Resistant starches are starches that the body cannot break down to use for energy. Instead, these starches pass through the digestive system either partially or entirely. Resistant starch is different than fiber, but it acts in a very similar way.

Starch is a type of carbohydrate that comprises a long chain of sugar molecules. The body can usually break down starches very easily and use this sugar for energy. These starches exist in many different plant foods, including potatoes, rice, and corn.

Various types of resistant starch occur in different foods, and adding them to the diet may have some digestion-related health benefits. Keep reading to learn more.

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Legumes, seeds, and many grains are abundant in type 1 resistant starch.

Resistant starch is an umbrella term that includes four or five different types of starch.

The different types of resistant starch vary in either their physical structure or the reasons why they are resistant to digestion.

Many foods will contain more than one type of resistant starch, depending on how a person cooks them or when they choose to eat them.

Type 1

Type 1 resistant starch remains stuck to the fibrous cell walls of the food that the person eats. The person cannot physically digest the fiber or the starch itself. Type 1 resistant starch is abundant in legumes, seeds, and many grains.

Type 2

Type 2 resistant starch is more common in some raw foods and has a specific structure that makes it difficult for people to digest. For instance, a slightly unripe banana would be higher in type 2 resistant starch than a fully ripe banana.

Type 3

Type 3 resistant starch is a highly resistant starch that forms during the process of heating and then cooling starchy foods. For instance, allowing rice or potatoes to cool after cooking them will turn some of the starches into highly resistant starch.

Type 4

Type 4 resistant starches are processed and modified forms of starch. These resistant starches are entirely artificial.

Type 5

Type 5 resistant starch is starch that has bonded with a type of fat, changing its structure and making it more resistant to digestion.

In the body, resistant starch acts very similarly to some types of fiber. These starches pass through the small intestine without undergoing digestion, allowing them to feed the bacteria in the colon.

As digestive bacteria play a crucial role in overall health, it is important to find ways to feed and keep them healthy.

Improved digestive and colon health

When resistant starches arrive in the colon, they feed healthy bacteria, which turn these starches into a few different short-chain fatty acids. These fatty acids include butyrate, which is an important component for the cells of the colon.

Butyrate reduces the levels of inflammation in the colon. In doing this, it can help protect against issues relating to the digestive system, such as ulcerative colitis and inflammatory colorectal cancer.

In theory, butyrate may also help with other inflammatory issues in the bowel, such as:

While these potential benefits are promising, most of the research to date has involved animals rather than humans. High quality human studies are necessary to help support these claims.

Improved insulin sensitivity

Eating resistant starch may help improve insulin sensitivity in some people. This possible benefit is very important because lower insulin sensitivity may play a role in several disorders, including obesity, diabetes, and even heart disease.

One study found that men with overweight or obesity who ate 15–30 grams (g) of resistant starch each day had increased insulin sensitivity compared with men who did not eat these starches.

However, the female participants did not experience these effects. The authors call for more research to determine the reason for this difference.

Feeling more full

Eating more resistant starch may also help people feel full. A 2017 study found that eating 30 g of resistant starch a day for 6 weeks helped decrease hormones that cause hunger in healthy people with overweight. Eating more resistant starch also increased compounds that help a person feel less hungry in the morning.

Including resistant starch in the diet may, therefore, aid weight loss efforts by increasing the amount of time for which a person feels satisfied after a meal. This increased satiety could prevent unnecessary snacking and excessive calorie intake.

Although fiber and resistant starch differ in their molecule structure, the effects that they have on the body are very similar. As a result, many people classify resistant starch as a form of fiber.

Both resistant starch and fiber are types of carbohydrates that the body has trouble breaking down.

In the large intestine, resistant starch acts the same as fiber. It feeds healthy bacteria and promotes the fermentation that creates healthful byproducts, such as butyrate.

Also, like fiber, resistant starch increases stool bulk and can help with bowel movement speed. Due to this, resistant starch might also help alleviate constipation.

Some foods that are high in resistant starch include:

  • toasted Italian bread
  • pumpernickel bread
  • corn flakes
  • puffed wheat cereals
  • oats
  • muesli
  • potato chips
  • raw bananas
  • white beans
  • lentils

Additionally, cooking and then cooling some starchy foods, such as white potatoes and rice, may increase their levels of resistant starch.

Learn about the differences between white rice and brown rice here.

Resistant starch acts similarly to fiber in the body, and it is a part of many everyday foods. As such, there is generally little risk of side effects when eating resistant starch.

However, eating higher levels of resistant starch may cause mild side effects, such as gas and bloating. The digestion of resistant starch may cause less gas than the digestion of some fibers, though.

Some individuals may also have allergies or reactions to specific foods that are high in resistant starch.

Read about the risks of eating too much fiber here.

Resistant starch is an important part of a healthy digestive system, and it may offer several protective effects. However, most of the research surrounding resistant starch is in its early stages.

Eating about 15–30 g of resistant starch each day may help protect the body against inflammation in the digestive system. It may also help keep a person satisfied after meals and increase insulin sensitivity.

Cooking high starch foods, such as pasta, rice, or potato, and then allowing them to cool before eating them is a simple way to get more resistant starch into the diet.