What Are Prebiotics & Probiotics? - Role in the GI Tract

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  • 0:01 Human Gut Microbiome
  • 0:52 GI Tract
  • 2:10 Probiotics
  • 3:10 Prebiotics
  • 4:10 Lesson Summary
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Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Prebiotics and probiotics help grow the community of beneficial bacteria living in the GI tract. These bacteria promote colon health and contribute to your overall well-being. Learn how prebiotics and probiotics are obtained and how they benefit you.

Human Gut Microbiome

If you have a garden, you know that you need to plant seeds and provide an environment that allows those seeds to grow. If you want your garden to flourish, you can add some fertilizer and make sure the weeds are pulled. Well, the garden growing in your backyard is very similar to the human gut microbiome that is alive and growing inside your gastrointestinal (GI) tract. The human gut microbiome, also referred to as the gut microflora, is the community of bacteria that live in your digestive tract. These bacteria are like the seeds of your garden. As they grow, they provide benefits to both your colon and your overall health. To help them grow and flourish, you can consume probiotics and prebiotics. In this lesson, we will learn about these substances and how they benefit you.

GI Tract

Before we jump into a discussion of probiotics and prebiotics, it will be good to get a refresher of some important facts about the GI tract. For a long time, the scientific community overlooked the role the GI tract plays in our overall health. However, it's now known that the GI tract, and, in particular, the colon, is vital to your well-being. This is thanks to the community of bacteria that call the colon home. The gut microbiome is teeming with billions of beneficial bacteria. Even though we have been trained to think of bacteria as bad, in the gut, there are thousands of species of good bacteria that are welcomed guests. In fact, the more the better!

These bacteria are able to make vitamins, like vitamin K and many B vitamins. They also break down undigested carbohydrates. This break down process produces important byproducts called short-chain fatty acids. Many of these fatty acids are used by the colon cells, which supports colon health. Others are sent into the bloodstream where they are thought to play a role in immunity.


Probiotics can be added to your diet to increase the number of beneficial bacteria in your gut microbiome. Probiotics are live bacteria that are consumed in foods like yogurt or other dairy products or taken as a supplement. These live bacteria join the existing community of bacteria in the colon. If good bacteria are lost due to actions, such as taking antibiotics, probiotics can be consumed to replenish the microbiome. In a way, we could think of adding probiotics to your diet as adding seeds to your garden. The more you have, the better off you are.

It's also thought that probiotics may be able to inhibit the growth of bad bacteria. So, we could say that probiotics are able to keep the weeds out of your intestinal garden. This help to keep a balance between the good and bad bacteria of the colon.

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