You’ve probably heard of the importance of insoluble and soluble fiber and prebiotics (another type of fiber) for gut health. But these fiber varieties have a less well-known cousin: resistant starch. “I hear a lot from clients about prebiotics, but resistant starch never comes up in my practice. Most people haven’t heard of it,” says Moskovitz. Yet despite its under-the-radar vibe, it plays an important role in our digestive health.
What is resistant starch, and why is it good for me?
Resistant starch is both a starch and a type of fiber. Let us explain.
Carbohydrates consist of fiber, sugar, and/or starch. Your body uses both starch and sugar as its main source of fuel. Fiber is unique because it isn’t broken down into glucose (aka sugar), giving it special health-boosting properties. Resistant starch passes through the small intestine intact and is fermented in the large intestine, producing short chain fatty acids that, similarly to probiotics, feed healthy bacteria to support a balanced microbiome, notes Moskovitz.
Meanwhile, insoluble fiber (which can't be digested) is a power wash for your GI tract that helps to keep your BMs regular. Soluble fiber soaks up and eliminates substances in your gut that your body doesn’t need. Together, these three types of fiber work together to slow down the digestion of other foods and the absorption of glucose into the bloodstream, all while supporting the health of your gut microbiome.
Getting more fiber in your diet has been linked to a reduced risk of type 2 diabetes, cardiovascular disease, and colorectal cancer. Resistant starch, specifically, may promote:
1. Better gut health
Similar to other fiber, resistant starch adds bulk to your stools and improves gut motility, which helps to lower your cholesterol. Resistant starch also acts like prebiotic after it’s transformed into short-chain fatty acids in the intestine, feeding healthy gut bacteria that decrease the risk of developing colon cancer. “The link between increased resistant starch intake and colon cancer prevention is well-researched,” says New York City-based dietitian Brigitte Zeitlin, RD.
2. Improved glucose sensitivity
In order to use glucose for energy, our bodies release insulin. The more sensitive we are to insulin (meaning it only takes a bit of insulin to do its job), the better our bodies can control our blood sugar levels—and the less likely we are to develop conditions linked to insulin resistance, including diabetes, obesity, and heart disease, says Zeitlin. Like all fiber, resistant starch has been linked by several studies to improved insulin sensitivity.
3. Healthy Weight management
The fuller you feel, the less likely you are to over-snack. And foods high in fiber, including resistant fiber, help us to feel more satisfied every time we eat. Indeed, legumes and whole grains—both of which are good sources of resistant starch—have been shown to be help promote weight loss and healthy weight maintenance, says Zeitlin.
Want more intel on gut health? Check out the 411 with You Versus Food host Tracy Lockwood Beckerman, RD:
How much resistant starch should I get every day?
Zeitlin suggests aiming for 15 to 20 grams of resistant starch per day, although there is no standard recommendation that’s universally recognized by health experts. With that said, a 2008 study found that Americans eat only about five grams of resistant starch per day—so we likely could all stand to get more in our diets.
Since many fiber-rich foods, like oats, have all three types of fiber, you’ll naturally hit your resistant starch goals by aiming for 25 to 30 grams of fiber total every day from whole food sources. “You don’t need to worry [specifically] about how much resistant starch, because high-fiber foods contain a mix of all three. In a balanced diet, you’ll get resistant fiber naturally,” says Moskovitz.
What are the best sources of resistant starch in foods?
Want to hedge your bets? The best sources of resistant starch include:
- One cup of white beans: 7.4 g
- A half cup of lentils: 3.4 g
- One medium unripe (green) banana: 4.7 g
- One quarter cup of uncooked rolled oats: 4.4 g (1 cup of cooked oats has 0.5 g)
- One ounce of whole wheat bread: 0.3 g
- One ounce of pumpernickel bread: 1.3 g
- One tbsp of hi-maize resistant starch: 4.5g
The amount of resistant fiber in some foods vary depending on ripeness or whether the food has been cooked. Bananas for example, contain more resistant fiber when they’re green; as they ripen, resistant starch transforms into just straight starch (i.e., sugar). Raw potatoes and uncooked oats contain high levels of resistant starch that turns into active starch once they’re cooked. “But if you eat them cooled, it starts to move back to resistant starch,” says Moskovitz.
Zeitlin recommends focusing on beans and lentils for the biggest nutrition bang per calorie. Try adding white beans (navy beans, cannellini beans, baby lima beans, great northern beans) into your soups, stews, and stir-fries. Or add a scoop of lentils to your salads or soups.
Can you get enough resistant fiber on a low-carb diet?
If you’re super low-carb, getting enough resistant starch and other fiber is tricky, says Zeitlin, since it limits the fiber and resistant starch in your diet. “This usually results in increased feeling of bloat, constipation, and gas in the short term, as a result of your GI tract not getting enough fiber or resistant starch’s healthy bacteria,” says Zeitlin. “In the long term, you could be increasing your risk of inflammation, colon cancer, and other types of chronic digestive illnesses that fiber helps to prevent.” If you’re really set on a low-carb diet or your doctor has recommended sticking to one, you can add a hi-maize resistant starch supplement to foods like soups and smoothies.
Even if you aren’t limiting carbs, you could risk a deficiency in resistant starch and other fibers if you aren’t eating enough whole grains, oats, brown rice, and legumes, notes Moskovitz. Ultimately, the best way to get enough resistant starch: Eat a balanced diet with plenty of whole, plant-based foods, she adds.
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