Pasta and rice can be healthier as leftovers Here’s why.

It sounds like yet another internet health hack: cook some pasta or white rice and let it cool in the refrigerator overnight. By the next day, some of the natural starches in the food will have been converted into healthier versions, called resistant starches, which have been linked to a range of health benefits including lower blood sugar levels, better gut health and a reduced risk of certain types of cancer.

The idea that you can change the health properties of a food just by cooking and cooling it may sound too good to be true. But according to experts like Balazs Bajka, an intestinal physiologist at King’s College London, something is going on.

Refrigerating starchy foods can cause some changes in their structure that can benefit your health, said Dr. Bajka. Here’s what we know.

What is resistant starch?

Resistant starch is a type of fiber found naturally in many types of plant foods, such as whole grains, beans, nuts, seeds, green bananas and plantains. But it is also possible are increased in other foods which contain mainly plain starches, such as rice, pasta and potatoes, after they have been cooked and then cooled.

Cooking and cooling causes the food’s starch molecules to become tightly packed together, making them harder to digest, said Dr. Bajka. When this happens, the starch becomes “resistant,” meaning the sugar molecules are not broken down and absorbed into your bloodstream as easily as they normally would.

What are the health benefits of resistant starch?

Because resistant starches are not easily digested, they do not cause spikes blood sugar as much as regular starch, says Kimberley Rose-Francis, a dietitian in Florida who specializes in working with patients with diabetes.

Instead, the resistant starch passes into your intestines, where it can feed the good microbes in your gut, said Dr. Bajka. This helps them to flourish and create useful molecules which have been linked to lower cholesterol and inflammation and better gut health in general.

There is also some evidence that resistant starch may play a role in reducing the risk of certain types of cancer, says Annette M. Goldberg, a dietitian at the Dana-Farber Cancer Institute in Boston, although more research is needed.

In one recent trial of more than 900 people with Lynch syndrome, a genetic condition that increases the risk of developing several types of cancer, researchers divided participants into two groups: one who took 30 grams of resistant starch supplement every day for up to four years, and another who took a placebo.

Up to 20 years later, researchers found that although there was no change in participants’ risk of colorectal cancer, those who took the resistant starch supplements were half as likely as those who took the placebo to develop other cancers, especially those of the upper gastrointestinal tract, such as in the stomach or pancreas. (The supplements used in the trial were supplied by a company that makes starch ingredients, but the company was not involved in the design or analysis of the study.)

When you cook and cool starchy foods, you also effectively increase fiber content, says Mindy Patterson, associate professor of nutrition and food sciences at Texas Woman’s University.

Fiber has been linked to a variety of health benefits, including a reduced risk of heart disease, type 2 diabetes and some types of cancer. And when consumed as resistant starch, it appears less likely than other forms of fiber to cause unpleasant effects such as gas or bloating, said Dr. Patterson.

it comes down to

Most people will benefit from consuming more fiber, whether it’s in the form of resistant starch or not, said Dr. Patterson.

Good sources of fiber include whole grains, fruits, vegetables and legumes. And aside from eating foods that naturally contain resistant starch, such as beans, barley, green bananas, and oats, you can increase the levels of resistant starch in foods like pasta, potatoes, and rice by cooking and cooling them. , said Dr. Patterson.

This technique can be especially helpful for people with type 2 diabetes or pre-diabetes, she said.

Ms. Rose-Francis encourages many of her clients with diabetes to experiment with cooking and cooling methods with rice, pasta or potatoes to see if that makes a difference in their blood sugar levels.

This can be a powerful technique for them, she said, because many people with diabetes avoid eating starchy foods for fear that their blood sugar levels would become too high. This could explain why one of her TikTok videos on the topic has been viewed 1.3 million times. “It gives people hope,” she says.