Chances are you’ve heard of probiotics: microorganisms found in yogurt and other fermented foods and supplements that are touted for their ability to help the gut stay healthy. But the precursor to probiotics, called prebiotics, may be the next big thing in eating healthy. 

The human body is made up of trillions of microorganisms. According to the National Institutes of Health, a 200-pound adult has between two and six pounds of bacteria in their body, which play an important role. A large number of those bacteria—called gut microbiota—live in the digestive tract. They help you digest food, help produce vitamins and boost your immune system. Gut microbiota need their own food source in order to multiply and keep you healthy. That’s where prebiotics come in.

Prebiotics are a form of fiber that act as a source of nourishment for gut microbiota. They do this through the process of fermentation. Prebiotics are found naturally in some foods: wheat products, asparagus, milk, onions, bananas and garlic are just a few examples. Many foods don’t have a lot of prebiotics, but you can increase your levels by taking a dietary supplement.

Prebiotics are able to change your gut microbiota in various ways:

• Certain kinds of gut microbiota can only ferment a specific type of prebiotic, while others can ferment multiple types. That’s why it’s a good idea to consume a mix of different prebiotics—through a varied diet—to increase the amount of beneficial gut microbiota in your digestive system.
• Fermentation of prebiotics by some kinds of bacteria can produce molecules for other groups of bacteria to feed on.
• Fermentation makes the stomach more acidic, which can then promote the growth of gut microbiota that are sensitive to acidic environments.

To qualify as prebiotics, foods should be able to do three things: withstand the acidity of the stomach, be fermented by intestinal microbes and promote the activity and growth of probiotics to improve health. Prebiotics have been found to improve gastrointestinal diseases such as irritable bowel syndrome and Crohn’s disease. They have also been shown to reduce the growth of colorectal cancer cells, stimulate the immune system to fight off infection, improve brain health and lower the risk of heart disease. Added bonus: Prebiotics do not have any dangerous or severe side effects. So, add some prebiotic fiber to your diet today!