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Evidence Based

Cooling Some Foods After Cooking Increases Their Resistant Starch

Not all carbs are created equal. From sugars to starches to fiber, different carbs have different effects on your health.

Resistant starch is a carb that is also considered a type of fiber (1).

Increasing your intake of resistant starch can be beneficial for the bacteria in your intestines as well as for your cells (2, 3).

Interestingly, research has shown that the way you prepare common foods like potatoes, rice and pasta may change their resistant starch content.

This article will tell you how you can increase the amount of resistant starch in your diet without even changing what you eat.

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What Is Resistant Starch?

Cooked Potatoes With Herbs

Starches are made up of long chains of glucose. Glucose is the main building block of carbs. It is also a major source of energy for the cells in your body.

Starches are common carbs found in grains, potatoes, beans, corn and many other foods. However, not all starches are processed the same way inside the body.

Normal starches are broken down into glucose and absorbed. This is why your blood glucose, or blood sugar, increases after eating.

Resistant starch is resistant to digestion, so it passes through the intestines without being broken down by your body.

Yet it can be broken down and used as fuel by the bacteria in your large intestine.

This also produces short-chain fatty acids, which can benefit the health of your cells.

Top sources of resistant starch include potatoes, green bananas, legumes, cashews and oats. A full list is available here.

Summary: Resistant starch is a special carb that resists digestion by your body. It is considered a type of fiber and can provide health benefits.
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Why Is It Good for You?

Resistant starch provides several important health benefits.

Since it is not digested by the cells of your small intestine, it is available for the bacteria in the large intestine to use.

Resistant starch is a prebiotic, meaning it is a substance that provides “food” for the good bacteria in your intestines (2).

Resistant starch encourages bacteria to make short-chain fatty acids like butyrate. Butyrate is the top energy source for the cells in your large intestine (3, 4).

By aiding in the production of butyrate, resistant starch provides the cells of your large intestine with their preferred source of energy.

Additionally, resistant starch may decrease inflammation and effectively change the metabolism of the bacteria in your intestines (5, 6).

This leads scientists to believe that resistant starch may play a role in preventing colon cancer and inflammatory bowel disease (5, 6).

It can also reduce the rise in blood sugar after a meal and improve insulin sensitivity, or how well the hormone insulin brings blood sugar into your cells (7, 8).

Problems with insulin sensitivity are a major factor in type 2 diabetes. Improving your body’s response to insulin through good nutrition can help fight this disease (9, 10).

Along with potential blood sugar benefits, resistant starch may be able to help you feel fuller and eat less, too.

In one study, researchers tested how much healthy adult men ate at one meal after consuming resistant starch or a placebo. They found that participants consumed about 90 fewer calories after consuming resistant starch (11).

Other research shows that resistant starch increases feelings of fullness in both men and women (12, 13).

Feeling full and satisfied after a meal may help reduce calorie intake without the unpleasant feelings of hunger.

Over time, resistant starch could potentially help you lose weight by increasing fullness and decreasing calorie intake.

Summary: Resistant starch can provide fuel for the good bacteria in your large intestine and may improve insulin resistance. It also promotes feelings of fullness and can lead to decreased food intake.
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Cooling Some Foods After Cooking Increases Resistant Starch

One type of resistant starch is formed when foods are cooled after cooking. This process is called starch retrogradation (14, 15).

It occurs when some starches lose their original structure due to heating or cooking. If these starches are later cooled, a new structure is formed (16).

The new structure is resistant to digestion and leads to health benefits.

What’s more, research has shown that resistant starch remains higher after reheating foods that have previously been cooled (17).

Through these steps, resistant starch may be increased in common foods, such as potatoes, rice and pasta.

Potatoes

Potatoes are a common source of dietary starch in many parts of the world (18).

However, many debate whether potatoes are healthy or not. This may be partially due to potatoes’ high glycemic index, a measure of how much a food raises blood sugar levels (19).

While higher potato consumption has been associated with an increased risk of diabetes, this could be caused by processed forms like french fries rather than baked or boiled potatoes (20).

How potatoes are prepared impacts their effects on health. For example, cooling potatoes after cooking can substantially increase their amount of resistant starch.

One study found that cooling potatoes overnight after cooking tripled their resistant starch content (21).

Additionally, research in 10 healthy adult men showed that the higher amounts of resistant starch in potatoes led to a smaller blood sugar response than carbs with no resistant starch (22).

Rice

It is estimated that rice is a staple food for approximately 3.5 billion people worldwide, or over half of the world’s population (23).

Cooling rice after cooking may promote health by increasing the amount of resistant starch it contains.

One study compared freshly cooked white rice to white rice that was cooked, refrigerated for 24 hours and then reheated. The rice that was cooked then cooled had 2.5 times as much resistant starch as the freshly cooked rice (17).

Researchers also tested what happened when both types of rice were eaten by 15 healthy adults. They found that eating the cooked then cooled rice led to a smaller blood glucose response.

While more research in humans is needed, one study in rats found that eating rice that had been repeatedly heated and cooled led to less weight gain and lower cholesterol (24).

Pasta

Pasta is commonly produced using wheat. It is consumed all over the world (25, 26).

There has been very little research on the effects of cooking and cooling pasta to increase resistant starch. Nevertheless, some research has shown that cooking then cooling wheat can indeed increase resistant starch content.

One study found that resistant starch increased from 41% to 88% when wheat was heated and cooled (27).

However, the type of wheat in this study is more commonly used in bread than pasta, although the two types of wheat are related.

Based on research in other foods and isolated wheat, it is possible that resistant starch is increased by cooking then cooling pasta.

Regardless, more studies are needed to confirm this.

Other Foods

In addition to potatoes, rice and pasta, resistant starch in other foods or ingredients can be increased by cooking and then cooling them.

Some of these foods include barley, peas, lentils and beans (27).

More research is needed to determine the full list of foods in this category.

Summary: The resistant starch in rice and potatoes may be increased by cooling them after cooking. Increasing resistant starch may lead to smaller blood sugar responses after eating.
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How to Increase Your Resistant Starch Intake Without Changing Your Diet

Based on the research, there is a simple way to increase your resistant starch intake without changing your diet.

If you regularly consume potatoes, rice and pasta, you may want to consider cooking them a day or two before you want to eat them.

Cooling these foods in the fridge overnight or for a few days may increase their resistant starch content.

Moreover, based on data from rice, cooked and cooled foods still have higher resistant starch content after reheating (17).

This is a simple way to increase your fiber intake since resistant starch is considered a form of fiber (1).

However, you may feel that these foods taste best freshly cooked. In that case, find a compromise that works for you. You might choose to sometimes cool these foods before eating them, yet other times eat them freshly cooked.

Summary: A simple way to increase the amount of resistant starch in your diet is to cook potatoes, rice or pasta a day or two before you want to eat them.
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The Bottom Line

Resistant starch is a unique carb because it resists digestion and leads to several health benefits.

While some foods have more resistant starch than others to begin with, the way you prepare your food can also impact how much is present.

You may be able to increase the resistant starch in potatoes, rice and pasta by cooling these foods after cooking and reheating them later.

Although increasing resistant starch in your diet may have several potential health benefits, there are also other ways to increase your fiber intake.

Deciding whether or not preparing foods this way is worth it may depend on if you regularly consume enough fiber.

If you get plenty of fiber, it may not be worth your trouble. However, if you struggle to eat enough fiber, this may be a method you want to consider.

An evidence-based article from our experts at Authority Nutrition.
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