You have probably seen "probiotic" on yogurt, kombucha and pickle jars. Its lesser-known partner, the prebiotic, gets far less attention, even though it does a lot of the work of keeping your gut bacteria fed. Here is what prebiotics are, where to find them, and how they work with probiotics.
What is a prebiotic?
An international panel of scientists defines a prebiotic as a substrate that is selectively utilized by host microorganisms conferring a health benefit. In plain terms: something your body does not digest itself, but that your beneficial gut bacteria can use as food, with a measurable upside for you.
Most prebiotics are types of fiber. Compounds such as inulin and other oligosaccharides resist digestion in the small intestine and reach the colon, where gut bacteria ferment them. That fermentation encourages the growth of helpful groups like Bifidobacterium.
How are prebiotics different from probiotics?
Probiotics are live microorganisms that provide a health benefit when taken in adequate amounts. Prebiotics are not alive; they are the fuel. One way to picture it: probiotics are the seeds, prebiotics are the fertilizer.
Probiotics are delicate. Heat and stomach acid can reduce how many survive the trip through your digestive system, which is why strain choice and how you take them matter (see How & When to Take Your Probiotic). Prebiotics help the beneficial bacteria that do arrive, and the ones already living in your gut, to thrive.
Which foods contain prebiotics?
Many everyday plant foods contain prebiotic fibers. Inulin and oligofructose are found in foods such as chicory root, Jerusalem artichoke (also called sunchoke), onions, garlic, leeks and asparagus, and research has found prebiotic effects for banana, whole grain wheat and whole grain corn, among others.
A simple rule of thumb: the more varied the fiber-rich plants on your plate, the more your gut bacteria have to work with. Our article on why fiber deserves more attention makes the case.
How do prebiotics and probiotics work together?
A product that combines live microorganisms with a substrate they can use is called a synbiotic. Scientists recently updated the definition of a synbiotic to "a mixture comprising live microorganisms and substrate(s) selectively utilized by host microorganisms that confers a health benefit on the host."
It is worth being precise about what the research shows. Probiotics have the stronger evidence for many benefits; in a meta-analysis of controlled trials on mood, for example, probiotics had small but significant effects on depression and anxiety, while prebiotics alone did not differ from placebo. Prebiotics are best thought of as support for beneficial bacteria rather than a stand-alone fix.
Should you choose a probiotic with prebiotics?
Pairing the two is a convenient way to give your probiotic a head start, especially if your diet is light on fiber. Both Trust Your Gut Probiotic + Prebiotic Daily Essential capsules and Trust Your Gut powder pair their probiotic strains with a prebiotic from organic Jerusalem artichoke, one of the inulin-rich foods above, and Trust Your Gut is non-GMO. Food still matters most: eat a variety of fiber-rich plants and add fermented foods where you enjoy them.
If you are new to fiber or prebiotic supplements, increase gradually; a sudden jump can cause temporary gas and bloating. For more on what to expect, read Taking a Probiotic for the First Time.
