Resistant Starch Is the Carb You Need for Better Gut Health and Digestion

Fiber has a ton of GI clout—gastroenterologists regularly praise the nutrient for its ability to keep you regular, nourish your microbiome (the community of bacteria in your gut), and even spark other benefits body-wide. Its fellow carbohydrate starch, by contrast, doesn’t have quite the same aura. It usually gets digested more swiftly in your bowel than fiber, breaking down into glucose (a.k.a. sugar) for energy…and offering less GI support. But as it turns out, not all starches are created equal. Resistant starch is a gut-loving type that functions much like fiber in your system and delivers plenty of its upsides to boot.

As its name suggests, resistant starch is a kind of starch, or string of glucose molecules, that resists digestion. Unlike other starches, it’s composed in a way that makes it tough for the enzymes in your small intestine to process and absorb it. That’s the reason it’s often considered a type of fiber instead: Like the GI darling, resistant starch winds its way to your large intestine, or colon, practically intact, setting off a similarly positive ripple effect for your gut and overall health.

The coolest thing about resistant starch is that, while it can be found naturally in some foods that also contain fiber (like oats and legumes), you can also create it in refined grains like white pasta and white rice by preparing them in a certain way. All you have to do is cook and then fully cool them before eating. Refrigeration causes “retrogradation, or a rearrangement of the starch molecules [in these foods] that results in a resistant starch,” Bridgette de Juan, RDN, lead registered dietitian at Orlando Health, tells SELF. So while these foods have had much of their fiber stripped out in processing, you can essentially turn them back into a fiber source (and reap the benefits) by transforming them into more resistant starches. Even better, they also don’t have to be cold when you eat them. Once those starch molecules change structure and get more resistant via cooling, they tend to stay that way even after reheating the food, de Juan explains.

Read on to learn why upping your intake of resistant starch can be a boon for your gut and beyond and exactly how to get more of this good stuff into your diet.

What are the benefits of resistant starch for your gut and overall health?

The digestive perks spring mainly from how this starch moves through your small intestine relatively unscathed. Like insoluble fiber, resistant starch doesn’t dissolve in water, so as it chugs through your GI tract, it bulks up your poop to push things along, aiding with regularity. But once it gets to your colon, it’s really “where the magic happens,” de Juan says.

There, it acts like a type of soluble fiber called a prebiotic, “serving as the foundation or the soil for the garden of healthy bacteria that is growing there,” she says. Those good gut bugs, or probiotics, eat up that resistant starch as fuel, which allows them to proliferate and fight off the bad guys. As they ferment that starchy goodness, they also create beneficial byproducts, like short-chain fatty acids (SCFAs), Sandra Arévalo, MPH, RDN, a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics, tells SELF. These chemicals provide energy to your colon cells, which helps maintain the integrity of your gut lining (so harmful pathogens are less likely to seep through and make you sick). SCFAs can also lend a hand to your immune system, cutting down on inflammatory substances in your gut while ramping up the release of anti-inflammatory ones.

At the same time, resistant starch, like fiber, may also help keep your blood sugar from spiking and then dropping—which could be something that makes you tired, hungry, or headachey when eating other starches or sugars. (Though, you should know, these fluctuations don’t threaten your health, unless you have diabetes or another condition affecting your blood-sugar control, de Juan says.) The reason resistant starch can keep things more level is because it, again, escapes digestion in your small intestine—your body can’t easily split it up into its constituent sugars and send them into your blood. So less of it hits your bloodstream and at a slower rate, which gives it a lower glycemic index, de Juan explains. That’s why resistant starch can be a nice way for folks with diabetes or prediabetes to incorporate carbs (and get all the vitamins and minerals they can offer) without having to be as concerned about the blood-sugar effects, Julia Zumpano, RD, LD, a registered dietitian with the Center for Human Nutrition at the Cleveland Clinic, tells SELF.

The glacial pace at which resistant starch chugs through your system can also “make you feel a bit fuller, both more quickly and for longer,” Zumpano says. After all, a tempered release of sugar into your blood reduces the need for a big spike of insulin—the hormone that regulates your blood-sugar levels and can also trigger hunger. Not to mention, eating resistant starch might bump up the release of other hormones that signal satiety, “which can help you feel more content with your food intake,” de Juan says. (Whether these appetite-related effects generally spur weight loss, however, is not clear, and it’s important to remember that the relationship between weight and health is far from linear.)

Ultimately, you can think of resistant starch as delivering on the fiber playbook, and in turn, as a helpful assist for hitting the USDA benchmark of 28 grams of fiber per day—which, BTW, most of us fall woefully short of. Though there aren’t specific guidelines for resistant starch, research points to 15 to 2src grams daily as the amount necessary to snag the above benefits over time. But aiming simply to get a source at most meals can help you get there.

How can you work more resistant starch into your diet?

You can ramp up your intake of foods that naturally contain the tough-to-digest starch, prepare typical starches in ways that make them resistant, or, better yet, do both.

The list of foods that inherently contain resistant starch and actually hold onto some of it when cooked is pretty small—basically, whole grains like oats and barley and legumes like lentils, peas, and beans. For the former, you can eat them freshly cooked, but chilled preparations will ensure you’re getting the max resistant-starch goodness. Both de Juan and Zumpano recommend overnight oats—soaking raw oats in milk or a milk alternative for several hours to make them tasty and soft (without knocking out a chunk of their resistant starch with a heat treatment). In the case of barley, cooking and then cooling it (for instance, to serve in a cold grain salad) will do the trick.

With the legumes, you have more flexibility since a greater portion of their resistant starch holds up even amid heat—so feel free to cook away. But if you do cook and then, yep, cool them first before chowing down, you’ll preserve even more of their OG resistant starch. Think: cold bean medley (canned ones work here!), or peas or lentils sprinkled atop a salad. Arévalo also recommends blending chilled or canned beans with herbs or spices to make a dip.

A different type of resistant starch is also found naturally in raw potatoes…but it disintegrates when you cook them. As with the above, you can restore some of it by refrigerating cooked potatoes and eating them chilled (as in a potato salad), or reheating them from that cooled state, de Juan points out. Unripe bananas and plantains also fall into this bucket, but as they ripen, they will naturally turn into a regular starch, de Juan says. It’s the reason Zumpano always buys hers on the greener side and aims to eat them while they’re still in that state.

Finally, there are foods that don’t boast much resistant starch as is—but wind up developing a good amount of it through cooking and then cooling them completely (ideally for at least 24 hours in the fridge or freezer), due to the aforementioned process of retrogradation. That would be things like pasta salad, reheated rice or pasta from the fridge, or toast made from previously frozen bread—and yes, even the white types count. (Just be sure that when you go to refrigerate the cooked items, particularly rice, you do so within two hours of cooking to lower your chances of bacterial contamination, de Juan adds.)

Whether you’re munching on oats or green bananas, or embracing the chilled next-day carbs, just note that ramping up resistant starch also comes with the same caveat as eating more of any kind of fiber: It might cause some bloating and gas, at least at first. That’s just a side effect of all that good fermentation going on among your gut bugs. Arévalo suggests gradually upping your intake (starting with, say, one serving of lentils or pasta salad every other day) and drinking plenty of water to keep things flowing smoothly as you do so.

Related:

• 11 Foods That Probably Aren’t as High in Fiber as You Think
• 6 Ways to Make Creative, Filling Salads That Keep You Satisfied, According to an R.D.
• A GI Doc Shares the Gut-Friendly Breakfast She Eats Every Single Day

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