women having a probiotic

Pre, Pro, Syn and Postbiotics: Breaking Down the Differences 

Kristina Campbell, MSc

Written by: Kristina Campbell, MSc

Updated: June 24th, 2024

World Microbiome Day is June 27th.  The theme for this year, is “feeding your gut – how diet shapes your microbiome.” An important way to support your gut microbiome is by consuming biotics – a category that includes probiotics, prebiotics, synbiotics and postbiotics. But keeping all the biotics straight and knowing which ones to take can be confusing. 

Here’s a quick explainer of the scientific definitions of the biotic substances and how they can benefit your health – with a few surprising facts along the way! 

What is the Difference Between Prebiotics and Probiotics? 

Probiotics are live microorganisms (tiny living things) that improve certain aspects of your health when taken in adequate amounts (1).  

Furthermore, strains of bacteria in the groups lactobacilli and bifidobacteria are the most common types of probiotics. They are available as dietary supplements in capsules, powders and liquids and can also be found in foods such as certain kinds of yogurt.  

It’s important to note that each probiotic is unique, has a very specific intended purpose, with specific types or strains that can help manage certain conditions.

These may include: 

Prebiotics, on the other hand, are the food that keeps beneficial microbes alive (6). Different types of microbes prefer different types of food – so each prebiotic substance has a few types of microbes that like to feast on it and multiply, thereby bringing you a health benefit.  

The most common prebiotics – fructooligosaccharides, galactooligosaccharides, and inulin – are types of fibre. But other prebiotics, such as polyphenols, are not fibres. 

Watch out for labels that say probiotic or prebiotic when the things inside are not actually tested for their ability to bring you a health benefit. You may have to ask a healthcare professional to figure out whether the substance on the label has some science backing its benefits. 

Can you Take Prebiotics and Probiotics Together? 

Yes, taking probiotics and prebiotics together is the best-case scenario. When you take both, you’re eating the live microbes that bring you health benefits, plus the foods that live microbes need to flourish. Sometimes, the pairing is called a synbiotic. 

There’s a caveat, though – different probiotics prefer different food sources. So, if you take a random probiotic with a prebiotic, the prebiotic may not be giving a boost to the accompanying microbes at all. Research is starting to identify the best probiotic-prebiotic pairings that result in better health benefits (7). 

What are Synbiotics?  

A synbiotic is a combination of substances – essentially, a probiotic plus a prebiotic. But sometimes a synbiotic is a pairing of things that don’t quite qualify as probiotics and prebiotics on their own. So, any live microorganisms plus food for live microorganisms, which give you a health benefit when combined, can be considered a synbiotic (8). 

When Should you Take Prebiotics?  

Prebiotics are found in many common foods. Particularly, they’re found in high amounts in: 

prebiotics, postbiotics

Scientists say you should try to consume about 5 grams of prebiotics per day to adequately nourish the beneficial microbes in your gut so they can support your health (9). 

If you’re taking a prebiotic because you want a certain health benefit, the best course of action is to consume it in supplement form. Some of the benefits shown from taking prebiotics are improved bowel movements, better mineral absorption, and more stable blood sugar (10).  

Further, some recent evidence even suggests that older adults perform better on cognitive tests after consuming doses of prebiotics (11).  

However, the effectiveness of some prebiotics may depend on the microorganisms you already have living in your gut (12).  

How Long do Probiotics Take to Work? 

How a certain probiotic works for you depends on a lot of personal factors. A probiotic’s effect also depends on why you’re taking the probiotics in the first place.  

For example, if you’re taking a probiotic to prevent respiratory illness, you may not notice any difference in your health day-to-day. But if you’re taking the probiotic to improve your bowel movements, you may notice a difference within a few days or weeks. 

Generally speaking, if you’ve been taking a probiotic for four weeks and haven’t yet gotten the benefit you’re looking for, it may be time to try another probiotic product. 

Can You Take Too Many Probiotics? 

Yes, if you take too many probiotics you may experience unwanted gastrointestinal symptoms. 

Typically, probiotics taken in any amount pass right through you and don’t stick around in your gut, even though they may be giving you health benefits (13). So, you probably need a regular dose to maintain whatever benefit you’re looking for. 

Remember, the health benefits are tied to a certain dose of probiotics, so you may not see the benefits if you exceed that dose. A higher amount doesn’t necessarily mean a stronger health effect. So overall when taking probiotics, it’s best to stick to a dose that’s been scientifically tested and shown to have a health effect. 

Can I Take Probiotics While Pregnant? 

Probiotics are commonly taken in pregnancy and studies show they can be beneficial for the fetus. In fact, the World Allergy Organization recommends taking probiotics during pregnancy for people at high risk of having a child with an allergic disease because it may reduce the child’s risk of eczema and asthma (14). In addition, probiotics may reduce the risk of gestational diabetes for the person who’s pregnant (15). However, which probiotics works best for these purposes is not yet certain. 

As for the safety of probiotics in pregnancy, the research shows a slight increased risk of preeclampsia, particularly when the pregnant individual falls into the obese category (16). Researchers need more safety data but be sure a healthcare professional is aware and is monitoring your health closely if you take a probiotic supplement during pregnancy. 

For the most part, pregnant individuals are best advised to get their probiotics from food sources such as yogurt. 

pregnant person eating probiotic yogurt

What are Postbiotics? 

The definition of postbiotics is somewhat contested, but the leading scientists are clear: postbiotics are microorganisms that are deliberately killed, then consumed to give you a health benefit (17). Postbioticsneed to contain part or all the nonliving bacteria and may or may not contain leftover molecules that the microbes created while they were alive. Technically speaking, the microbe-produced molecules by themselves are not considered postbiotics.  

The science on postbiotics is emerging, and so far, postbiotics are not shown to have the broad-ranging health benefits that probiotics have. Yet certain postbiotics are shown to reduce gastrointestinal or respiratory symptoms and improve skin health (18). More benefits may emerge in the future. 

Postbiotics are relatively new to North American consumers, but they have a longer history of use in Japan, where they’re added to many foods and drinks. Postbiotics can be safer and cost less than the equivalent live microorganisms, so you can expect to see more of them in the years ahead as companies continue to innovate. 

To learn more about the gut microbiome, read our frequently asked questions here.  


  1. Hill C, Guarner F, Reid G, Gibson GR, Merenstein DJ, Pot B, Morelli L, Canani RB, Flint HJ, Salminen S, Calder PC, Sanders ME. (2014.) Expert consensus document. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol., 11(8):506-14. doi: 10.1038/nrgastro.2014.66.  
  2. Bustos Fernández LM, Man F, Lasa JS. (2023). Impact of Saccharomyces boulardii CNCM I-745 on Bacterial Overgrowth and Composition of Intestinal Microbiota in Diarrhea-Predominant Irritable Bowel Syndrome Patients: Results of a Randomized Pilot Study. Dig Dis., 41(5):798-809. doi: 10.1159/000528954.  
  3. Minoretti P, Liaño Riera M, Santiago Sáez A, Gómez Serrano M, García Martín Á. (2024). Probiotic Supplementation With Saccharomyces boulardii and Enterococcus faecium Improves Gastric Pain and Bloating in Airline Pilots With Chronic Non-atrophic Gastritis: An Open-Label Study. Cureus, 16(1):e52502. doi: 10.7759/cureus.52502.  
  4. Han Y, Zhou Y, Xu X, Chen S, Zhang S, Jiang N, Liu Z, Zhang J, Luo Z, Zhang X, Hao L, Chen T. (2024). Improvement of Post-Surgery Constipation in Patients with Fractures by Lactobacillus rhamnosus JYLR-127: A Single-Blind Randomized Controlled Trial. Nutrients, 16(10):1505. doi: 10.3390/nu16101505.  
  5. Fu J, Zheng Y, Gao Y, Xu W. (2022). Dietary Fiber Intake and Gut Microbiota in Human Health. Microorganisms, 10(12):2507. doi: 10.3390/microorganisms10122507.  
  6. Gibson GR, Hutkins R, Sanders ME, Prescott SL, Reimer RA, Salminen SJ, Scott K, Stanton C, Swanson KS, Cani PD, Verbeke K, Reid G. (2017). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol., 14(8):491-502. doi: 10.1038/nrgastro.2017.75.  
  7. Gomez Quintero DF, Kok CR, Hutkins R. (2022). The Future of Synbiotics: Rational Formulation and Design. Front Microbiol., 13:919725. doi: 10.3389/fmicb.2022.919725.  
  8. Swanson KS, Gibson GR, Hutkins R, Reimer RA, Reid G, Verbeke K, Scott KP, Holscher HD, Azad MB, Delzenne NM, Sanders ME. (2020). The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics. Nat Rev Gastroenterol Hepatol., 17(11):687-701. doi: 10.1038/s41575-020-0344-2.  
  9. International Scientific Association for Probiotics and Prebiotics. Accessed June 6, 2024. https://isappscience.org/for-consumers/learn/prebiotics/ 
  10. Gibson GR, Hutkins R, Sanders ME, Prescott SL, Reimer RA, Salminen SJ, Scott K, Stanton C, Swanson KS, Cani PD, Verbeke K, Reid G. (2017). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol., 14(8):491-502. doi: 10.1038/nrgastro.2017.75.  
  11.  Ni Lochlainn M, Bowyer RCE, Moll JM, García MP, Wadge S, Baleanu AF, Nessa A, Sheedy A, Akdag G, Hart D, Raffaele G, Seed PT, Murphy C, Harridge SDR, Welch AA, Greig C, Whelan K, Steves CJ. (2024). Effect of gut microbiome modulation on muscle function and cognition: the PROMOTe randomised controlled trial. Nat Commun., 15(1):1859. doi: 10.1038/s41467-024-46116-y.  
  12.  Cunningham M, Azcarate-Peril MA, Barnard A, Benoit V, Grimaldi R, Guyonnet D, Holscher HD, Hunter K, Manurung S, Obis D, Petrova MI, Steinert RE, Swanson KS, van Sinderen D, Vulevic J, Gibson GR. (2021). Shaping the Future of Probiotics and Prebiotics. Trends Microbiol., 29(8):667-685. doi: 10.1016/j.tim.2021.01.003.  
  13. Kristensen NB, Bryrup T, Allin KH, Nielsen T, Hansen TH, Pedersen O. (2016). Alterations in fecal microbiota composition by probiotic supplementation in healthy adults: a systematic review of randomized controlled trials. Genome Med., 8(1):52. doi: 10.1186/s13073-016-0300-5.  
  14.  Fiocchi A, Pawankar R, Cuello-Garcia C, Ahn K, Al-Hammadi S, Agarwal A, Beyer K, Burks W, Canonica GW, Ebisawa M, Gandhi S, Kamenwa R, Lee BW, Li H, Prescott S, Riva JJ, Rosenwasser L, Sampson H, Spigler M, Terracciano L, Vereda-Ortiz A, Waserman S, Yepes-Nuñez JJ, Brożek JL, Schünemann HJ. (2015). World Allergy Organization-McMaster University Guidelines for Allergic Disease Prevention (GLAD-P): Probiotics. World Allergy Organ J., 8(1):4. doi: 10.1186/s40413-015-0055-2.  
  15. Mahdizade Ari M, Teymouri S, Fazlalian T, Asadollahi P, Afifirad R, Sabaghan M, Valizadeh F, Ghanavati R, Darbandi A. (2022). The effect of probiotics on gestational diabetes and its complications in pregnant mother and newborn: A systematic review and meta-analysis during 2010-2020. J Clin Lab Anal., 36(4):e24326. doi: 10.1002/jcla.24326.  
  16. McDougall A, Nguyen R, Nguyen PY, Allen C, Cheang S, Makama M, Mills K, Hastie R, Ammerdorffer A, Gulmezoglu AM, Vogel JP. (2024). The effects of probiotics administration during pregnancy on preeclampsia and associated maternal, fetal, and newborn outcomes: a systematic review and meta-analysis. Am J Obstet Gynecol MFM., 6(4):101322. doi: 10.1016/j.ajogmf.2024.101322.  
  17.  Salminen S, Collado MC, Endo A, Hill C, Lebeer S, Quigley EMM, Sanders ME, Shamir R, Swann JR, Szajewska H, Vinderola G. (2021). The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nat Rev Gastroenterol Hepatol., 18(9):649-667. doi: 10.1038/s41575-021-00440-6. 
  18. Vinderola G, Sanders ME, Cunningham M, Hill C. (2024). Frequently asked questions about the ISAPP postbiotic definition. Front Microbiol., 14:1324565. doi: 10.3389/fmicb.2023.1324565. 

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