good source of probiotics, like sauerkraut and tempeh. Some types of postbiotics include peptides, as well as short-chain fatty acids such as acetate, butyrate and propionate.

As the International Journal of Molecular Sciences concluded, postbiotics may be a good alternative when probiotics are not available. They may be especially valuable for people in underdeveloped nations, where cost and transport of live bacteria may make probiotics impractical.

Be proactive about gut health

Because the bacteria in your gut can help keep you healthy and thriving, you should take every step you can to nurture a thriving microflora environment. For best results, eat balanced meals that include fermented foods and prebiotic sources.