Understanding the Difference Between Probiotics and Postbiotics

Overview

• Probiotics are live microorganisms that deliver a health benefit when taken in the correct amount.
• Postbiotics are non-living microbial preparations (or parts of microbes) that also confer health benefits.
• Probiotics work like active helpers in your gut, interacting with your existing microbial community; postbiotics act more like blueprints—still useful, even if the microbes aren’t alive.
• A postbiotic isn’t just a dead probiotic. It’s a deliberate, studied preparation that’s been scientifically shown to be beneficial in that inanimate state.
• Whether you choose a probiotic or postbiotic, the label should clearly state the microbial strains or preparation and be backed by published research.
• While probiotics are well-established for supporting things like digestive health, postbiotics are an exciting, growing area of study, showing promise for targeted immune support and situations where live microbes aren’t a good fit.

Just when you thought you had probiotics figured out—those helpful microorganisms your gut (and social media feed) can’t stop talking about—another member of the ‘-biotic’ family shows up: postbiotics. Cue confusion. You’re probably wondering, “Are these just expired probiotics with a rebrand?” (Spoiler: not even close.)

Here’s what matters: probiotics are living microbes that interact with your body while they’re active. Postbiotics are carefully prepared non-living microbial cells—or pieces of them—that still deliver scientifically studied effects. In other words, function doesn’t end at the moment of microbial death.

Understanding this distinction helps you make more informed decisions—especially if you’re managing digestive sensitivity, exploring immune support, or trying to decode product labels in the supplement aisle. So if you’re wondering whether your gut would benefit more from the living workforce or the structural blueprints they leave behind, you’re in the right place. 🧠

First Things First: Defining Probiotics and Postbiotics

Before we get into the science of how they work, let’s get clear on definitions. Because when it comes to microbial interventions, precision isn’t optional—it’s essential for interpreting labels and outcomes.

What Are Probiotics? The Live and Kicking Crew

According to the International Scientific Association for Probiotics and Prebiotics (ISAPP), probiotics are “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.”¹

That definition breaks down into three core criteria:

• Live Microorganisms: This is the big one. They must survive digestion and remain viable when they reach your gut.
• Adequate Amounts: You can’t just sprinkle in a few and hope for the best. You’ll often see dosages listed as AFU (Active Fluorescent Units, a newer, more precise measurement method) or CFU (Colony Forming Units, the old-school standard).
• Demonstrated Health Benefit: They must be shown in human studies to do something meaningful for your health.

🔬 And here’s a key distinction: probiotic effects are strain-specific. Just like saying “dog” doesn’t tell you whether it’s a Saint Bernard or a Yorkie (both are Canis lupus familiaris, but one’s built for mountain rescues and the other fits in a tote bag), naming only the genus and species (Lactiplantibacillus plantarum) won’t reveal what it actually does. The full strain ID (like Lactiplantibacillus plantarum LP01) is what links it to scientific outcomes, whether that’s easing occasional bloating or supporting barrier function.

What Are Postbiotics? The Beneficial Bits and Pieces

Now for the newer addition to the microbial toolkit: postbiotics. ISAPP defines these as a “preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”.²

That means:

• Inanimate Microbial Components: Usually heat-treated, these microbes no longer replicate—but still contain functional parts like peptidoglycans, proteins, or other structural elements that can interact with your cells.³
• Confer a Health Benefit: Just like with probiotics, health claims require direct evidence in humans.
• Defined and Standardized: You can’t just throw dead bacteria in a jar and call it a day. A true postbiotic must come from well-characterized organisms using standardized processes.³

Here’s what postbiotics aren’t: expired probiotics. Losing viability doesn’t make a product a postbiotic. If the inanimate form hasn’t been specifically studied and standardized, it doesn’t qualify. The key isn’t just that it’s dead—it’s that it still works. 🧟

How Do Probiotics and Postbiotics Work?

You might be thinking: If one’s alive and one’s not… how can they both help? Let’s walk through their different mechanisms of action.

Probiotics: Your Gut’s Active Support Team

Live probiotics are like a skilled, temporary workforce. They don’t permanently move in (that’s why you need to take them consistently to keep seeing benefits), but while they’re around, they get to work by:

• Mingling with your resident microbes, potentially nudging the gut ecosystem into better balance.
• Producing helpful byproducts, like short-chain fatty acids (SCFAs) such as butyrate (which helps feed the cells lining your colon), acetate, and propionate.⁴
• Reinforcing your gut barrier. Your gut lining is a critical gatekeeper. Certain probiotics, like Bifidobacterium longum CECT 7347, have been studied for their ability to support this barrier, helping keep pathogens and irritants where they belong.⁵
• Engaging immune cells. A large portion of your immune system resides in your gut. Probiotics can interact with cells there, potentially shaping how your body responds to both internal and external signals.⁶

Think of probiotics like houseguests who cook dinner, repair your fence, and leave behind useful tools before heading out the door. 🤝

Postbiotics: Power in the Parts

Postbiotics don’t rely on being alive. Their strength lies in their structure—and how those parts engage your biology:

• Trigger Cellular Signals: Components like cell wall fragments or proteins can bind to receptors on your intestinal or immune cells, launching beneficial signaling cascades.⁷
• Offer Consistency: Because postbiotics are already inactivated and don’t need to survive digestion, their structure and effects stay consistent, dose to dose, batch to batch.
• Modulate Immune Activity: Many postbiotics are studied for their ability to support anti-inflammatory responses through cytokine signaling.³

If probiotics are chefs actively cooking, postbiotics are the recipes, tools, and prepared meals they leave behind. 🍽️

What Benefits Can You Expect? A Scientific Snapshot

Let’s look at what each of these microbial preparations brings to the table—and where the research stands.

Probiotics: Well-Traveled Paths to Wellness

Probiotics have a deep research history and broad usage:

• Smoother Digestion: Often the reason people start looking into probiotics in the first place. Specific strains have been shown to support healthy regularity, ease occasional bloating and gas, and promote digestive comfort. For example, Lactiplantibacillus plantarum LP01 and Bifidobacterium breve BR03 were included in a study that looked at multiple gastrointestinal outcomes, including support for regular bowel movements and reductions in occasional bloating.⁸
• Gut Immune Function Support: Probiotics can interact with gut-associated lymphoid tissue (GALT), a key immune structure that helps the body decide how to respond to incoming signals. When the right strains engage with GALT, they can help support healthy, balanced immune responses.⁹
• Beyond the Gut: A growing body of research points to unexpected partnerships between gut microbial activity and other bodily systems. For example—a well-supported gut has been linked to benefits for skin health and even markers of cardiovascular wellness.¹⁰

Postbiotics: The Precise Newcomers

While newer to the scene, postbiotics are quickly gaining traction in research—and for good reason. 

• Targeted Immune Support: This is one of the most studied areas of postbiotic function. Certain preparations of inanimate microbes have been shown to influence the immune system’s signaling pathways—especially in calming overactive inflammatory responses.⁷
• Symptom Relief in Specific Situations: Some postbiotics have shown promise for gut symptoms like occasional diarrhea or discomfort associated with Irritable Bowel Syndrome (IBS). A heat-inactivated version of Bifidobacterium bifidum MIMBb75, for example, has been studied for its effects on IBS symptoms.¹¹
• An Option for Sensitive Systems: In some cases—like among people who are immunocompromised—introducing live microbes could carry risks. Postbiotics may offer a safer option, allowing for microbial-derived benefits without the need for viability.¹²
• Shelf-Stable Convenience: Freeze-dried postbiotic preparations are generally much more stable than probiotics. This means they can be easier to formulate into different products and can maintain their potency without worrying about cell viability, a big practical plus. They’re less fragile—yet still functional.²

Imagine needing microbial support but not wanting to take chances with live organisms—postbiotics step in like a shelf-stable safety net that still delivers results. 

Making an Informed Choice: Probiotic or Postbiotic?

If you’re trying to decide between a probiotic and a postbiotic, the best place to start is with your own goals. What’s happening in your body? What kind of support are you looking for? And what does the science say about the strains or preparations offered?

Probiotics Are a Fit When:

Given their extensive research and dynamic activity, probiotics are a well-established choice for:

• Ongoing Digestive Support: Especially for easing occasional bloating, gas, or irregularity, probiotics offer live, active engagement with your gut microbiome.
• Broad Microbiome Reinforcement: Probiotics can help support the balance of your existing microbial community, particularly if your ecosystem has been disrupted.
• Gut Health During and After Antibiotics: Live strains can support recovery of microbial diversity and barrier function if antibiotics throw your gut microbiome out of whack.
• Targeted Benefits: When the strain is listed—and the dosage matches what’s been studied—you can feel more confident that you’re choosing something shown to work in real people.

If you’re choosing a probiotic, look for one that clearly lists the full strain names, provides a clinically relevant dose, and uses a delivery system that helps the microbes survive digestion (like Seed’s ViaCap®). This ensures that those live organisms reach your gut ready to engage. 💪

Postbiotics Might Be Right If:

Postbiotics are an area to watch, and could be particularly interesting if:

• Live Microbes Concern You: Postbiotics are ideal in cases where live microbial activity might pose a risk or simply isn’t desired.
• You Want Highly Specific Immune Effects: As the science develops, we might find that particular postbiotic preparations have highly precise effects on, say, immune signaling.
• Ultra-Stable Formulations Are Required: If you need something travel-ready or want less concern over viability, postbiotics can offer consistent dosing without the fragility of live organisms.

“While live probiotics are foundational to many strategies for gut health, the science of postbiotics opens new doors,” explains Dirk Gevers, Ph.D., Seed Health’s Chief Scientific Officer. “Understanding how inanimate microbial preparations or their specific components can confer benefits is a fascinating frontier. At Seed, we’re committed to exploring the full potential of the microbiome.”

The Key Insight

At the core, probiotics and postbiotics differ by one thing: viability. But the bigger takeaway isn’t just “live vs. not-live”—it’s what each is designed to do, and what it’s been shown to deliver.

A probiotic is a live microorganism that’s studied to perform a specific function while actively interacting with your gut. A postbiotic is an intentionally inactivated preparation of microbes (or their parts) that still delivers benefits.

Both require the same standard: scientific proof, clear definition, and consistent preparation. If a product doesn’t meet those criteria, it doesn’t deserve the label.

So don’t choose based on buzzwords—choose what’s seeded in science. 🌱

Frequently Asked Questions (FAQs)

Are Postbiotics “Better” Than Probiotics?

Not better—just different. Probiotics work through live microbial activity; postbiotics work through physical components. Which is right for you depends on your health needs, sensitivities, and the product’s scientific backing.

Can You Take Probiotics and Postbiotics at the Same Time?

Yes, in most cases. Since they work through different mechanisms, they’re often complementary. But it’s still smart to introduce one at a time—especially if your gut tends to be reactive—so you can observe how your body responds. Always talk to your healthcare provider if you have questions or medical conditions.

What Are Some Examples of Postbiotic Ingredients?

Examples include heat-inactivated Bifidobacterium bifidum MIMBb75 or exopolysaccharides from Lacticaseibacillus paracasei IJH-SONE68.^11,13 These preparations are standardized and studied in their non-living form.

Do Postbiotics Have Side Effects?

Postbiotics are generally considered to have a good safety profile.¹² They’re less likely to cause mild adjustment symptoms (like a bit of extra gas or bloating) that some people experience with live probiotics. Still, everybody is different—so choose well-studied products and consult your provider if you’re unsure.