Probiotics and Prebiotics: What's the Difference?

Probiotics and prebiotics are both pretty big topics in nutrition these days. Yet even though they sound similar, the two play different roles in your health.

Probiotics are beneficial bacteria, and prebiotics are food for these bacteria. We’ll explain what you need to know about the two.

Our bodies contain just as many microbial cells as they do human cells, if not more - and most of these microbes are located in our gut. So what are probiotics and prebiotics, and how can they help maintain gut health?

Both prebiotics and probiotics are important for human health. However, they have different roles:

Probiotics. These are live bacteria found in certain foods or supplements. They can provide numerous health benefits.
Prebiotics. These substances come from types of carbs (mostly fiber) that humans can’t digest. The beneficial bacteria in your gut eat this fiber.
The gut bacteria, collectively referred to as the gut flora, or gut microbiota, perform many important functions in the body.

Eating balanced amounts of both probiotics and prebiotics can help ensure that you have the right balance of these bacteria to keep your gut microbiota healthy.


Probiotics are live microorganisms, often bacteria or yeasts, that benefit our gut health when consumed in our food. These microbes, whether acquired naturally from food or from probiotic supplements, settle along the gut. From there, they assist the digestion of components in our foods which our own cells find difficult to break down. 

Bifidobacteria, for example, are one of the first strains of bacteria to colonise the gut after birth.2 These bacteria then support the growth of  a range of other microbes, which together strengthen the gut’s structure for nutrient absorption and also create a protective barrier, outcompeting disease-causing strain to reduce the chance of a gut infection. Throughout this struggle for survival, the beneficial microbes in our gut need to fuel themselves - which is where prebiotics come in. 


There are certain parts of our food which we can’t digest, but that can be fermented and used as fuel by the microbes in our gut. These parts of our food are known as prebiotics (or, fibre). Prebiotics provide microbes with the resources they need to grow and establish themselves in the gut3 - but crucially, prebiotics preferentially encourage the growth of microbes that are beneficial for our health over those that cause disease.

Which foods are prebiotic?
Before you go out and buy expensive prebiotic supplements, remember that many foods naturally contain them.

That’s because prebiotics are types of fiber found in vegetables, fruits, and legumes.

Humans are not able to digest these types of fiber, but your good gut bacteria can digest them.

Foods that are high in prebiotic fiber include:

  • legumes, beans, and peas
  • oats
  • bananas
  • berries
  • Jerusalem artichokes (not the same as regular artichokes)
  • asparagus
  • dandelion greens
  • garlic
  • leeks
  • onions

One of the things your good gut bacteria do with prebiotic fiber is turn it into a short-chain fatty acid called butyrate.

Studies suggest that butyrate production in the colon cannot be maintained without adequate intake of prebiotic fiber.

Which foods are probiotic?
There are also many probiotic foods that naturally contain helpful bacteria, such as yogurt.

A high quality, plain yogurt with live cultures can be a fantastic addition to your diet if you want to add beneficial bacteria.

Fermented foods are another great option, as they contain beneficial bacteria that thrive on the naturally occurring sugar or fiber in the food.

Examples of fermented foods include:

  • sauerkraut
  • kimchi
  • kombucha tea
  • kefir (dairy and nondairy)
  • some types of pickles (unpasteurized)
  • other pickled vegetables (unpasteurized)

If you’re going to eat fermented foods for their probiotic benefits, make sure they’re not pasteurized, as this process kills the bacteria.

Some of those foods can also be considered synbiotic, because they contain both beneficial bacteria and a prebiotic source of fiber for the bacteria to feed on.

Some examples of synbiotic foods are cheese, kefir, and sauerkraut.

The bottom line of this is Keeping your gut bacteria balanced is important for many aspects of health.

To do this, eat plenty of both prebiotic and probiotic foods, as they will help promote the most ideal balance between good and bad gut bacteria.

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