Your Gut Needs Prebiotics and Probiotics—but What's the Difference? This RD Breaks It Down

Laura Fisher

A gut health expert gives the rundown on how both prebiotics and probiotics relate to your microbiome.

Sometimes, the world of wellness confounds me. I meditate, take my CBD, and drink my green juice. But every time I think I’ve got my bases covered, I find out about something else I should be incorporating into my diet. Some of these are just health trends (no thanks, detox tea), but some are actually backed up by science and worth paying attention to. Given the importance of gut health, when I started repeatedly coming across mentions of prebiotics, I knew I needed to learn more.

You might be familiar with probiotics, the live microorganisms present in yogurt and fermented foods—but have you heard of their counterpart, prebiotics? Despite my interest (read: obsession) with researching health and wellness information, I hadn’t, so I sought out an expert. Here, Rebecca Ditkoff, MPH, RD, a New York City–based registered dietitian and founder of Nutrition by RD, gives a full run-down.

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The Difference Between Probiotics and Prebiotics

There are trillions of bacteria and other microorganisms that take up residence in the lining of the digestive tract and play a key role in our health. Probiotics are one of the most well-known parts of this complex system. "Probiotics are the 'good' bacteria that live in our guts and promote healthy digestion and also give the immune system a boost. Although your digestive tract naturally produces probiotics, it is beneficial to also consume more foods naturally rich in probiotics to increase your levels and variety of strains of the good bacteria," Ditkoff explains. Probiotics have been shown to help balance the microorganisms in the digestive tract and help repopulate the beneficial bacteria after, say, taking a round of antibiotics.

Prebiotics, on the other hand, are types of carbohydrates found in fiber-rich fruits and vegetables that are non-digestible by the body. Instead, they pass through your gut and provide a food source for those healthy bacteria (probiotics) and allow them to thrive. "It’s important to note that all prebiotics are fiber, but not all fiber is prebiotic,” Ditkoff says.

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How Does Your Body Benefit From Both Prebiotics and Probiotics?

"Prebiotics and probiotics play complementary roles for our gut health and work as a team to support your gut microbiome," Ditkoff says. They work together to maintain the balance of healthy bacteria by helping populate the live microorganisms themselves (the probiotics) and feeding those microorganisms (the prebiotics).

Where Can Prebiotics and Probiotics Be Found?

Probiotic-rich foods are often a byproduct of fermentation, which has been used for centuries in many cultures to preserve food and enhance health properties. In recent years, fermented foods have become more popular in the West as health-conscious consumers and practitioners recognize their impact on overall health and especially digestion. You need to look no further than the recent rise in popularity of kombucha and sauerkraut for evidence.

Probiotic-Rich Foods:

  • Kefir, a fermented milk drink similar to yogurt

  • Sauerkraut and kimchi, made by fermenting cabbage and other vegetables

  • Plain live organic yogurt (look for the words “live, active culture”)

  • Fermented soybean products such as tofu, tempeh, and miso

  • Kombucha, a slightly fizzy drink made by fermenting black or green tea

Prebiotics can be naturally found in many fruits, vegetables, whole grains, and legumes that are high in special types of fiber.

Prebiotic-Rich Foods:

  • Alliums, such as garlic, onions, and leeks

  • Asparagus

  • Apples

  • Chicory root

  • Dandelion greens

  • Jerusalem artichokes (aka sunchokes)

  • Slightly under-ripe bananas

Should You Take a Probiotic Supplement?

Many of us are familiar with the boxes and bottles of probiotics sold on drugstore shelves, promising to help with digestive woes. But is it worth the sometimes hefty price tag? Ditkoff says to not be so quick to pull out your wallet.

"In the U.S., probiotics are sold as dietary supplements, which do not undergo the testing and approval process by the FDA," she explains. "Manufacturers are responsible for making sure they're safe before they're marketed and that any claims made on the label are true—however, there is no guarantee that the types of bacteria listed on a label are effective for the condition you're taking them for."

She also mentions that the health benefits of probiotics are strain-specific, and that not all strains are created equal. Consult with your primary care provider or a registered dietitian (RD/RDN) to discuss options and your particular situation before taking a probiotic supplement.

Should You Take a Prebiotic Supplement?

The truth is, research on prebiotic supplements is still in its early stages, and many of the benefits are still largely theoretical. For those reasons, and because potentially helpful prebiotics can be found readily in many fruits and vegetables, it’s best to consume your prebiotics naturally whenever possible.

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