What's the Difference Between Prebiotics and Probiotics?

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Prebiotics and probiotics are both essential for gut health. Each plays a role in keeping your digestive system working smoothly. While probiotics are live strains of bacteria, prebiotics are the plant fibers that feed them and keep populations thriving.

Probiotics and prebiotics are available through supplements and food. Getting enough of both can support the health and function of your digestion, immune system, nutrient uptake, and more.

What Are Probiotics?

Probiotics are strains of living bacterias and yeasts that live primarily in your intestines but also in your mouth, urinary tract, vagina, lungs, and on your skin. Several types of probiotics live in different areas of your body, but the most common are the bacterias lactobacillus and bifidobacterium and the yeast saccharomyces boulardii.

Probiotics are partly responsible for the health of your intestinal microbiome. These living organisms are always naturally present in your body, both good and bad. Beneficial bacterias and yeasts are called probiotics and help rid your body of harmful bacterias and yeasts to keep your digestive system functioning correctly.

What Are Prebiotics?

Prebiotics are non-digestible parts of plant food that help feed probiotic populations. Humans don't possess the enzymes required to break these plant parts down for absorption. Instead, the bacterias in your gut break them down for energy, spurring reproduction and producing by-products that have potentially beneficial health effects.

Common prebiotics include:

  • Fructans (inulin and fructooligosaccharides)
  • Galactooligosaccharides (GOS)
  • Oligofructose (fructose)
  • Resistant starch

Prebiotics ferment in the gut to produce short-chain-fatty acids that have several beneficial effects. Inulin and oligofructose, which are fructans, are believed to be the most effective in boosting the most species of probiotics.

The Benefits of Probiotics

Probiotics are partly responsible for the health of your intestinal microbiome. They help your intestines uptake nutrients and reduce the risks of some diseases and infections. Probiotics boost your immune system and general health, especially that of your digestive system. 

Research has shown that probiotics are effective in treating irritable bowel syndrome, enteritis, bacterial infections, and other gastrointestinal disorders and may have additional benefits for those with lactose intolerance and in the treatment of atopic dermatitis. Further research is being done on the potential benefits of probiotics for cancer prevention and treatment.

The Benefits of Prebiotics

Prebiotics help feed the beneficial bacterias and yeasts in your gut and promote a healthy environment for the beneficial organisms to live in. The fermentation process of prebiotics that occurs in the gut helps to stimulate the immune system to fight pathogens.

Prebiotics are also thought to help increase absorption of some minerals, such as calcium, lower your risk of allergies, and aid in metabolic functioning. Other studies have shown that the daily intake of 12 grams of inulin for one month reduced blood levels of very-low-density lipoprotein (VDL), which is considered “bad” cholesterol.

There is no formal recommendation for how much probiotic or prebiotic foods or supplements to consume daily. As a result, try to include a wide variety of prebiotic and probiotic food sources in your diet and look to supplements as indicated by a healthcare professional.

Food Sources

Consuming a wide variety of both probiotic and prebiotic foods may help you maintain a healthy gut microbiome. Look for foods with multiple live strains and that do not contain added sugars.

Probiotic-Rich Foods

Food sources of probiotics are mainly fermented foods and drinks that contain living organisms. These foods include:

Prebiotic-Rich Foods

Prebiotics are obtained from plant sources and come mainly from carbohydrates in foods such as:

Prebiotics are also often added to other foods, such as protein bars, in the form of inulin.


Supplements may help you obtain adequate amounts of prebiotics and probiotics to achieve a healthy gut microbiome when food isn’t enough. As well, if you have been prescribed antibiotics, taking probiotics may help with some of the negative symptoms, such as diarrhea.

Probiotic Supplements

Usually, probiotic supplements provide multiple strains of bacterias measured in colony-forming units (CFU). The CFU counts can range from 1 to 50 billion or more, but the higher CFU does not necessarily indicate a better product.

When choosing a probiotic supplement, check for the estimated live cultures at the end of the shelf life rather than at the time of manufacture. There are seven main bacterial strains found commonly in supplements:

  • Lactobacillus
  • Bifidobacterium
  • Saccharomyces
  • Streptococcus
  • Enterococcus
  • Escherichia
  • Bacillus

Prebiotic Supplements

Prebiotic supplements are available in several forms, such as chicory root fiber, resistant starches like potato starch, and pectin from apples. The research is mixed on whether or not supplementation can help increase beneficial bacteria or help with conditions such as Crohn's Disease or irritable bowel syndrome (IBS). Still, there is promising evidence that it can protect against colorectal cancer and prevent its progression.

When choosing a prebiotic supplement, the National Institutes of Health (NIH) recommends that you check the Supplement Facts label on the product you choose. Reading this label will let you know the amount of fiber per serving and whether ingredients like fillers, binders, and flavorings have been added.

Although probiotics and prebiotics supplements are recognized as safe, they are not regulated as drugs by the U.S. Food and Drug Administration; therefore, there is no guarantee of their safety. Some common side effects of probiotics and prebiotics include gas, bloating, and other gastrointestinal issues.

A Word From Verywell

Probiotics and prebiotics occur naturally in certain foods and can contribute to a healthy gut microbiome, improve digestion, and possibly boost immunity. Eating plenty of fermented foods and plants that contain prebiotic fiber is an excellent choice to reap these benefits. If you feel that supplementation is right for you, there are plenty of options on the market. Speak to a healthcare provider if you have any concerns about your gut health or taking these supplements.

11 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Rachel MacPherson, BA, CPT
Rachel MacPherson is a health writer, certified personal trainer, and exercise nutrition coach based in Montreal.