Prebiotics vs. probiotics: What they do and why you need both

Maybe you've been stocking up on yogurt because you heard it's good for your gut. Or grabbed a prebiotic soda at the store and wondered if it's actually doing anything. Prebiotics and probiotics both get a lot of attention, but there are key differences between the two.

Let's break down what each one does, where to find them and why your gut needs both.

What are probiotics?

Probiotics are live bacteria and yeasts that help break down food, support your immune system and keep inflammation in check. There's a good chance you're already getting some without thinking about it. Fermented foods like yogurt, kimchi and kefir are all natural sources of probiotics.

Not all probiotics work the same way, though—different strains do different things, which is why eating a variety of fermented foods tends to be more useful than sticking with just one.

What are prebiotics?

Prebiotics are types of fiber your body can't digest. Instead of breaking them down for energy, your gut passes them along to the beneficial bacteria already living there—and those bacteria use them as fuel.

They can be found in fiber-rich foods like:

• Whole grains
• Lentils
• Fruits

Prebiotics vs. probiotics: What’s the difference?

Probiotics add new beneficial bacteria to your gut, while prebiotics feed the bacteria that are already there. Both play a role in keeping your digestive system balanced, and you get the most benefit when you're getting enough of each.

How prebiotics and probiotics work together

When your gut has a healthy balance of bacteria and enough fuel to keep them working, the benefits go beyond digestion. Prebiotics and probiotics work together to:

• Improve how well your body absorbs nutrients
• Improve digestion
• Reduce inflammation
• Reduce gas and bloating
• Strengthen your immune system
• Support regular bowel movements

Where are prebiotics and probiotics found?

Prebiotics and probiotics can be:

• Added to foods
• Found in fiber-rich foods and foods with live, active cultures
• Taken as supplements

For most people, the easiest place to start is with the foods you're already eating. A well-balanced diet can provide all the nutrients that your body needs to function well.

Foods high in prebiotics and probiotics

Adding prebiotics and probiotics to your diet doesn't have to be complicated. Small choices throughout the day can go a long way toward supporting a healthy gut.

Here are some of the most common sources of each, along with a few easy ways to pair them.

Foods high in prebiotics

• Apples
• Asparagus
• Bananas
• Cold, boiled potatoes
• Flaxseeds
• Garlic
• Jerusalem artichoke
• Leeks
• Lentils and beans
• Mushrooms
• Nuts such as almonds and cashews
• Oats
• Onions

Foods high in probiotics

• Buttermilk
• Fermented vegetables, like pickles, beets or carrots
• Fermented soy or coconut milk
• Kefir
• Kimchi
• Kombucha
• Miso
• Pickled vegetables
• Raw, unpasteurized cheeses like cheddar, mozzarella and gouda
• Sauerkraut
• Tempeh
• Yogurt that contains added Lactobacillus and Bifidobacterium strains

Eating prebiotics and probiotics together, sometimes called a “synbiotic” combination, helps the good bacteria make it to your gut, where they’re needed the most.

Should you take a prebiotic or probiotic supplement?

Sometimes your gut bacteria can get thrown off balance—after a course of antibiotics, during a period of high stress, while traveling or if you have a condition like irritable bowel syndrome (IBS). When that happens, supplements may help restore what's been disrupted.

But the strain, how the product is stored and the quality of the formula all affect whether the bacteria survive long enough to do any good.

Not all supplements contain the same types of bacteria or the same concentrations, and many products make claims without strong evidence to back them up. Probiotic supplements are also not regulated by the FDA the same way medications are, which makes it harder to know exactly what you're taking.

If you're considering a prebiotic or probiotic supplement, talk to your healthcare provider about which strains and products are the best fit for you. For many people, gut health can be supported through a balanced diet. Supplements work best as a complement to a well-balanced diet—not as a substitute for one.

The bottom line on prebiotics vs. probiotics

Think of prebiotics and probiotics as a team. They support gut health in different ways, and having enough of both helps your digestive system do its job.

For many people, a balanced diet that includes a mix of fiber‑rich and fermented foods is a practical place to start. Supplements can be helpful in certain situations, but they tend to work best alongside food, not as a replacement for it.

If you’re dealing with ongoing digestive symptoms or are wondering whether supplements may be right for you, your healthcare provider can help you decide what’s right for your body and your needs.

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