If you are what you eat, then you are also what your gut bacteria eat: Every time you chow down on a juicy burger or crunch on a kale salad, you’re also passing fuel their way. But just like humans, these microbes don’t all have the same food preferences. Probiotics (a.k.a. the good bacteria in your body), in particular, crave prebiotics, or specific compounds found in a variety of fiber-rich foods. The more of them you consume, the more these beneficial bugs can flourish—which only means good things for you, their generous host.
In fact, that positive effect is in the definition of a prebiotic, which was revised in 2016 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to be “a substrate that is selectively utilized by host microorganisms conferring a health benefit.” That substance is usually a kind of fiber—because fiber can’t be digested well by your stomach, it can make it to your colon largely unscathed, where your probiotics can enjoy it. But science is now discovering that other nutrients, like the polyphenols (a type of antioxidant) in cacao, may also have prebiotic-like effects, Vanessa King, MS, RDN, Honolulu-based registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics, tells SELF.
Once your good gut bacteria get ahold of prebiotics, they can proliferate, which leaves your colon teeming with supportive microbes—and keeps the bad bacteria (their disease-promoting nemeses) at bay, King says. The result? A diverse, balanced microbiome.
Read on to learn all the reasons you should be feeding your gut flora a hefty dose of prebiotic-rich foods, a list of the best ones, and how to work them into your diet.
Why are prebiotics so good for you?
These substances set off a beneficial ripple effect: When probiotics ferment prebiotics, they create short-chain fatty acids (SCFAs), which are important for the health of the cells lining your GI tract, Gail Hecht, MD, Chicago-based gastroenterologist and medical expert at Wonderbelly, tells SELF. When that intestinal barrier is strong, fewer pathogens from your gut can seep through it and infect your body—meaning, your immune system will have less to deal with.
SCFAs might also tamp down inflammation in your gut, which is linked with a lower risk of certain chronic conditions, like type 2 diabetes or cancer. For the same reason, prebiotics may aid in reducing symptoms in folks with inflammatory bowel diseases like Crohn’s and ulcerative colitis.
In the shorter term, eating more prebiotics can also help you poop more regularly and comfortably—again, they’re typically a form of fiber, which helps move things along, Cara Harbstreet, RDN, Kansas City–based registered dietitian and owner of Street Smart Nutrition, tells SELF. In a similar realm, prebiotic-rich foods can keep you feeling full for longer and regulate your blood sugar post-meal, King adds.
How many prebiotics should you aim to eat?
There isn’t a universal dietary guideline for prebiotics (and quantities aren’t labeled on food products), but based on evolving research, ISAPP suggests a target of five grams per day to reap the benefits. For the average person, aiming for the USDA benchmark of roughly 28 grams of fiber a day is an easy way to hit that prebiotic quota (and then some). But it’s worth noting that most Americans are getting roughly half the fiber they should be eating, Harbstreet says, so there’s a good chance you could benefit from some more roughage in your life.
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