With all the different “biotics” on the market, it can be confusing to know which ones you need. But knowing the difference is an important part of making informed decisions about which supplements to take. I will break it down for you, so you can feel informed about how prebiotics, probiotics, and postbiotics work together to support gut and colon health.
While each serves a different purpose, a healthy microbiome depends on all three. Prebiotics are compounds (mostly fiber) that feed your beneficial bacteria (probiotics).⁴ The probiotics then produce beneficial compounds, such as short-chain fatty acids (SCFAs), called postbiotics.¹⁻³
Here's what that pathway looks like: prebiotic (fertilizer) → probiotic (garden) → postbiotic (the fruit).
The relationship among prebiotics, probiotics, and postbiotics helps explain why fiber-rich diets are consistently associated with better microbiome and colon health. This article will teach you everything you need to know about these beneficial compounds and microbes and explore why fiber is the foundation of a healthy gut.
What Are Prebiotics, Probiotics, and Postbiotics?
Before reviewing each “biotic” in detail, here's a brief overview of the main differences between them:
- Prebiotics feed beneficial microbes
- Probiotics are beneficial microbes (typically bacteria and yeasts)
- Postbiotics are the beneficial compounds produced by probiotics
Another way to understand the relationship between these different “biotics” is to think of it as a garden. Think of prebiotics as the fertilizer, probiotics as the garden, and postbiotics as the beneficial fruits produced as a result of fertilizing the garden. Together, they form a thriving ecosystem.
Now, let's explore what makes each different “biotic” unique.
Prebiotics
First, we have prebiotics. These are non-digestible plant components (such as prebiotic fiber and polyphenols). Because the human body cannot digest them, they reach the colon intact. Here, they serve as food for your beneficial gut bacteria. This is why plants are some of the best foods for gut health. Prebiotics are found in foods such as oats, legumes, onions, garlic, underripe bananas, and whole grains.
Probiotics
Probiotics are live, beneficial microorganisms that provide a health benefit when you take them in the correct amounts. They help maintain microbial balance and are found in certain fermented foods, like yogurt, kefir, kimchi, sauerkraut, and miso. However, not all fermented foods contain probiotics. In many cases, the pasteurization process kills the beneficial microbes. That's why it's important to check that the label says "live active cultures."
Postbiotics
Finally, we have postbiotics. These are beneficial compounds produced when your gut bacteria ferment, or feed on, prebiotics. Some of the most well-known postbiotics are short-chain fatty acids (SCFAs). SCFAs, particularly butyrate, are critical for maintaining colon cell health and supporting gut barrier integrity.⁵
Why Is Fiber the Foundation of a Healthy Microbiome?
As a dietitian specializing in digestive wellness, I consistently help people find easy ways to increase fiber for gut health. Fiber is the foundation of a healthy microbiome because it fuels beneficial bacteria, which in turn supports postbiotic production. But despite how important fiber is for both gut health and overall health, it's estimated that 95% of Americans fall short of their daily fiber recommendations.⁶
Research consistently shows that people who eat more fiber have greater microbial diversity in their gut. This increased diversity is associated with a reduced risk of chronic diseases such as type 2 diabetes and certain cancers, and may be due in part to the production of postbiotics, such as butyrate, when your gut bacteria ferment prebiotic fiber in the colon.4,7
If you're trying to add fiber to your meals without completely overhauling your diet, here are some easy meal ideas:
- Add canned beans or chickpeas to chilis, soups, and stews.
- Add red lentils to spaghetti sauce.
- Make overnight oats with shredded apples and chia seeds.
- Snack on Greek yogurt topped with berries, walnuts, and sunflower seeds.
- Switch from white rice or pasta to brown rice, wild rice, quinoa, or whole-wheat pasta.
How Do Postbiotics Support Colon Health?
When it comes to postbiotics and gut health, it comes down to postbiotics creating a gut environment that supports normal digestive function and overall colon health.
Remember the postbiotic SCFAs we discussed earlier? There are three main SCFAs: acetate, propionate, and butyrate. Butyrate is particularly important for supporting gut health because it acts as a fuel source for colon cells. Keeping the colon cells healthy is critical for maintaining a healthy gut barrier.
The gut barrier is like a security gate that allows your body to absorb essential nutrients, water, and vitamins while keeping harmful molecules such as bacteria, toxins, and undigested food particles from entering your bloodstream. If the gut barrier is weakened (commonly known as "leaky gut"), harmful substances can slip through, triggering inflammation that is associated with the development of several chronic diseases, including inflammatory bowel disease (IBD).8
This is why having a diverse microbiome is so important for overall digestive wellness. Since a wide variety of postbiotics are needed to create a healthy gut environment, having diverse microbes that work together to produce these beneficial compounds is critical for gut health.
What Does Emerging Research Say About the Microbiome and Colorectal Cancer?
The rates of colorectal cancer among adults under 50 are increasing, and researchers are investigating how microbiome changes may be contributing to this rise.⁹
Central to this research is the concept of dysbiosis, which describes an imbalance between beneficial and harmful microbes in the gut. While we still don't have a definitive answer as to what a "healthy" microbiome looks like, emerging research suggests that dysbiosis may be a contributing factor to the development of colorectal cancer. 10,11
One potential reason for dysbiosis is inadequate fiber intake. Not eating enough fiber can prevent you from fueling the beneficial microbes in your gut. Just as probiotics form compounds as a result of their metabolic processes, so too can harmful microbes. These harmful microbes produce compounds that can damage the gut, which may be one reason they may be linked to an increased risk of colorectal cancer. 4,11
While researchers continue to investigate the causes of early-onset colorectal cancer and the relationship between the microbiome and colorectal cancer, growing evidence suggests the gut microbiome may be one of several factors influencing long-term colon health. 9-11
Conclusion
Prebiotics, probiotics, and postbiotics work together to create a healthy gut environment, but this process depends on providing the right kinds of fuel for your gut microbiome. Fiber-rich foods help nourish healthy gut bacteria, which in turn produce postbiotics that support digestive and colon health. Taken together, these pathways highlight the importance of diet in overall digestive health.
Support Your Gut Health From the Ground Up
Because fiber serves as the foundation for gut microbiome health, prioritizing daily fiber intake is one of the simplest ways to support beneficial gut bacteria and the postbiotics they produce. If you struggle to meet your fiber goals, try Doctor's Best Prebiotic Fiber, a gentle-on-the-gut prebiotic that supports digestive health, microbiome balance, and daily fiber goals. Or, consider adding a high-quality probiotic or high-absorption postbiotic to support gut health and digestive comfort.
FAQs
What is the difference between prebiotics, probiotics, and postbiotics?
Prebiotics are nutrients (such as fiber and polyphenols) that feed beneficial bacteria and yeasts. Probiotics are the beneficial bacteria and yeasts. Postbiotics are compounds produced when probiotics ferment prebiotic compounds.
Why is fiber considered a prebiotic?
Fiber is considered a prebiotic because certain types of fiber resist digestion. They reach the colon intact, where they serve as food for beneficial gut microbes.
What are postbiotics?
Postbiotics are beneficial compounds produced by gut bacteria during fermentation, including short-chain fatty acids (SCFAs) such as butyrate.
How do prebiotics, probiotics, and postbiotics work together?
Prebiotics nourish probiotics, and probiotics produce postbiotics. Together, they help support a healthy gut ecosystem.
Can gut health affect colon health?
The gut microbiome helps maintain the digestive environment, and researchers continue to study how microbiome health influences long-term colon wellness. In particular, the short-chain fatty acid butyrate serves as a fuel source for colon cells, helping maintain a strong gut barrier.
References
¹ Gibson, G. R., et al. (2017). The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology, 14(8), 491–502.
² Hill, C., et al. (2014). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews Gastroenterology & Hepatology, 11(8), 506–514.
³ Salminen, S., et al. (2021). The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nature Reviews Gastroenterology & Hepatology, 18(9), 649–667.
⁴ Makki, K., et al. (2018). The impact of dietary fiber on gut microbiota in host health and disease. Cell Host & Microbe, 23(6), 705–715.
⁵ Parada Venegas, D., et al. (2019). Short-chain fatty acids (SCFAs)-mediated gut epithelial and immune regulation and its relevance for inflammatory bowel diseases. Frontiers in Immunology, 10, 277.
⁶ U.S. Department of Agriculture & U.S. Department of Health and Human Services. (2020). Dietary Guidelines for Americans, 2020–2025 (9th ed.).
⁷ Valdes, A. M., et al. (2018). Role of the gut microbiota in nutrition and health. BMJ, 361, k2179.
⁸ Bischoff, S. C., et al. (2014). Intestinal permeability—A new target for disease prevention and therapy. BMC Gastroenterology, 14, 189.
⁹ Siegel, R. L., et al. (2024). Colorectal cancer statistics, 2024. CA: A Cancer Journal for Clinicians, 74(3), 203–233.
¹⁰ Wong, S. H., & Yu, J. (2019). Gut microbiota in colorectal cancer: Mechanisms of action and clinical applications. Nature Reviews Gastroenterology & Hepatology, 16(11), 690–704.
¹¹ Janney, A., et al. (2020). Host–microbiota maladaptation in colorectal cancer. Nature, 585(7826), 509–517.
About the Author
Sarah is a registered dietitian specializing in gut health. With over eight years of experience in the health and wellness industry, she combines clinical expertise with lived experience with gut health issues to inform everything she writes. Her goal as a writer is to ensure that complex health information is simplified without losing context so people can make informed decisions about their health. She currently lives in British Columbia, Canada, where she enjoys lifting weights, reading sci-fi/fantasy books, and crocheting in the company of her husband and two cats.