What Are Postbiotics? The Gut Health’s New Frontier

Postbiotics are the beneficial compounds produced by probiotics when they consume prebiotics in your gut. 

While the worlds of prebiotics and probiotics have long dominated conversations about gut health, this emerging third “-biotic” is now recognized as a key player in delivering the health benefits we’ve often attributed solely to its predecessors.

In fact, many of the positive effects of probiotics are actually delivered by the postbiotics they create.

With over 60 million Americans affected by digestive diseases, understanding every tool available for gut health is crucial.

Postbiotics represent a paradigm shift, moving from a focus on live organisms to the bioactive substances they produce.

This comprehensive guide will explore the science behind postbiotics, their proven benefits, how they compare to other “-biotics”, and how you can leverage them to support your overall well-being.

What Exactly Are Postbiotics? A Scientific Definition

For years, the focus has been on ingesting live “friendly” bacteria (probiotics) and feeding them with specific fibers (prebiotics).

However, research has revealed that the story doesn’t end there. The real magic often happens with what’s left behind after this interaction.

Beyond the “Waste Product” Misconception

Postbiotics are often simplified as the “waste products” of probiotics, but this term is misleading.

A more accurate description is that they are bioactive compounds generated during a fermentation process.

These are not inert byproducts, they are functional molecules that can directly influence your body’s physiological processes, especially within the gut and immune system.

A 2019 review in the International Journal of Molecular Sciences emphasizes that many of the health benefits linked to prebiotics and probiotics actually come from the production of postbiotics.

This insight has led to a reappreciation of these compounds as powerful health-promoting agents in their own right.

The Official Definition: A Look at the Science

While a single, universally accepted definition is still being finalized by scientific bodies, a comprehensive working definition has been proposed:

“Postbiotics are functional bioactive compounds, generated in a matrix during fermentation, which may be used to promote health. Postbiotics can include many different constituents including metabolites, short-chain fatty acids (SCFAs), microbial cell fractions, functional proteins, extracellular polysaccharides (EPS), cell lysates, teichoic acid, peptidoglycan-derived muropeptides and pili-type structures.”
– Wegh et al., Int J Mol Sci. 2019

This definition highlights two key aspects: postbiotics are produced by microorganisms and they contain a complex mixture of beneficial components, not just one single substance.

This includes both the substances secreted by bacteria and fragments of the dead bacteria themselves.

Prebiotics + Probiotics = Postbiotics: The Gut’s Fermentation Factory

The relationship between the “-biotics” can be understood as a simple biological process:

1. You consume Prebiotics (e.g., fiber from garlic, onions, or bananas). These are non-digestible foods that travel to your colon.
2. Probiotics (the beneficial bacteria living in your gut, like Bifidobacterium and Lactobacillus) use these prebiotics as food.
3. Through the process of fermentation, the probiotics break down the prebiotics and produce Postbiotics (e.g., butyrate, vitamins, and other beneficial compounds).

Therefore, a healthy gut environment rich in both prebiotics and probiotics is a natural postbiotic factory.

How Do Postbiotics Differ from Probiotics and Prebiotics?

Understanding the distinction between these three terms is key to appreciating the unique role of postbiotics.

While they work together synergistically, they are fundamentally different in their composition and function.

Here is a detailed comparison:

Feature	Prebiotics	Probiotics	Postbiotics
Definition	A substrate that is selectively utilized by host microorganisms conferring a health benefit. Essentially, “food” for good bacteria.	Live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.	Bioactive compounds produced by microorganisms during fermentation, including metabolites and cell components.
State	Non-living food components (e.g., fiber).	Living microorganisms.	Non-living compounds and bacterial fragments.
Primary Function	To nourish and stimulate the growth of beneficial gut bacteria.	To introduce beneficial bacteria into the gut ecosystem.	To provide direct health benefits to the host and modulate biological responses.
Examples	Fructans (inulin, FOS), galactooligosaccharides (GOS), found in foods like chicory root, garlic, leeks, and asparagus.	Lactobacillus and Bifidobacterium species found in yogurt, kefir, sauerkraut, and kimchi.	Short-chain fatty acids (butyrate, acetate), vitamins (B and K), amino acids, enzymes, and cell wall fragments.
Key Advantage	Easy to incorporate into diet through high-fiber foods.	Can help restore gut flora after disruption (e.g., antibiotics).	More stable, longer shelf-life, and safer for immunocompromised individuals as they are not live organisms.
Source for Body	Dietary intake of specific plant fibers.	Dietary intake of fermented foods or supplements.	Produced internally by gut bacteria or consumed directly via supplements or fermented foods.

What Are the Different Types of Postbiotic Compounds?

The term “postbiotic” is an umbrella for a diverse array of molecules, each with unique functions.

The composition of a postbiotic mixture depends on the probiotic strain and the prebiotic substrate used in fermentation.

Here are the major categories:

• Short-Chain Fatty Acids (SCFAs): These are the most well-studied postbiotics. The main three are butyrate, propionate, and acetate. Butyrate is the primary energy source for colon cells and has potent anti-inflammatory properties.
• Cell Wall Fragments: Pieces of the bacterial cell wall, such as peptidoglycans and teichoic acids, can directly interact with immune cells in the gut lining, helping to regulate immune responses.
• Functional Proteins: Certain enzymes and peptides secreted by probiotics can have antimicrobial effects, helping to inhibit the growth of harmful pathogens.
• Extracellular Polysaccharides (EPS): These are complex carbohydrates secreted by bacteria. They can have antioxidant and cholesterol-lowering effects and also act as prebiotics for other beneficial bacteria.
• Cell-Free Supernatants: This refers to the liquid mixture of compounds produced by bacteria and yeast during fermentation after the cells themselves have been removed. It contains a rich cocktail of all the secreted postbiotic molecules.
• Bacterial Lysates: A mixture made from broken-down bacterial components, ensuring all the beneficial intracellular and cell wall components are present.
• Other Metabolites: This broad category includes essential nutrients like vitamins B and K and various amino acids, which are synthesized by gut bacteria and are vital for human health.

How Do Postbiotics Work? The Scientific Mechanisms

Unlike probiotics, which must survive the harsh journey through the stomach to colonize the gut, postbiotics can exert their effects more directly.

Their non-living nature allows them to interact with the host system in several key ways without the need for colonization.

Immunomodulation: Calming and Training the Immune System

One of the most significant functions of postbiotics is their ability to modulate the immune system.

The gut is home to about 70% of the body’s immune cells, and postbiotics act as key signaling molecules.

• Anti-Inflammatory Action: SCFAs like butyrate can inhibit inflammatory pathways. Research shows butyrate can stimulate the production of regulatory T cells (Tregs), which are crucial for preventing excessive immune reactions and maintaining tolerance .
• Immune Signaling: Cell wall fragments and other microbial components can interact with specific receptors on intestinal cells, such as Toll-like receptors (TLRs). This interaction can trigger a cascade of signals that either dampen inflammation or prime the immune system to fight off pathogens more effectively. For example, studies on fermented infant formula containing postbiotics showed they could induce high IL-10 production (an anti-inflammatory cytokine) through a TLR-2 pathway .

Strengthening the Gut Barrier

A healthy gut barrier is essential for preventing harmful substances from leaking into the bloodstream (a condition often called “leaky gut“).

Postbiotics play a vital role in maintaining this barrier.

• Fueling Colon Cells: Butyrate is the preferred energy source for the cells lining the colon (colonocytes). A well-nourished colon lining is stronger and less permeable.
• Enhancing Tight Junctions: Postbiotics can help reinforce the “tight junctions”, which are protein structures that seal the space between intestinal cells. Akkermansia muciniphila-derived extracellular vesicles (a type of postbiotic) have been shown to improve gut permeability by regulating these junctions .

Antimicrobial and Pathogen Inhibition

Postbiotics help maintain a healthy balance of microbes by creating an environment that is inhospitable to pathogens.

• Lowering Gut pH: The production of SCFAs and other organic acids lowers the pH of the colon. This acidic environment inhibits the growth of many harmful, pH-sensitive bacteria like E. coli and Clostridium difficile.
• Producing Antimicrobial Peptides: Some postbiotics are bacteriocins, which are natural antimicrobial peptides that can directly kill or inhibit competing pathogenic bacteria.

What Are the Science-Backed Benefits of Postbiotics?

While research is still evolving, a growing body of evidence supports a wide range of health benefits associated with postbiotics.

Many of these benefits were previously attributed to probiotics, but we now understand that postbiotics are often the direct mediators of these effects.

May Help Boost the Immune System and Fight Infections

Postbiotics have demonstrated a clear ability to strengthen the immune system.

Studies show they can reduce the risk and severity of common infections.

• A 12-week study in 80 healthy older adults found that daily postbiotic supplementation significantly lowered their risk of respiratory infections and improved their ability to produce protective antibodies .
• Another study involving 300 elderly adults showed that those taking a high-dose postbiotic supplement had a significantly lower incidence of the common cold compared to the placebo group .

May Help Reduce Digestive Symptoms and IBD

Given their direct action in the gut, it’s no surprise that postbiotics are beneficial for digestive health, particularly for inflammatory conditions.

• Inflammatory Bowel Disease (IBD): People with IBD (Crohn’s disease and ulcerative colitis) often have lower levels of SCFAs like butyrate. Supplementing with butyrate has shown promise. A small study on patients with mild-to-moderate Crohn’s disease found that taking 4 grams of butyrate daily for 8 weeks led to clinical remission in 53% of participants .
• Irritable Bowel Syndrome (IBS): A 4-week study in 297 adults with IBS found that a postbiotic supplement significantly reduced bowel movement frequency, bloating, and pain, leading to an improved quality of life.

May Help Prevent and Treat Diarrhea

Postbiotics have shown efficacy in managing various types of diarrhea, sometimes even outperforming probiotics.

• Childhood Diarrhea: A review of seven studies involving 1.740 children concluded that postbiotic supplementation significantly reduced the duration of diarrhea.
• Antibiotic-Associated Diarrhea: Another review of 23 studies found postbiotics were significantly more effective than a placebo at preventing diarrhea caused by antibiotic use in children.
• Chronic Diarrhea in Adults: A 2003 study compared a postbiotic supplement to a probiotic supplement in 137 adults with chronic diarrhea. After 4 weeks, the postbiotic was found to be more effective at treating the condition.

Other Potential Benefits

Research is uncovering a host of other potential benefits, though more human studies are needed to confirm these effects:

• Allergies: A study on adults with atopic dermatitis (eczema) found that an 8-12 week course of postbiotic supplementation significantly reduced the severity of the condition.
• Weight Management: Some studies suggest that SCFAs may help suppress hunger signals, potentially aiding in weight loss efforts.
• Heart Health: Animal studies indicate that butyrate may help lower blood pressure and suppress genes involved in cholesterol production.
• Blood Sugar Control: Butyrate has also been shown in some studies to help manage blood sugar levels.
• Anti-Tumor Properties: In test-tube and animal studies, certain postbiotics have shown the ability to suppress the growth of some cancer cells, including colon and stomach cancer.

Are Postbiotics Safe? Potential Side Effects and Considerations

One of the most significant advantages of postbiotics is their strong safety profile.

Because they do not contain live microorganisms, they eliminate the risks associated with introducing live bacteria into the system, making them a potentially safer alternative for certain populations.

General Safety and Tolerability

For the general healthy population, postbiotics are considered very safe and well-tolerated.

Direct supplementation with postbiotics typically does not cause the digestive side effects sometimes associated with probiotics, such as gas or bloating, which can occur as the gut microbiome adjusts to new live bacteria.

However, if you are increasing your postbiotic production naturally by consuming more prebiotic fibers, you might experience temporary gas, bloating, or mild stomach discomfort as your gut bacteria adapt to the increased fiber intake.

These symptoms usually subside within a few days.

A Safer Alternative for Vulnerable Groups

The absence of live organisms makes postbiotics a particularly attractive option for individuals with compromised or immature immune systems, for whom probiotics may pose a risk of infection.

“It has been suggested that using postbiotics could be an attractive alternative for other ‘-biotics’ in critically ill patients, young children and premature neonates.”
– Wegh et al., Int J Mol Sci. 2019

This includes:

• Individuals with compromised immune systems.
• Critically ill patients.
• People who have recently undergone surgery.
• Premature infants.

While postbiotics themselves are safe, it’s important to distinguish them from the probiotic foods used to produce them.

Certain groups, such as pregnant people and those with specific digestive or heart disorders, should exercise caution with high-dose probiotic foods and supplements and consult a healthcare professional .

How Can You Increase Postbiotics in Your System?

You have two primary methods for increasing the levels of beneficial postbiotics in your body: producing them naturally through your diet or taking them directly as a supplement.

Method 1: Create Your Own Postbiotic Factory (Dietary Approach)

The most natural and holistic way to boost your postbiotic levels is to provide your gut with the raw materials it needs.

This involves consuming a diet rich in both prebiotics and probiotics.

Step 1: Eat More Prebiotic-Rich Foods

Prebiotics are the fibers that feed your beneficial gut bacteria. Focus on incorporating a variety of these foods into your diet:

• Garlic, Onions, and Leeks: Rich in fructans.
• Asparagus: A great source of inulin.
• Chicory Root: Often used in fiber supplements and some coffee alternatives.
• Barley and Oats: Contain beta-glucans.
• Flaxseed: A good source of fiber and healthy fats.
• Under-ripe Bananas: Contain resistant starch, which functions as a prebiotic.
• Seaweed: A potent source of unique polysaccharides.

Step 2: Consume Probiotic-Rich Fermented Foods

These foods contain the live bacteria that will ferment the prebiotics you eat. Look for products with “live and active cultures”.

• Yogurt: Choose plain, unsweetened yogurt with live cultures.
• Kefir: A fermented milk drink with a more diverse range of bacteria and yeasts than yogurt.
• Sauerkraut: Fermented cabbage. Choose refrigerated, unpasteurized versions.
• Kimchi: A spicy Korean fermented vegetable dish.
• Miso and Tempeh: Fermented soy products.
• Kombucha: A fermented tea beverage. Be mindful of sugar content.

Method 2: Direct Supplementation

For a more targeted approach, you can take postbiotic supplements directly.

This bypasses the need for fermentation in your gut and delivers the beneficial compounds straight to your system.

This can be particularly useful for individuals whose gut microbiome may not be efficient at producing postbiotics.

Postbiotic supplements are becoming more widely available in health food stores and online.

They may be labeled as “postbiotic” or by the name of their primary compound, such as sodium butyrate or calcium butyrate.

What Should You Look for in a Postbiotic Supplement?

As the market for postbiotics grows, so does the number of products available.

Navigating the options can be confusing. Here are key factors to consider when choosing a postbiotic supplement.

1. Identify the Core Compound

Unlike probiotics, which are listed by strain (e.g., Lactobacillus rhamnosus GG), postbiotic supplements are often defined by their chemical components.

Look for specific compounds on the label:

• Butyrate: This is the most common and well-researched postbiotic supplement. It may be listed as sodium butyrate, calcium butyrate, or tributyrin (a more stable form).
• Heat-Treated or Inactivated Probiotics: Some products are labeled with the probiotic strain but specify that it is “heat-killed”, “inactivated”, or “tyndallized”. These are technically postbiotics (also called paraprobiotics) because they contain the beneficial cell fragments without live organisms. Examples include heat-killed Lactobacillus paracasei or L. plantarum.
• Fermentates: Look for terms like “dried yeast fermentate” or “fermented culture medium”. These products contain the complex mixture of metabolites produced during fermentation.

2. Check for Third-Party Testing

The supplement industry is not tightly regulated by the FDA. To ensure quality, purity, and potency, look for products that have been voluntarily tested by a third-party organization.

Seals from organizations like NSF International, U.S. Pharmacopeia (USP), or ConsumerLab.com indicate that the product contains what the label says it does and is free from contaminants.

3. Consider the Delivery System

Some postbiotics, particularly butyrate, have a strong, unpleasant odor. Furthermore, they need to reach the colon to be most effective.

To address this, many manufacturers use special delivery systems:

• Enteric Coating or Delayed-Release Capsules: These coatings are designed to resist stomach acid and release the contents further down in the digestive tract, ensuring the postbiotics reach the large intestine where they are most needed.
• Tributyrin Form: This is a precursor to butyrate that is more stable and has less odor. The body converts it into butyrate in the gut.

4. Start with a Low Dose

If you are new to postbiotic supplements, especially butyrate, it’s wise to start with a lower dose and gradually increase it.

This allows your body to adjust. Follow the manufacturer’s instructions or the advice of your healthcare provider.

A typical starting dose for butyrate might be around 300-600 mg per day, but this can vary widely depending on the product and your individual needs.

The Future of Postbiotics: Regulation and Personalized Nutrition

The field of postbiotics is rapidly advancing, moving from a niche scientific concept to a mainstream component of health and wellness.

This evolution brings both exciting opportunities and important challenges, particularly in the areas of regulation and personalization.

The Regulatory Landscape

Currently, postbiotics fall into a gray area of regulation. In the United States, the FDA does not have a specific category for postbiotics.

They are generally regulated as “dietary supplements”, which means they do not require pre-market approval for safety and efficacy in the same way that drugs do.

The responsibility falls on manufacturers to ensure their products are safe and that their claims are truthful and not misleading.

As the science solidifies, we can expect more specific regulatory guidance. A clear, consensus-based definition is the first step, which will allow for better quality control, standardized testing, and more accurate health claims.

This will ultimately help consumers make more informed and safer choices.

The Promise of Personalized Nutrition

Perhaps the most exciting frontier for postbiotics is their potential role in personalized nutrition.

Since the effects of prebiotics and probiotics can vary significantly between individuals based on their unique gut microbiome, postbiotics offer a more direct and predictable approach.

Imagine a future where:

• Microbiome testing can identify deficiencies in specific postbiotic compounds (like butyrate).
• Based on this data, a healthcare provider can recommend a targeted postbiotic supplement to restore balance.
• This approach could be used to manage specific conditions, from IBD to metabolic disorders, with a level of precision not possible with a one-size-fits-all probiotic.

Postbiotics may allow us to bypass the variability of an individual’s gut “fermentation factory” and deliver the exact beneficial molecules needed to support health, paving the way for a new era of precision gut health management.

Frequently Asked Questions (FAQ)

1. Can I get postbiotics from food?

Yes, indirectly. By eating prebiotic-rich foods (like garlic and oats) and probiotic-rich foods (like yogurt and kefir), you encourage your gut bacteria to produce postbiotics naturally. Some fermented foods may also contain postbiotics that were created during the fermentation process.

2. Are postbiotics better than probiotics?

Not necessarily “better”, but different. Postbiotics offer advantages in stability and safety, especially for immunocompromised individuals. Probiotics are beneficial for introducing live, active bacteria to the gut. The best approach often involves a combination of pre-, pro-, and postbiotics.

3. What is the main benefit of taking postbiotics?

The main benefits are direct support for gut health and immune function. Postbiotics like butyrate provide energy for colon cells, reduce inflammation, and strengthen the gut barrier, all without requiring live organisms to colonize the gut.

4. Do postbiotics have side effects?

Postbiotic supplements are generally very well-tolerated with minimal side effects. If you increase fiber (prebiotics) to make postbiotics, you might experience temporary gas or bloating. When starting a butyrate supplement, some people report initial mild digestive changes.

5. How long does it take for postbiotics to work?

This varies by individual and the benefit being sought. Some people may notice improvements in digestive symptoms within a few days to a week, while systemic benefits like improved immune function may take several weeks of consistent use to become apparent.

6. Can children take postbiotics?

Postbiotics are considered a potentially safer alternative to probiotics for children, especially those who are ill or have compromised immune systems. Fermented infant formulas (a type of postbiotic) have been studied for safety in infants. Always consult a pediatrician before giving any supplement to a child.

7. What is butyrate?

Butyrate is the most well-known postbiotic. It is a short-chain fatty acid (SCFA) that serves as the primary fuel source for the cells lining your colon. It has powerful anti-inflammatory properties and is crucial for maintaining a healthy gut barrier.

8. Do I need postbiotics if I already take prebiotics and probiotics?

If you have a healthy gut, a good diet of pre- and probiotics may be sufficient. However, a postbiotic supplement can be beneficial if your body isn’t efficient at producing them, or if you want a more direct, targeted dose of beneficial compounds.

The Bottom Line

Postbiotics represent the next wave in our understanding of gut health, shifting the focus from the live bacteria themselves to the powerful, health-promoting compounds they produce.

These non-living metabolites and cell fragments offer a range of science-backed benefits, including strengthening the immune system, reducing inflammation, improving digestive symptoms, and reinforcing the gut barrier.

With their superior stability and safety profile, postbiotics provide a reliable and direct way to support your body’s functions, especially for those who may not tolerate probiotics well or have compromised immune systems.

You can boost your levels naturally by consuming a diet rich in prebiotic fibers and probiotic-rich fermented foods, or you can opt for targeted supplementation with products like butyrate.

As research continues to grow, postbiotics are poised to become a cornerstone of personalized nutrition and gut health management.

If you’re looking to take your health to the next level, exploring the world of postbiotics is a promising step forward.

Have you tried postbiotics or focused on a diet to increase them? Share your experience in the comments below!

Disclaimer: The content in this article is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Reference

[1] https://www.healthline.com/nutrition/postbiotics

[2] https://pmc.ncbi.nlm.nih.gov/articles/PMC6801921

[3] https://www.health.harvard.edu/nutrition/what-are-postbiotics