‘Biotics…What’s in the Name?

Fermented foods, fiber, probiotics, and prebiotics are foods and terms that often come to mind when it comes to microbiome gut health. But now a more recent term is making the rounds, called postbiotics. Then add synbiotics into the mix and these terms can get confusing, not to mention tongue-twisters. Prebiotics. Probiotics. Postbiotics. Synbiotics. Here’s the breakdown on the terms, their benefits, the foods they are in, and how to maximize your microbiome health.

A Refresher on Microbiome Health

The gut microbiome contains more than 100 trillion microbes, including bacteria, viruses, protozoa, and fungi that line the entire intestinal tract. It plays an important role in the absorption of dietary minerals and synthesizes some essential vitamins and amino acids. It’s our first line of defense against harmful organisms, and it communicates with the immune system, as well as shapes our mood and behavior. That is why feeding our gut with the right foods that have pre, pro and postbiotics may positively affect our physical and emotional health.


Probiotics are good bacteria. They are live microorganisms similar to the ones already living in your gut and may offer health benefits when consumed in adequate amounts. The word probiotic itself is often translated to beneficial for life. It is derived from the Latin word pro meaning for and the Greek word biotic meaning life. Eating fermented foods that contain live and active probiotic cultures such as kefir and other fermented foods, including yogurt and kimchi, can help support the microbiome by replenishing the good bacteria and balancing the gut. The advantage of choosing probiotic foods over supplements is that the foods, specifically fermented dairy, have been found to buffer stomach acid, protecting the probiotics and increasing the chance of them making their way through the digestive tract and allowing them a chance to take hold. Probiotics found in kefir have been found to have offer immune support, keep inflammation at bay may aid in digestion, keep harmful microorganisms in check with its antimicrobial properties and microbiome balance support, and aid in nutrient absorption.


Prebiotics are non-living, non-digestible carbohydrates naturally found in a variety of foods. The body doesn’t digest prebiotics but instead, they help the digestive system by promoting the growth of good bacteria. Probiotics need prebiotics to feed off of to remain actively working at their maximum potential in the digestive system. They work together to make sure the body stays on track and regular. The bacteria in the gut also ferment these fibers into short-chain fatty acids, which play an important role in regulating immunity, and have anti-microbial and anti-inflammatory properties. Prebiotics (oligofructose and inulin) can be found in foods such as onions, garlic, bananas, chicory root, Jerusalem artichokes, and asparagus. Some foods may contain prebiotic fiber as an additive in the form of galactooligosaccharides, fructooligosaccharides, oligofructose, chicory fiber, or inulin.

Postbiotics – A Clear Definition of What They Are and Are Not

A recently published consensus paper by the International Scientific Association of Probiotics and Prebiotics defines a postbiotic as “a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host.“ In simple terms, postbiotics include intact nonliving microbial cells and/or microbial cell fragments and structures (such as cell-wall components or membrane proteins), with or without metabolites synthesized by bacteria. This is clear guidance for the food and supplement industry due to the addition of postbiotics becoming popular. However, this definition is a turnaround from what was previously regarded as postbiotics, as these “dead cells” were often called parabiotics or ghostbiotics. Prior, postbiotics were promoted as all helpful compounds that were produced by bacteria as a result of fermentation, such as peptides found in kefir, or the short-chain fatty acids produced by bacteria feeding on prebiotic fibers in the gut. These beneficial compounds are now to be referred to by name only and not as postbiotics. While kefir does contain postbiotics, as all fermented foods do, we also know that kefir’s peptides produced as a result of fermentation are touted for their antioxidant, antimicrobial and anti-inflammatory properties.


Synbiotics by definition are a mixture comprising of probiotics and prebiotics or substrates, such as short-chain fatty acids that can be utilized by host microorganisms and offers health benefits. Foods that contain both probiotics and prebiotics, or recipes, are perfect examples of synbiotics. Overnight oats made with kefir and chia seeds, or chia seed pudding with kefir are two such examples. Other examples include yogurt with flax seeds and bananas or kimchi stir fry with onions and asparagus. Similarly, buying foods that have both probiotics and prebiotics in them offer that synergistic benefit. Lifeway makes an Organic Whole Milk Grassfed Kefir that offers a good source of prebiotic fiber, along with protein, calcium, and 12 live and active probiotic cultures.

1. Salminen S, Collado MC, Endo A, et al. The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nat Rev Gastroenterol Hepatol. 2021. doi: 10.1038/s41575-021-00440-6.
2. Swanson, K.S., Gibson, G.R., Hutkins, R. et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics. Nat Rev Gastroenterol Hepatol 17, 687–701 (2020).