You may have seen lately that one way to eat pasta is to cook it, refrigerate it, then eat it cold. It’s not just pasta salad. It’s resistant starch. And the benefits of resistant starch for gut health have been emerging in research for the last couple of years.

Beyond cold pasta, you can get resistant starch from green bananas, cold mashed potatoes and cold rice. But is adding more starch to our diets really a good idea?

What is resistant starch?

Resistant starch is a carbohydrate that ‘resists’ digestion. Most carbs are broken down in the small intestines, producing glucose and fuel for the body, while raising blood glucose in the process. But resistant starch moves right through the small intestines to the large intestines. In the large intestines, resistant starch ferments, producing food for the good bacteria in the gut. In this way, resistant starch acts like a prebiotic fiber, producing healthy short chain fatty acids. These fatty acids promote a healthy gut barrier and have anti-inflammatory effects.

Are there different types of resistant starch?

Yes. Types of resistant starch are classified based on their source or structure – by the way in which they resist our digestive enzymes.

Resistant Starch 1

Physically inaccessible starch, found in seeds, whole grains and legumes, this type of resistant starch (RS) is physically protected from digestion by the outer coating of a grain (the bran), a seed coating or by cell walls of plants. Some examples include:

• Cooked beans and lentils
• Seeds like millet, chia seeds, flaxseeds, pumpkin seeds
• Whole grains like wheat berries, or partially milled whole grains like oats
• Raw oats in overnight oats have more resistant starch than cooked oatmeal
• Muesli (raw oats and seeds like sunflower seeds and flaxseed)

Resistant Starch 2

Native granular starch, this resistant starch is found in green bananas, plantains, high-amylose maize starch and raw potato starch used in baking. This resistant starch stays intact until it reaches the colon (large intestines) because these starch granules are resistant to digestive enzymes. Here are some suggestions on how to eat them along with other resistant starch 2 sources:

• Slice a green banana into oatmeal
• Use arrowroot powder in these bean burgers
• Sprinkle gut-friendly raw potato starch on food as a supplement. It’s not recommended to eat raw potatoes since eating them can cause stomach upset.

Resistant Starch 3

Retrograded starch, found in starchy foods like potatoes, rice, barley and pasta only after they have been cooked and cooled at least 12 hours. It’s this cooling process that forms the resistant starch. During this process, the gelatinized starch molecules realign to become resistant to digestive enzymes.

While it might seem like magic, it’s actually food science. But it’s true that cooking and cooling higher-carb foods like pasta, white rice, potatoes and sweet potatoes can make them healthier, because this process increases the resistant starch content by a modest amount.

Cooking and cooling RS1 sources like quinoa (a seed), whole grains (barley and oats) and legumes like beans and lentils also increases their resistant starch (RS3) content.

The good news is that these cooked and cooled foods do not have to be eaten cold; they can be reheated and still maintain the retrograded starch form.

Resistant Starch 4

Chemically modified starch, found in processed foods, these starches are manufactured to resist digestion. RS4 starches are often added to increase the fiber content in protein bars, cereals, breads, pasta and other packaged foods. Check nutrition labels for these examples:

• Tapioca Fiber: This resistant starch ingredient is found in low-carb bars, cereals or shakes.
• Resistant Wheat Starch: Find this ingredient in keto rolls and breads.

What are the gut health benefits of resistant starch?

Resistant starch acts as a prebiotic that feeds beneficial bacteria in the gut, promoting a healthy gut microbiome, and also reducing the risk of colon cancer, explains Erin Kenney, MS, RD, LDN, HCP, CPT, gut health dietitian at Nutrition Rewired.

“These prebiotics feed your gut flora and support production of short chain fatty acids which can help with leaky gut syndrome and reduce inflammation,” says Kenney. “Green bananas and many other resistant starches are also FODMAP-friendly.”

Are there other benefits of resistant starch?

The research on the benefits of resistant starch is emerging. Research has been done in animals and limited studies in humans.

“There are a variety of benefits of resistant starch,” says Kenney. “Resistant starch has been shown to lower blood sugar levels by reducing the rate of glucose absorption.” Blood glucose and insulin levels are lower because these starches are not absorbed in the small intestine, explains Kenney.

Increased satiety is another benefit. Kenney explains that resistant starch is more filling than other types, which can lead to reduced food intake and weight loss. “The starch in unripe bananas and other resistant starches can make you feel full faster during a meal and keep you full longer.”

Resistant starch has also been shown to lower LDL (bad) cholesterol levels which can reduce the risk of heart disease.

“These prebiotics enhance the gut microbiota which can make the gut more efficient at absorbing nutrients. Studies have shown increased calcium absorption with the consumption of resistant starch,” says Kenney. Improved calcium and mineral absorption can mean better bone health. This may also help minimize bone loss during weight loss.

Is adding more starch to your diet really a good idea?

Resistant starch is a type of fiber. Americans are not getting enough fiber.

“Think of resistant starch as fiber, somewhere in between soluble fiber and insoluble fiber,” says Kristin Neusel, MS, RD, LD, CDCES, NASM-CPT, Registered Dietitian and Certified Diabetes Care & Education Specialist.

“It has some of the same potential benefits as both soluble and insoluble fiber including better colon health and decreased cholesterol. But researchers have also found that resistant starch can help lower fasting blood glucose and improve insulin sensitivity which has important implications for people with diabetes, and also those of us who want a slow steady rise and fall of our blood sugar throughout the day,” says Neusel. “Controlling blood sugar can reduce inflammation throughout the body, and can decrease the risk of chronic disease.”

Neusel recommends layering resistant starch with other fibers for synergistic metabolic benefits, and for improved gut health. “Since resistant starches are found along with other types of fiber in a variety of foods, eat different types of beans, fruits, vegetables and whole grains daily. Nowadays it’s easy to get resistant starch through different breads and baked goods that use resistant starch as their main ingredient.”

Neusel reminds people that it’s a good idea to increase fiber consumption slowly, while also drinking plenty of water to avoid gastrointestinal discomfort.

What are dietitians’ favorite ways to eat resistant starch?

“I slice up green bananas and air-fry them into chips. Green plantains work great like this too,” says Neusel.

“I use organic green banana flour in baked goods. It’s a great way to get it in if you don’t like green bananas,” says Kenney.

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