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What are Postbiotics?

What are Postbiotics?

You may have heard of prebiotics and probiotics, but have you heard about postbiotics? Even as a dietitian who feels well versed about the world of the pre- and probiotics, postbiotics was a new term for me. So, let’s dive into this new member of the “biotic” family.

What are Postbiotics?

First, let’s start with a review of the “biotic” terms. Probiotics are beneficial bacteria in the gut. Prebiotics are the fermentable fibers and other compounds that act as food for the probiotics. Postbiotics are bioactive compounds that are produced by probiotics during the fermentation process.1 These compounds include by-products of fermentation such as short chain fats, proteins, beneficial carbohydrates, and inactivated microbes. 

Emerging research suggests that these byproducts may have some potential health benefits. They may also hold certain advantages over probiotics in that they are not alive and therefore are completely shelf-stable. Postbiotics can also be used by those that are immunocompromised and unable to take probiotics. Although all of this is relatively new science, it is still interesting to offer a different alternative to probiotics. 

Benefits of Postbiotics

The bioactive compounds in postbiotics are mostly of interest because of their ability to improve immune health. They do this by helping support the health of the bacteria that already exist in the gut, keeping beneficial populations in balance and the immune system in check.

Although further research is needed, postbiotics may be beneficial in helping improve and restore bacterial imbalances that lead to the development of various digestive illnesses. The focus so far has been on postbiotics of inactivated lactobacilli which seem to have positive effects on the treatment of IBS and diarrhea.2 

Postbiotics may offer some benefit to the formula fed infant. One of the many benefits of breast milk is the transfer of the mother’s immunity to the infant. This is partially accomplished through the ingestion of a prebiotic found only in human milk. Adding both pre- and postbiotics to baby formula may help mimic this benefit without giving infants live bacteria that could overwhelm their delicate immune systems.

Postbiotics may also increase the nutrient density in foods. For example, they may be able to convert certain fats into healthier versions or increase the bioavailability of B-vitamins or vitamin K. 

Additionally, postbiotics are currently under investigation for other benefits such as helping manage inflammation, weight, blood pressure, and cholesterol, as well as the potential for acting as an antioxidant.4

Where to Find Postbiotics

Postbiotics, since they are a byproduct of fermentation, are most commonly found in fermented foods. Common sources include:

  • Yogurt with live active cultures
  • Kefir
  • Kombucha
  • Sauerkraut
  • Tempeh
  • Fermented vegetables

Before you increase your intake of all of these fermented foods, there are a few downsides to postbiotics. Histamine, a common postbiotic, can make IBS or other digestive issues worse. Some people may also experience an increase in gas and bloating with the addition of fermented foods to their diet. If you have never tried fermented foods, start slowly and monitor how you feel before adding more. 

Although this emerging science is interesting, the bottom line that for most people eating fermented foods is likely beneficial for gut health and immunity. So pick your favorite fermented option and add it to your diet regularly. 

Yours in Health-

Ana Reisdorf, MS, RD

IVL’s Community Registered Dietitian


  1. Wegh CAM, Geerlings SY, Knol J, Roeselers G, Belzer C. Postbiotics and Their Potential Applications in Early Life Nutrition and Beyond. Int J Mol Sci. 2019;20(19). doi:10.3390/ijms20194673
  2. Tsilingiri K, Barbosa T, Penna G, et al. Probiotic and postbiotic activity in health and disease: comparison on a novel polarised ex-vivo organ culture model. Gut. 2012;61(7):1007-1015.
  3. Szajewska H, Skórka A, Pieścik-Lech M. Fermented infant formulas without live bacteria: a systematic review. Eur J Pediatr. 2015;174(11):1413-1420.
  4. Aguilar-Toalá JE, Garcia-Varela R, Garcia HS, et al. Postbiotics: An evolving term within the functional foods field. Trends Food Sci Technol. 2018;75:105-114.