Similar to probiotics, the field of prebiotics has evolved in recent decades. The first formal definition of prebiotics was established approximately 30 years ago. At the time, scientists described “nondigestible food components” that help the host by “stimulating the growth and/or activity” of bacteria already present in the colon.
The research community currently defines these as “substrates that are selectively utilized by host microorganisms and confer health benefits.” In other words, prebiotics are the substrate and nutrient source for microorganisms such as probiotics. “In layman’s terms, you can think of prebiotics as food for the beneficial microorganisms in your body,” says Saunders. “It doesn’t have to be just in the gut.”
Prebiotics can help the body in a variety of ways. For example, one review found evidence that a prebiotic called galactooligosaccharides may improve the body’s ability to absorb iron.
Another review evaluating research on the health effects of prebiotics found that prebiotics can improve symptoms and quality of life for certain conditions such as IBD (inflammatory bowel disease), osteoporosis, diabetes, and anxiety. We found evidence that it may play a role. The review also found that in obese patients, prebiotics can lower cortisol levels, improve sleep, and significantly reduce triglyceride levels and waist and hip size.
These compounds occur naturally in many common foods, including garlic, onions, Jerusalem artichokes and bananas, Sanders says. “The problem is that it’s difficult to eat a banana and get what we think is an effective amount.”
If you don’t take enough, you may not get the desired effect, but if you take too much, such as through supplements, problems may occur. “Doses that are too high can cause gastrointestinal discomfort, leading to gas and bloating,” Dr. Saunders explains. “You want to make sure you’re getting the right dose. What researchers often say is try to get at least 5 grams of prebiotics in your diet each day.”
Also, if you’re checking labels, note that the word “prebiotic” rarely appears. Instead, you may see terms such as “galactooligosaccharides,” “fructooligosaccharides,” “oligofructose,” “chicory fiber,” or “inulin,” which are common groups of prebiotics.
