Nutritional Supplements

Probiotics and Prebiotics: What’s the Difference?

You’ve probably heard that these microorganisms and compounds in food and supplements are good for you. But how do they work, and how can you optimize their potential health benefits?
Probiotics and Prebiotics: What’s the Difference?
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Published on May 21, 2024
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You’ve probably seen food and supplement products tout their “probiotics” and “prebiotics.” But what exactly are these ingredients, and how do they work to improve our health?

More importantly, should you try to get more probiotics and prebiotics into your diet (and what’s the best way to do it)? Here’s what to know about probiotics and prebiotics, and how to unlock their potential benefits.

What Are Probiotics?

Probiotics contain microorganisms that may benefit the health of our microbiome — groups of microorganisms (fungi, bacteria, and viruses) that live in a particular part of the body, such as the skin or gastrointestinal (GI) tract. A healthy microbiome can have a positive impact on our overall health.

Probiotics can be found in various foods, such as yogurt and kombucha.

What Are Prebiotics?

Prebiotics are components in some foods that act as nutrition for the microorganisms, including probiotics, that make up our microbiome.

You can get prebiotics from food and supplements, but they are not microorganisms. Rather, they are components in certain foods that act as nutrients for the beneficial microbes already in your body, in places like the colon, says Mary Ellen Sanders, PhD, a food science microbiologist in Centennial, Colorado, and the executive science officer for the International Scientific Association for Probiotics and Prebiotics (ISAPP).

Prebiotics basically support healthy microorganisms, such as probiotics, by providing them with nutrients to help them thrive, and this in turn supports the health of your microbiome.

What Are the Benefits of Probiotics Versus Prebiotics?

In the broadest sense, probiotics are beneficial bacteria, says the microbiologist M. Andrea Azcarate-Peril, PhD, a professor of medicine in the school of medicine at the University of North Carolina in Chapel Hill, where she runs the Microbiome Core Facility.

That means that these live microorganisms can help your body when they’re ingested in recommended amounts through food or, in some cases, supplements.

There are many types of microbes that live in different parts of our bodies, including the gut, mouth, stomach, vagina, urinary tract, and more. Their key functions include:

  • Treatment or prevention of dysbiosis, an imbalance or deficit of beneficial microorganisms, notes Cleveland Clinic

  • Production of beneficial substances, such as vitamins, per the National Center for Complementary and Integrative Health

  • Digestion

  • Support for the immune system through elimination of harmful microorganisms that cause illness or infection

Looking for prebiotics but don't know where to start? We asked Registered Dietitians to help us pick the 10 best prebiotics for women.

Probiotics may be associated with an array of health benefits. For example, some of these types of beneficial bacteria fight off more harmful bacteria, and may help prevent or resolve infections, including atopic dermatitis (eczema) and acne, cavities and gum disease, urinary tract infections (UTIs), and antibiotic-related diarrhea.

In addition, probiotics help maintain a healthy community of microorganisms in the GI tract, which may influence health inside and outside the gut. Some research suggests that a healthy gut microbiome can impact mood, pain tolerance, mental acuity, inflammation, and metabolism.
But while the evidence found so far on the health benefits of probiotics is promising, there’s still a lot that needs to be investigated further, including which probiotics are helpful and which are not; how much people would need to ingest to get health benefits; or which individuals might benefit the most.

Prebiotics can help the body in a number of ways. They:

  • Regulate bowel movements
  • Produce brain chemicals known as neurotransmitters, which affect mood and other functions
  • Improve immune function
  • Fight inflammation
  • Help your body absorb vitamins and minerals
One review, which assessed research on the health effects of prebiotics, found evidence that prebiotics play a role in improving symptoms or quality of life in people with certain conditions, such as IBD (inflammatory bowel disease), osteoporosis, diabetes, and anxiety.

What Are Different Food Sources of Probiotics Versus Prebiotics?

Probiotics are naturally found in fermented foods and drinks, including:

  • Yogurt and kefir
  • Kombucha
  • Sauerkraut or kimchi
  • Pickles
  • Cottage cheese
  • Miso
But fermented foods that have gone through processing beyond fermentation, such as pasteurization, baking, or smoking, likely no longer contain beneficial microbes.

Meanwhile, prebiotics are typically found in foods that contain certain types of fiber, including resistant starch (a fiber-like carbohydrate that resists digestion), inulin (contained in plants), and pectin (found in fruits). Foods that provide these fibers are:

  • Boiled potatoes
  • Green bananas
  • Beans
  • Onions
  • Barley
  • Leeks
  • Soybeans
  • Garlic
  • Asparagus
  • Apples
  • Peaches
  • Raspberries
  • Tomatoes

Probiotics and prebiotics are also available as supplements.

How Do You Know if You Need to Take Probiotics or Prebiotics in Supplement Form?

It’s best to get probiotics and prebiotics from food, because that way you also get helpful nutrients. But certain people may benefit from supplements.

Your doctor may recommend a probiotic supplement as a preventive measure if you have a history of infections (like UTIs) or if you’ve recently had an illness or treatment that affected your microbiome.

 Antibiotics, for example, decrease the diversity of bacteria in your body (known as dysbiosis) and often cause diarrhea. A probiotic supplement may restore a healthy balance of microorganisms and reduce diarrhea risk.

People with ulcerative colitis (UC), a type of inflammatory bowel disease, may benefit from using probiotics in addition to conventional treatment.

 It’s best to check with your doctor before adding a probiotic supplement to your UC treatment plan.
Probiotics may also improve common GI symptoms, such as gas, bloating, and constipation, but more studies are needed to determine if they’re safe and effective for older adults.

People with allergies or food intolerances should use probiotic supplements with caution, as some may contain ingredients (such as dairy or eggs) that cause reactions.

Meanwhile, prebiotics can be found in many high-fiber foods, so you may not need a supplement unless your diet is lacking in fruits and vegetables.

 
People with bloating issues, such as those with small intestine bacterial overgrowth (SIBO), may want to avoid prebiotic supplements, as the additional fiber can worsen symptoms.

 
A synbiotic, which is a supplement that combines a prebiotic and a probiotic, may help your body absorb the probiotic more effectively.

 Research suggests that synbiotics may balance gut microbiota and boost immune ability.

 But the prebiotics in the supplement can cause gas and bloating in some people.

Keep in mind that dietary supplements are not regulated by the U.S. Food and Drug Administration (FDA) in the same way conventional medications are, which is why it’s crucial to consult a doctor or registered dietitian-nutritionist before taking any probiotic or prebiotic supplements, especially if you have an underlying condition.

The Takeaway

Probiotics are microorganisms that may benefit gut health and more. Meanwhile, probiotics serve as nutrition and support for probiotics and are also associated with possible health benefits, including improved immune system function and overall health. If you’re interested in taking probiotics and prebiotics in supplement form, talk to your healthcare team, especially if you are managing a chronic health condition or taking medication to treat an illness.

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Rabia de Latour, MD

Medical Reviewer
Rabia de Latour, MD, is a therapeutic endoscopist and gastroenterologist at NYU Grossman School of Medicine, where she serves as the director of endoscopy and chief sustainability officer at Bellevue Hospital. She is the host of Sirius XM Doctor Radio Internal Medicine Show.
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Michele W. Berger

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Michele W. Berger is a writer and editor with more than 15 years of experience covering science, the environment, and healthcare. She has contributed to publications including Scientific American, Audubon magazine, The Weather Channel, and Health Leaders magazine, among others. She has a master’s degree from Columbia School of Journalism.
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