In recent years, the terms "prebiotics" and "probiotics" have become common buzzwords in the health and wellness world, particularly when discussing gut health.
While both play vital roles in maintaining a healthy digestive system, they serve different functions. Understanding the difference between prebiotics and probiotics and how they complement each other can help you make informed decisions about your health.
What Are Prebiotics?
Prebiotics are non-digestible food components or substrates that are selectively used by the body to stimulate the growth and activity of beneficial microorganisms and confer a health benefit. In simple terms, they act as food for the good bacteria already living in your digestive system.
The most common prebiotics are types of fiber, specifically oligosaccharides and inulin, that resist digestion in the small intestine and pass into the large intestine, where they serve as fuel for the microbiota.
Sources of Prebiotics:
- Fiber-rich foods: Whole grains, bananas, onions, garlic, leeks, asparagus, and artichokes.
- Resistant starch: Found in foods like under-ripe bananas, potatoes, and legumes.
- Inulin: A type of soluble fiber found in chicory root, onions, and garlic.
These fibers pass through the small intestine undigested and enter the colon, where they are fermented by gut bacteria. The byproducts of this fermentation are short-chain fatty acids (SCFAs) such as butyrate, propionate, and acetate, which have numerous health benefits, including:
- Gut Health: SCFAs help maintain the integrity of the gut lining and support the immune system.
- Reduced Inflammation: They have anti-inflammatory effects, contributing to lower levels of chronic inflammation.
- Enhanced Digestion: Prebiotics can aid digestion and reduce symptoms like constipation or bloating.
What Are Probiotics?
Probiotics are live microorganisms, typically bacteria or yeast, that provide health benefits when consumed in adequate amounts that confer a health benefit. These “good” microorganisms contribute to maintaining or restoring a healthy balance of gut flora by outcompeting harmful bacteria.
Sources of Probiotics:
- Fermented foods: Yogurt, kefir, sauerkraut, kimchi, miso, and kombucha.
- Probiotic supplements: Available in capsules, powders, or liquids, with specific strains like Lactobacillus, Bifidobacterium, and Saccharomyces boulardii being among the most studied.
They can also be consumed in supplement form, often as capsules or powders containing various strains of bacteria like Lactobacillus and Bifidobacterium. Some key benefits of probiotics include:
- Restoring Gut Flora Balance: After disruptions from illness, antibiotics, or poor diet, probiotics help restore a healthy balance of gut bacteria.
- Digestive Health: Probiotics can reduce symptoms of irritable bowel syndrome (IBS), diarrhea (especially after antibiotic use), and constipation.
- Immune Support: Probiotics support the gut-associated lymphoid tissue (GALT), which is an essential part of your immune system.
- Mental Health: Could improve mental health by influencing the gut-brain axis, and support the production of neurotransmitters, potentially alleviating anxiety and depression.
How Prebiotics and Probiotics Work Together (Synbiotics)
Although prebiotics and probiotics have different roles, they can often be more effective in certain instances when used together. This concept is known as synbiotics: a mixture of live microorganisms and substrates selectively used by a host that confers a health benefit.
What Are Postbiotics?
Postbiotics are formulations of inanimate microorganisms and/or their components that offer health benefits to the host. Unlike probiotics, which contain live microorganisms, postbiotics are made up of non-living microorganisms or their components, either with or without metabolites like short-chain fatty acids (SCFAs), and retain their health benefits even after the probiotic bacteria have been inactivated.
Sources of Postbiotics: Postbiotics are typically a result of the processing of probiotics.
Benefits of Postbiotics:
- May help reduce inflammation in the gut and other parts of the body.
- May support gut health by preserving the integrity of the gut lining.
- May offer immune-modulating effects, improving the body’s response to infections.
Conclusion
The human gut is home to trillions of microorganisms that play a critical role in everything from digestion to immune function to even mental health. Understanding the roles of prebiotics, probiotics, postbiotics, and synbiotics can help us make informed decisions about how to support our gut health.
A balanced gut microbiome is essential for overall health, and incorporating prebiotics, probiotics, postbiotics, and synbiotics into your diet can be an effective strategy for improving your gut health. While probiotics and prebiotics have been the focus of many health conversations, postbiotics and synbiotics represent an exciting frontier in gut health research, offering new ways to support the gut microbiota and its many functions.
When considering these options, remember that no single approach will work for everyone. What works best for you may depend on your unique microbiome, health conditions, and lifestyle.
Interested in learning more? Read our most popular blog on Resistant Starch
References
Quigley EMM. Prebiotics and Probiotics in Digestive Health. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association. 2019;17(2). doi:10.1016/j.cgh.2018.09.028
Zandifar A, Badrfam R, Mohammaditabar M, et al. The Effect of Prebiotics and Probiotics on Levels of Depression, Anxiety, and Cognitive Function: A Meta‐Analysis of Randomized Clinical Trials. Brain and Behavior. 2025;15(3):e70401.
Swanson KS, Gibson GR, Hutkins R, et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics. Nature Reviews Gastroenterology & Hepatology. 2020;17(11):687-701.
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. Nature Reviews Gastroenterology & Hepatology. 2021;18(9):649.
