Home Gut Microbiome Probiotics vs. Prebiotics

Probiotics vs. Prebiotics

by previlli

Over 500 species of bacteria

While probiotics have many important functions, they aren’t the most efficient at shifting the balance of who lives in our gut in favor of the good guys. If we really want to change the microbiota or who lives in our gut, then we need to feed them differently. Prebiotics are the healthiest food source for our gut bacteria.  Studies show that diet has the most profound impact on the profile of our microbiota.  When we eat junk, we feed the sugar-loving, lazy metabolizers in our gut, and we encourage them to eat more and invite their friends.  These naughty bacteria in turn send signals to our brain to eat more sugar and store more energy (fat). 


When we eat fruits and vegetables rich in prebiotic fibers and polyphenols, we encourage the fiber-loving, industrious metabolizers.  These healthy bacteria produce short chain fatty acids that burn energy and send signals to our brain that we are full.  BTW: They also like to invite their friends. 

How can we tell the difference between probiotics and prebiotics?  How can we get more of the power of prebiotics in our diet?

What are they?

Beneficial live bacteria (1)

Not live organisms, but plant-derived indigestible components, like some types of fiber and polyphenols, that feed the beneficial bacteria already in the gut. (2)

The gut hosts over 500 species of bacteria. (1) The most commonly used probiotics are strains of three main species: Bifidobacteria, Lactobacillus and Saccharomyces. Collectively, the bacteria and genetic expression in the gut is called the microbiome. (2)  However, commercially available probiotics are not necessarily the ones  indigenous to the gut.

Prebiotics are indigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of bacteria in the colon to the benefit of the host.  The most commonly used prebiotics are high-dose fibers like fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), and trans-galacto-oligosaccharides. (3)  New science has discovered non-carbohydrate prebiotics in superfoods, like polyphenols.


What forms do they come in?

Probiotics are found in many fermented foods. Bacteria are left in the final products. (4) Here are some examples: yogurt, kefir, sauerkraut, pickles, kimchi, tempeh, kombucha, probiotic supplements.

Prebiotics and polyphenols are found in many fruits and vegetables, containing complex carbohydrates, ones the body can’t digest. (5) Complex carbohydrates come in many forms, but you can find them here:  cereal, whole grains, fruit, vegetables, nuts, legumes, flaxseed, prebiotic/fiber supplements. 

Where do they live?

Probiotics are sensitive to their environment.  High temperatures and stomach acid may kill active bacteria. (6)  Probiotics need to be specially encapsulated to survive the stomach and remain viable.

Prebiotics are usually resilient to high temperatures and stomach acid. (7)  Prebiotics make it through the small intestine to be fermented by the bacteria of the large intestine.

How do they function?

Probiotics are not known to permanently colonize the digestive track.  They have a transient impact by interacting with the host bacteria. Probiotics can’t do their best work without prebiotics to provide a healthy snack for them.


  • Stimulate indigenous organisms
  • Supply metabolites / Cross-feeding
  • Produce growth factors
  • Activate anti-inflammatory pathways
  • Block pathogenic bacteria (8)
  • Communicate and modulate immune system (11)
  • Strengthen gut barrier function (13)


Prebiotics are indigestible components that go through your stomach and small intestine to land in your large intestine, where most of your microbiota live.  The microbiota then break down these components through a process called fermentation.


  • Shift the microbiota in favor of good bacteria (8)
  • Prebiotics increase the diversity of organisms in the gut
  • Supply metabolites / Cross-feeding
  • Stimulate growth factors
  • Increase short-chain fatty acid production (9)
  • Improve mineral absorption (14)
  • Modulate the immune system (12)
  • Strengthen gut barrier function
  1. https://doi.org/10.1016/j.cgh.2012.03.024 
  2. https://doi.org/10.1038/s41575-019-0173-3
  3. https://doi.org/10.3390/foods8030092
  4. https://www.webmd.com/digestive-disorders/ss/slideshow-probiotics
  5. https://doi.org/10.1080/19490976.2017.1290756
  6. https://doi.org/10.3390/nu11071591
  7. https://doi.org/10.3390/nu9091021
  8. https://doi.org/10.1007/s13197-015-1921-1
  9. https://doi.org/10.3390/foods8030092
  10. https://doi.org/10.1016/j.anaerobe.2013.09.012
  11. https://doi.org/10.1159/000496426
  12. https://doi.org/10.1080/1040841X.2016.1211088
  13. https://doi.org/10.1111/j.1440-1746.2008.05685.x
  14. https://doi.org/10.1093/ajcn.82.2.471 
  15. https://doi.org/10.1002/jcph.1121
  16. https://doi.org/10.1111/jgh.13700
  17. https://doi.org/10.3390/nu11030635
  18. https://doi.org/10.3945/jn.112.166132
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