Understanding Resistant Starch and Its Benefits

A recent review in Frontiers in Nutrition brings attention to resistant starch — the kind found naturally in foods like beans, bananas, and cooled potatoes. This type of carbohydrate might actually enhance blood sugar regulation, lessen inflammation, and assist with weight management.

However, experts warn against viewing day-old rice as a one-size-fits-all solution. Simply integrating resistant starch into a diet heavy in refined carbs and sugars won’t negate existing health issues. Dietitians suggest a broader perspective: focus on creating meals from fiber-rich foods such as legumes, whole grains, and veggies. This approach tends to promote gut health and yields longer-lasting benefits for blood sugar, cholesterol, and overall wellness.

For many years, the narrative around carbohydrates—especially refined ones like those in white bread, pasta, and rice—has often been negative. But perhaps now, a lesser-known carb is gaining recognition.

The aforementioned review indicates that resistant starch may have a positive impact, suggesting it’s worth considering foods that contain it, which you might already have in your kitchen.

Resistant starch naturally occurs in items like beans, bananas, and potatoes. Interestingly, the cooking and cooling process can increase the resistant starch level in certain foods. So, if you think about leftover rice or cold pasta salads, you’re on the right track.

Before rushing to chill every carb in the pantry, though, dietitians point out that the situation is more complex than online discussions often make it seem. “The claimed benefits might be oversold,” notes Desiree Nielsen, a registered dietitian and podcast host.

Additions of resistant starch to a diet saturated with ultra-processed foods won’t necessarily reverse damage caused by excessive sugar or saturated fats. “To genuinely benefit from adding resistant starch, it’s important to make sustainable dietary changes across the board,” Maya Feller, another dietitian, emphasizes. Indigenous communities have practiced these wholesome eating habits for generations.

What is Resistant Starch?

Resistant starch is categorized as a type of carbohydrate that your body struggles to digest. Unlike standard starches that break down into sugar, resistant starch stays intact and reaches the colon. In the colon, it ferments and serves as nourishment for your gut bacteria, leading to unexpected health advantages.

The Five Types of Resistant Starch

Feller outlines five types of resistant starch, each influencing the body differently. The amount of resistant starch can vary significantly based on how food is prepared, which is part of what makes this topic intriguing:

• RS1: Found in whole plant foods like legumes and whole grains; the tough cell walls make them less digestible, which benefits health.
• RS2: Found in raw, unripe starches like green bananas and uncooked potatoes; its crystalline structure resists digestion.
• RS3: Created when starchy foods like rice or potatoes are cooked and cooled; cooking makes the starch digestible, but cooling changes its structure to make it less so.
• RS4: A synthetic form that is chemically modified; think fiber-enhanced snack bars.
• RS5: Formed when starches interact with fats through industrial processes, rendering them indigestible.

Nielsen advises focusing on RS2 and RS3 sources, as they ferment differently in the large intestine, making them more effective prebiotics that enhance gut health.

Potential Health Benefits of Resistant Starch

A long-term study among U.S. adults published in Frontiers of Nutrition in 2022 showed a link between higher resistant starch consumption and a reduced risk of dying from cancer or other causes. It tracked participants for 19 years, revealing promising correlations between resistant starch intake and improved health outcomes. Nevertheless, researchers stress that we need further studies to determine the optimal amount for maximum benefits.

“We’ve shifted from saying ‘We are what we eat’ to ‘We are what we digest and absorb,’” Nielsen explains.

In another study from Frontiers in Nutrition, published in 2024, rats fed mung beans—which are rich in resistant starch—had a staggering 96% decrease in blood sugar levels. Also, a smaller study from 2015 indicated that men classified as overweight benefited from consuming 15 to 30 grams of resistant starch daily, improving insulin sensitivity; though results were less distinct for women, which signals the need for more investigation.

Health Issues Addressed by Resistant Starch

Nielsen references another analysis indicating that 10 to 45 grams of resistant starch daily led to improved insulin sensitivity in overweight individuals. Feller adds that a fiber-rich diet—inclusive of resistant starch—often results in better blood sugar control, lower blood pressure, and a more favorable lipid profile.

If high cholesterol is a concern for you, Feller suggests incorporating a variety of fiber sources, including resistant starch, for improvements in lab results. Many appreciate that as their numbers improve, they also experience better sleep, clearer focus, and sometimes, even weight loss.

Is Resistant Starch Really Better Than Regular Starch?

In a way. But don’t expect miraculous results from a bowl of chilled rice.