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Explore the differences between prebiotics and probiotics and how both can benefit your gut health.

Daily Nutrition & Health

The Difference Between Prebiotics and Probiotics

Susan Bowerman, M.S., R.D., CSSD, CSOWM, FAND – Sr. Director, Worldwide Nutrition Education and Training April 7, 2024

If your goal is to maintain your overall wellness, taking care of your digestive health should be one of your top priorities since the bacterial environment within your body affects many of your body’s necessary functions that help you thrive and feel your best.

You’ve probably already heard of “prebiotics” and “probiotics” which are both important in supporting the health of your digestive system – particularly that of the microorganisms that live in your gut, also known as the microbiome.

In simple terms, probiotics are the “good” bacteria that keep your body healthy, while prebiotics are the foods that promote their growth. Essentially, you can think of prebiotics as the nutrients probiotics utilize to survive and thrive.

Before we dive into the benefits of both, it helps to understand why these friendly microbes are so important.

What Are Prebiotics?

Broadly speaking, prebiotics are the compounds in many of the high-fiber foods that you eat. While humans lack the ability to break down the certain carbohydrates and fiber that we consume in foods like fruits, vegetables, beans and whole grains, the microbes in your gut are more than happy to do the job for you in a process referred to as fermentation. In fact, probiotics stimulate the growth and activity of the good bacteria in your digestive tract and can improve health.

Of the two general types of fiber – soluble and insoluble – it’s the soluble fibers (found in foods like oats, barley and beans) that are considered to be prebiotic. Not only do they tend to thicken and swell when they come in contact with liquid, making foods tend to be filling, but soluble fibers also encourage the growth of the good bacteria in your digestive tract.

What Are the Benefits of Prebiotics?

Prebiotics serve as food for probiotics, but they potentially can affect other organs and systems in the body. Soluble fibers not only help to fill you up, but they also slow the absorption of sugar into the bloodstream, so they can help to keep blood sugar levels even throughout the day in normal, healthy people. These same fibers can also help keep blood cholesterol levels within a normal range.

In addition, prebiotics:

  • Are broken down by the good bacteria, producing compounds that promote gut health, skin health and immune health
  • May increase calcium absorption
  • May help relieve certain digestive problems


Which Foods Are Rich in Prebiotics?

Prebiotic fiber compounds are particularly abundant in plant foods, especially bananas, onions, garlic, leeks, asparagus, artichokes, tomatoes, plums, apples, nuts, soybeans and whole-wheat foods. But rather than focusing on a short list of fruits and vegetables, it’s wise to consume a wide variety of vegetables, fruits, beans and whole grains to reap the many nutritional benefits they provide.

What Are Probiotics?

The word “probiotic” derives from Greek, meaning “promoting life.” And probiotics certainly do just that in your digestive tract. Probiotics are the “good” bacteria (sometimes called live cultures) that you can consume from foods or supplements. Probiotics are the same bacteria that reside in your gut. Taking in probiotics can help to balance the populations of the various types of bacteria in your gut, which, in turn, promotes gut health.

While the idea of consuming bacteria may not sound appealing, it’s likely that you already consume them without realizing it. Probiotics are found in many fermented foods. Fermentation is a natural process in which bacteria convert sugars and other carbohydrates in foods into acids. That’s why many naturally fermented foods have a tangy taste.

What Are the Benefits of Probiotics?

There are many, many different microbes that live in your gut, and gut health relies on the right balance of the different types. The typical modern diet, with an abundance of sugar and highly processed foods, promotes the growth of certain bacteria that can lead to digestive discomfort – often in the form of bloating or irregularity.

However, a diet rich in prebiotic fibers helps to promote the right balance in the digestive system, and when you consume fermented foods that contain live bacteria, you are introducing beneficial bacteria directly into your digestive tract.

Some benefits of probiotics include:

  • Restoring balance of gut bacteria
  • Promoting regularity
  • Keeping your immune system strong 


What Are Foods Rich in Probiotics?

For many people, the most common source of probiotics is fermented dairy products such as yogurt, kefir and certain aged cheeses. In fact, one of the most common strains of probiotic bacteria that reside in your intestines is Lactobacillus acidophilus, which is found in yogurt.

Beneficial probiotics can also be found in:

  • Fermented vegetables such as pickles, kimchi, olives and sauerkraut (only when sold refrigerated; canned products are heated during processing, which destroys the beneficial bacteria)
  • Fermented soy products such as miso and tempeh 
  • Cultured nondairy yogurts (look for “live active cultures” on the label)
  • Kombucha beverages
  • Other foods to which probiotics have been added, such as cereals or protein bars


Should You Take Prebiotic and Probiotic Supplements?

Let me address some frequently asked questions related to prebiotic and probiotic supplements.

1) Why should someone consider taking prebiotic and probiotic supplements?

Adults should be eating close to 30 grams of fiber a day, but the average grown-up only eats about a third of that. Our busy lifestyles contribute to the problem – when we’re on the go, we’re less likely to eat the high-fiber fruits, vegetables and whole grains that are more typically found at home. So, many of us are lacking when it comes to good sources of prebiotics, and unless you’re a regular consumer of fermented vegetables or dairy products, you might not be getting good sources of probiotics daily either. Fiber supplements that contain both soluble and insoluble fibers, along with probiotic supplements, can help to fill in gaps.

2) How often should you take these supplements? Should I worry about taking too much?

 Supplements should be taken in amounts recommended on the product label and can be used daily. However, when starting a fiber supplement, it’s often a good idea to start with a bit less than recommended and gradually increase the daily dose. That way, your digestive system has a chance to adjust.

3) When is the best time to take prebiotics?When is the best time to take probiotics?

The most important factor in taking supplements is taking them consistently. So, choose a time of day when you will remember to take your supplements.

4) Can I take these supplements together?

While it’s not necessary that you take your prebiotic and probiotic supplements at the same time, it might make it easier to get into the habit if you do. And there’s certainly no reason why you can’t take them at the same time – the combination is known as symbiotic – since one acts as a food source for the other.