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What is the Difference Between Prebiotics and Probiotics?

Have you ever asked yourself this common question? If so, you are not alone, as many people get these two confused.

As the importance of gut health becomes more understood, it’s common to see headlines about the gut-brain connection, prebiotics and probiotics on magazine covers, the evening news and as the topic of many conversations.

Have you found yourself thinking “What exactly is the difference between prebiotics and probiotics”? Let’s put that question to rest once and for all and keep it super simple to understand!

What is a Prebiotic?

Simply defined, a prebiotic is a plant-based food with insoluble fiber components that promotes the growth of beneficial bacteria in your gut (1).

Benefits of Prebiotics

One of the main benefits of prebiotics is that they stimulate the growth of probiotics in the colon after fermentation. The insoluble-fiber components of prebiotics are not broken-down during digestion; therefore, they ferment in the colon, creating a breeding ground for the “good” bacteria that is present (1).


Short chain fatty acids (SCFA) are produced in the gut from the fermentation of prebiotics by gut bacteria. Why is this important? SCFA’s serve as an energy source, inhibit growth of pathogens, reduce the risk of colon cancer, promote bowel motility, and have anti-inflammatory properties (5). Yes please!

Infographic with pictures of food that are prebiotics, such as artichokes, green bananas, onions, apples, asparagus, oats, leeks and garlic.
Plant-Based Prebiotic Sources

Sources of Prebiotics

Prebiotics in Food

Prebiotics are present in many common foods that you likely already eat, such as apples, green bananas, chia seeds, garlic, onions, artichokes, flaxseeds, wheat bran and leeks. If you don’t already have these foods in your diet, aim to start incorporating them on a daily basis.

Prebiotics in Supplements

If you find it hard to get enough prebiotics in your diet, you may need to include a prebiotic supplement. Prebiotic supplements come in both powder and capsule form. You may like to learn more about the 7 Best Prebiotic Supplements of 2021, According to a Dietitian for more guidance.

Side Effects of Prebiotics

Prebiotics are relatively safe to consume with very little risk of side effects. The most common side effects may include gas, cramping, abdominal pain and bloating.


The recommended amount of fiber adults should consume daily ranges from 25 – 35 grams minimum, according to the Academy of Nutrition and Dietetics (AND) In general, any time you are increasing the amount of fiber in your diet, you should do so gradually.

The same advice is followed when you increase prebiotic containing foods in your diet. It may be helpful to know that you should increase your water intake at the same time, so you do not become constipated. If you already consume adequate amounts of water, this may not be necessary.

The AND recommends about 9 cups of unsweetened, un-caffeinated fluids per day for women and about 12.5 cups for men.

What is a Probiotic?

In 2014, the definition of probiotics was formally established by the International Scientific Association for Probiotics and Prebiotics (ISAPP) as “Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”. 

Simply, probiotics are “good” bacteria that provide health benefits when consumed (1).

Benefits of Probiotics

The benefits of probiotics vary depending on the type of probiotic you choose. Probiotics are strain specific, so it’s important to choose the appropriate genus, species and strain when starting a probiotic.

Have you ever asked yourself “How long does it takes for probiotics to work?” The amount of time it takes for probiotics to begin providing benefits depends on various factors as well, such as the health of your gut, the type and strength of your probiotic, and the type of changes you are seeking.

Probiotics are commonly used as a preventative measure to prime the immune system, prevent traveler’s diarrhea, improve irritable bowel, promote weight maintenance, heart health and overall wellness (2).

A multitude of studies demonstrate that stress brought on by physical or psychological factors may be a direct cause of an imbalance of the microbiota-brain-gut axis. This supports the idea that probiotic supplementation or consumption plays a role in improving mental wellness (3).

Sources of Probiotics

Probiotics in Food

Most probiotics are found in fermented foods, although not all fermented foods contain these beneficial bacteria. Examples of these probiotic containing fermented foods include yogurt, sauerkraut, kefir, pickles, miso, kombucha, tempeh, kimchi, and various cheeses. 

Pictures of foods that contain probiotics. Yogurt, kimchi, kombucha, sauerkraut, kefir, tempeh
Probiotics In Food

Probiotics in Supplements

When looking to improve specific symptoms or achieve a specific result, probiotic supplementation is more targeted and individualized to each person’s needs. Probiotic supplementation comes in various forms, including powders, capsules, tablets, liquids and sachets. 

Picture of the different forms probiotic supplements come in. Capsules, Saches, Liquids, Powders.
Probiotics in Supplements

Side Effects of Probiotics

Probiotics, generally recognized as safe, provide greater benefits than risks in most individuals. People with severely compromised immune systems should not take a probiotic without first seeking medical advice, as probiotics may lead to more serious complications.

Most individuals tolerate probiotics without experiencing side effects. If you tend to have a sensitive stomach, start your probiotic regimen slowly and increase to the full dose as tolerated. A probiotic with 10 Colony Forming Units (CFU) or less will be easy to tolerate when first starting on a probiotic supplement (4).

What is the Difference Between Prebiotics and Probiotics?

Now what you’ve been waiting for…the difference between prebiotics and probiotics! I love a good analogy, so let’s insert one here.

Think of a probiotic as a beautiful plant that provides benefits to the other plants in your garden. The prebiotic is fresh water and natural fertilizer that is fed to your plant daily to help it grow, flourish and produce more beautiful plants. As you nourish the plants with the water and fertilizer, the whole garden becomes healthier and healthier.

This is exactly how our gut health and microbiome flourish to help us become healthier mentally, physically and emotionally! We consume probiotics (the good bacteria) and feed them with prebiotics (the insoluble fibers that ferment and allow the probiotics to multiply) and provide greater and greater benefit to the health of the host (our body).

Garden Analogy of how prebiotics feed the good bacteria (probiotics) in our gut.
Garden Analogy

Beyond the Difference Between Prebiotics and Probiotics

Now that we’ve established the difference between prebiotics and probiotics, I think it’s important to recognize how both prebiotics and probiotics work together to support our bodies. 


Synbiotics are supplements that contain a combination of both probiotics and prebiotics, which improve the survival rate of the live organism (1). In order for this combination to work synergistically together, the prebiotic compound must favor the probiotic organism. Think of it using the analogy above. Your healthy plant comes packaged with the fertilizer that best matches the needs of your plant to grow strong and healthy.


Prebiotics and probiotics have more differences than they do similarities, however one thing that they have in common is that they both bring a plethora of benefits to our bodies. They work together, synergistically, to help us thrive.

When choosing prebiotic and probiotic supplements you need to choose a prebiotic compound that is compatible with the probiotic you are taking. You may need to work with a Registered Dietitian that has experience in this area or purchase supplements from a trusted source with high quality, 3rd party testing to ensure you are getting what you pay for.

Both prebiotics and probiotics are generally safe to consume. If you have questions or concerns, seek advice from a medical provider with experience and knowledge in this area prior to starting a new regimen.

The purpose of this information is to inform and empower the reader to make positive lifestyle changes. The intent is not to replace medical advice or instructions given by your doctor or healthcare provider.

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