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.
Prebiotics are types of fibre that humans cannot digest, but your gut bacteria can. These types of fibre provide nutrients to the bacteria that support healthy digestion and immune function.
Probiotics are beneficial bacteria, and prebiotics are food for these bacteria. We’ll explain what you need to know about the two.
What are probiotics and prebiotics?
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 fibre.
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.
Why are the gut bacteria beneficial?
The good bacteria in your digestive tract help protect you from harmful bacteria and fungi.
A 2013 studyTrusted Source on bacteria in the gut confirms that a wide variety of this good type of bacteria can aid in immune system functions, improve symptoms of depression, and help address obesity, among other benefits (1Trusted Source).
Additionally, some of your gut bacteria form vitamin K and short-chain fatty acids.
Short-chain fatty acids are the main nutrient source of the cells lining the colon. They promote a strong gut barrier that helps keep out harmful substances, viruses, and bacteria. This also helps reduce inflammation and may have the potential to reduce the risk of cancer (2Trusted Source).
How does food affect the gut microbiota?
The food you eat plays an important role in the balance of good and bad gut bacteria.
For example, a high sugar and high fat diet negatively influences the gut bacteria and may contribute to insulin resistance and other conditions (3Trusted Source, 4).
Once you regularly feed the wrong bacteria, they’re able to grow faster and colonize more easily, without as many helpful bacteria to prevent them from doing so (5Trusted Source).
Harmful bacteria and less healthy gut flora has also been associated with higher body mass index (BMI) (6Trusted Source).
Additionally, foods treated with pesticides may have negative effects on the gut bacteria, although more research is needed to confirm this (7, 8Trusted Source).
Studies have also shown that antibiotics can cause permanent changes in certain types of bacteria, especially when taken during childhood and adolescence.
Because antibiotic use is so widespread, researchers are now studying how this may cause health problems in people later in life (9, 10Trusted Source).
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 fibre, but your good gut bacteria can digest them.
Foods that are high in prebiotic fiber include:
legumes, beans, and peas
Jerusalem artichokes (not the same as regular artichokes)
One of the things your good gut bacteria do with prebiotic fibre 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 fibre (11).
Which foods are probiotic?
There are also many probiotic foods that naturally contain helpful bacteria, such as yogurt or kefir (water or diary)
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:
kefir (water or diary)
some types of pickles (unpasteurised)
other pickled vegetables (unpasteurised)
If you’re going to eat fermented foods for their probiotic benefits, make sure they’re not pasteurised, 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
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.
Talk to your healthcare provider to make sure you’re eating the right amounts of each. It’s possible to go overboard or have side effects.
To see if you could benefit from a supplement, check out the World Gastroenterology Organization Global Guidelines list of evidence-based conditions that probiotics could potentially help. It also includes recommendations.