Postbiotics May Help Protect and Support Health—Here's What They Are and How You Can Get Them

Scientists are enthusiastic about postbiotics thanks to what research has suggested about the compounds' potential health benefits.

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Photo: Getty Images / Design by Jo Imperio

You've likely heard of probiotics, the good microbes—found in some yogurts and fermented foods—that are linked to better digestive health, immune function, sleep, and mood. You may have also heard about prebiotics, non-digestible components—found in foods like asparagus, garlic, onions, and bananas—that stimulate the growth or activity of friendly bacteria in the gut. In other words, prebiotics are food for probiotics.

Now the latest buzz is surrounding postbiotics, and the research on these compounds is incredibly intriguing. Here's a primer on what postbiotics are, what they have to do with prebiotics and probiotics, how they may benefit your health, and how to obtain them.

What are postbiotics?

The technical definition of postbiotics is a "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host." It was a definition agreed upon by a panel of experts put together by the International Scientific Association for Probiotics and Prebiotics (ISAPP) in 2019.

So what exactly does that mean? First let's break down the word itself. "Post" means "after." "Biotic" means "relating to or resulting from living organisms." Together, the terms suggest an "after life." Basically, postbiotics are the byproducts left over after probiotics feed on prebiotics.

In other words, unlike probiotics, postbiotics are not live microorganisms. They include substances called peptides, known to slow the growth of harmful bacteria, as well as short-chain fatty acids, which allow good bacteria to flourish. In this way, postbiotics mimic some of the same benefits as probiotics, but they also offer additional perks.

Postbiotic benefits

The exact mechanism of postbiotics is not fully understood, but researchers of a 2022 study published in the journal Trends in Food Science and Technology think the compounds might promote communication between the gut microbiota (the collection of microorganisms living inside the intestines) and the immune system. For this reason, postbiotics are being looked at as a possible strategy in the prevention or treatment of COVID-19.

In addition to their potential to support immune function and fight infections, postbiotics are thought to help preserve the integrity of the intestinal barrier, reduce inflammation, support blood sugar regulation, and help with conditions that range from allergies and digestive illnesses to chronic diseases and obesity.

Human studies on the benefits of postbiotics have shown outcomes that include the eradication of infections due to Helicobacter pylori (the cause of some ulcers); a reduction of symptoms in people with irritable bowel syndrome (IBS) and chronic unexplained diarrhea; and the ability to counter the negative effects of stress. In one randomized, controlled study of 443 individuals with IBS, those who received a postbiotic experienced a substantial modification in IBS symptoms, including a reduction in abdominal pain or discomfort, as well as improvements in bloating and abnormal bowel habits. An Italian study found that, among patients with recurrent respiratory tract infections, the use of postbiotics led to a significant reduction in the number of acute infectious episodes and use of antibiotics.

However, scientists say that, overall, human research is limited and has generated varying results. One small study from Japan among undergraduate medical students found that, over a five-week period, a postbiotic improved sleep quality in males but not females. Another small study, this one from Israel, found no statistically significant effect of postbiotics on inflammatory or performance responses in soldiers undergoing self-defense training.

Many additional studies involving postbiotics, using a wide variety of postbiotics in various formulations for a number of conditions, are being conducted across the globe. While research on postbiotics is incredibly promising, scientists are still learning about the compounds' uses and outcomes.

Postbiotics pros and cons

There are several reasons why scientists are enthusiastic about postbiotics. First, these compounds are regarded as safer than probiotics for certain groups. These groups include people with weaker immune systems, like those with serious illnesses, or individuals who have recently had surgery. In an immune-compromised state, live probiotic bacteria could potentially cause an infection. In addition, because postbiotics aren't live organisms, they're more stable that probiotics, meaning they have a longer shelf life, can be exposed to higher temperatures, and can be stored and transported more easily.

That said, the authors of a 2020 paper published in the journal Nutrients advise that, "although the use of postbiotics is an attractive strategy for altering the microbiome, further study into its efficacy and safety is warranted." In short, while we will likely see postbiotics used for many things in the near future, the scientific puzzle isn't yet complete.

Postbiotic sources

Currently, the best way to produce postbiotics in your body is to eat more prebiotic foods to feed the microbes in your gut. Again, asparagus, garlic, onions, and bananas are some examples. Other prebiotic-rich foods include chicory root, dandelion greens, Jerusalem artichokes, leeks, barley, oats, cocoa, apples, pulses (beans, lentils, peas, chickpeas), nuts, flaxseed, and seaweed.

Microbes used as probiotics exist naturally in your body. You can also consume some types of probiotics in the form of supplements and in certain foods. Probiotics may be found in non-pasteurized fermented foods, like fermented vegetables, kefir, kombucha, and miso. However, the ISAPP states that "the term 'probiotic' should only be used when there is a demonstrated health benefit conferred by well-defined and characterized live microorganisms." As such, the terms 'fermented food' and 'probiotics' should not be used interchangeably. That is, an unpasteurized fermented food may contain live microbes, but not the type or amount that would meet the distinct probiotic criteria.

Given the emerging research, you may be tempted to skip the middleman and jump directly to the endgame: a postbiotic supplement. But again, there's still a lot we don't know. Postbiotic supplements are much newer than probiotics themselves. There are products on the market that claim to support digestive health and immune function, but research on the payoffs of postbiotic supplements for healthy individuals is limited.

If you have a specific health condition and you're considering a postbiotic supplement, talk with your doctor or health care provider first. They'll likely be familiar with the type and form of postbiotic that has been researched for your condition, as well as how long it should be used and if there are any potential interactions you should be aware of.

Bottom line

Postbiotics is an inspiring area of nutrition research. Scientists are still discovering the many ways these bioactive compounds may be used to protect or support health—from optimizing wellness to disease management. However, there are currently no guidelines about the use of postbiotic supplements for general health, wellness, or disease prevention. For now, your best bet is to produce postbiotics internally, by consuming a nutrient-rich diet that contains prebiotic foods. For specific medical conditions in which postbiotic supplements have been studied, follow the guidance of your personal health care provider.

Cynthia Sass, MPH, RD, is Health's contributing nutrition editor, a New York Times best-selling author, and a private practice performance nutritionist who has consulted for five professional sports teams.

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