Prebiotics vs Probiotics: What's the Difference?

If you've spent any time reading about gut health and trying on your own to fix it, chances are you've heard of probiotics, prebiotics, or both. And you're not sure whether your problem calls for one of them, both, or neither.

The supplement space isn't short on big claims here, either. You'll often hear that your probiotic won't work without a prebiotic, or that the right probiotic can fix just about any issue you throw at it.

Before you can decide whether you need either one, you have to know what they are. Thankfully, that part's simple. I'll break down what probiotics and prebiotics are, what they're supposed to do, and whether you actually need both. Then I'll show you how you can get most of their benefits without taking a supplement at all.

What's the Difference?

The largest difference between the two is simple: probiotics are alive and prebiotics aren't. Let's take a closer look at each one.

Probiotics

Probiotics are live microorganisms that, when taken in large enough amounts, do something good for your health. This is the definition that researchers use when performing trials on probiotics. There are a few important parts to this definition.

First, it has to be alive. This rules out a lot of products that borrow the word for their marketing.

Second, probiotics must be microbes. Usually they're bacteria, but sometimes yeast. And third, they also have to do something good for you. Being harmless isn't enough. A probiotic earns the title by improving your health.

Most often, probiotics are taken in capsule form which delivers the bacteria straight to your gut. From there, the goal is for those bacteria to colonize and go to work for you.

Prebiotics

Prebiotics are foods that probiotics and other gut bacteria can eat to obtain energy. Again, prebiotics have to lead to a specific health benefit.

In common terms, a prebiotic is most often a fiber that your own body can't digest. These fibers travel all the way through your digestive tract to the colon where bacteria ferment them for energy. A prebiotic doesn't add any bacteria to your gut directly but instead feeds the ones you already have.

How They Work Together

So what are the health benefits that probiotics and prebiotics can provide, and how can they work together?

When fiber in the form of a prebiotic reaches your gut bacteria, it's fermented. This fermentation process produces short-chain fatty acids (SCFAs), mainly butyrate, acetate, and propionate.

These SCFAs can perform several beneficial functions for your gut. They are a fuel source for the cells that line your colon and can help maintain a strong gut barrier that prevents unwanted substances from passing through your gut. When the barrier weakens, things that should stay in your gut can escape, triggering low-grade inflammation. SCFAs also regulate the signals that your gut sends to your immune system and metabolism, and may even be capable of controlling your appetite.

A probiotic simply aims to add more bacteria to your gut that are capable of fermenting fibers and producing SCFAs. Beneficial bacteria also provide benefits by competing for space and eating the food that harmful bacteria would otherwise use. They can also send their own signals that communicate with the immune system.

Here's where it gets messy. Not all probiotics and microbiomes are the same. Many different probiotics contain different strains of bacteria, each with potentially different effects. On top of that, different people's guts are more or less receptive to any given probiotic, so there's no guarantee the one you take is the right fit for you.

The two can be combined into a single product called a synbiotic. This is a probiotic packaged together with the fiber it feeds on.

You don't necessarily have to take prebiotics and probiotics at the same time for either one to work. Consistency over time is more effective than anything else. Your gut won't change overnight, but small changes can add up.

In the end, both aim to help your gut the same way. They just take different routes to get there.

Prebiotic Foods vs. Probiotic Foods

A food is prebiotic when it's rich in fermentable fibers that your gut bacteria can use. Some common prebiotic foods include:

• Asparagus, bananas
• Onions, garlic, leeks
• Legumes
• Chicory root, Jerusalem artichoke

A food is probiotic when it's been fermented and holds live cultures. This just means that microbes have already started breaking the food down and some are still alive by the time it's on your plate. Some common probiotic foods include:

• Kefir
• Yogurt with live cultures
• Sauerkraut
• Kimchi
• Kombucha

Not all fermented foods are technically probiotics, since they can contain live microbe strains that have never been tested for health benefits. For everyday gut support, fermented foods can still be beneficial and a varied mix of them is a low-risk habit either way.

Do You Need Both?

So, which one do you actually need? It depends on your situation.

Prebiotics act similarly to dietary fiber, so technically you can get a prebiotic effect solely from the stuff you eat. The research points to the biggest gut and metabolic benefits seen with an intake around 25 to 30 grams of fiber per day. The catch is that most people don't consume nearly enough fiber to experience its beneficial effects.

Prioritizing more fiber-rich foods in your diet can help you feed your gut bacteria in the same way a prebiotic can. If you struggle to reach your daily fiber intake goals, a prebiotic can help cover your bases at minimal calories.

But my advice is to take an honest look at your diet first before relying on a prebiotic. You might save yourself a trip to the supplement aisle. If those diet changes aren't enough on their own, a prebiotic supplement can help fill the gap.

Probiotics are situation-specific. Since most of the research tests them on how they impact gut-related symptoms, that's what they're best suited for. Their effects are also strain specific. Not all probiotics are equal.

Because of strain-specificity, it can be difficult to find a probiotic that helps your situation. If you do try out a probiotic, treat it like your own mini-trial. Take it consistently for a few weeks and monitor how your symptoms change.

Whether you personally should take one is its own question. To read more on this, check out do you need a probiotic.

When trying out new products or diets, it's best to start small and make one change at a time. That way, you'll know what actually made a positive impact and cut out what doesn't work.

In short, both prebiotics and probiotics have their place, but a capsule isn't the only way to get either one. Start with your diet. It's cheaper and can feed your gut just as well. You might find out you never needed the supplement aisle at all.

Conclusion

Probiotics are live microbes you deliver to your gut. Prebiotics are the foods they live on. Both target the same goal: a gut that performs better and holds up better over time.

They are both commonly marketed products that are available in capsule form for you to take daily. They even come in a combined form known as a synbiotic. However, this isn't the only way to get them. You can get prebiotic foods through your diet by increasing your daily fiber amount. You can also ingest probiotics by eating fermented foods, although their effects may be different from the ones you find in a supplement.