What You Need to Know About Resistant Starches and the Best 10 Foods That Have Them

Resistant starch is a type of starch that your intestines can't digest. The best foods that have resistant starch are oats, millets, beans, and other foods.

Carbohydrates like potatoes, bananas, and grains all contain resistant starch. This is a type of starch that your intestines can't digest.  

Here’s everything you need to know about the best foods with resistant starch, their health benefits, and how to add them to your diet. 

Resistant starch is a carbohydrate that is similar to dietary fiber and resists digestion. It ferments in the large intestine and acts as a prebiotic. Prebiotics are foods that promote the growth of good bacteria in your gut and boost your immune health. 

There are five different types of resistant starch, and a particular food can have more than one type.

Resistant starch has the following types:

RS1. You can find RS1 in grains, beans, or seeds. It has a large network (matrix) of proteins, which prevents the starch from getting digested.

RS2. RS2 is another naturally resistant starch. You can get it from raw potatoes and unripe or green bananas. 

RS3. RS3 is a retrograded starch, which changes in form after heating and cooling. It forms when starchy foods like potatoes, rice, or pasta are cooked and cooled.

RS4. RS4 is a starchy food that is chemically modified to make it resistant to digestion. 

RS5. RS5 is a new type of resistant starch produced by heating and cooling starchy foods with lipids like fats or waxes. When starch combines with lipids, it develops molecules with long chains of carbon. These prevent the starch from being digested.

Resistant starch has fiber-like properties. It slowly ferments in the large intestines and acts as food for healthy bacteria in your gut. These bacteria improve your digestion and promote well-being. 

Like fiber, resistant starch keeps you full for longer, reducing hunger and helping with weight management. It also helps treat and prevent constipation and gas. It improves nutrient absorption and gut health. It also decreases your risk of developing colon cancer and gallbladder stones.

When starch gets digested, it breaks down into glucose, which enters your bloodstream. Since resistant starch isn’t digested in the intestine, it doesn’t increase blood glucose. Consequently, it can help manage type 2 diabetes and control your blood sugar levels. 

Research also shows that resistant starch can help prevent chronic problems like inflammatory bowel disease, high cholesterol, and heart disease.

Foods with resistant starch include the following:

1. Oats

Cereals like oats are rich in RS1 and RS3 starch. Oats will help you decrease your blood sugar by increasing sugar uptake in your body. They also prevent inflammation and boost gut bacteria.

2. Millets

Millets are whole grains that are a sustainable source of resistant starch. Manufacturers process millets or millet flour using heat or chemical processes to increase their resistant starch levels. Chemical treatments increase the protein and fats in millets, making the network of proteins strong enough to resist digestion.

A 100-gram portion of starch from foxtail millet contains 17 grams of resistant starch.

3. Beans

Legumes like beans are rich in resistant starch. A study showed that cooked pinto beans in particular are a great source of resistant starch. After cooking them for an hour, they have higher levels of resistant starch than black beans.

Meanwhile, 100-gram portions of starch from dried kidney beans and soybean are about 32% and 11% resistant, respectively.

4. Chickpeas

Chickpeas have less resistant starch when they’re raw, but as their cooking time increases, their resistant starch levels rise. After an hour of cooking, 100 grams of chickpeas contain 2.6 to 5 grams of resistant starch.

5. Potatoes

Raw potatoes naturally contain high levels of RS2 starch, and these levels can increase further after cooking. Additionally, a study revealed that baked potatoes have higher resistant starch content than boiled potatoes. Also, cooled potatoes have more resistant starch than hot or reheated potatoes.

A fresh, raw potato has 72 grams of resistant starch, while potato starch or flour contains about 79 grams per 100 grams of starch.

6. Green banana 

Like potatoes, green bananas are naturally rich in resistant starch. About 50% of unripe or green banana pulp is RS2 starch. A study in rats showed that these high resistant starch levels in green bananas can help with weight control and obesity.

Of the total starch in green bananas, about 38% is resistant starch. In contrast, ripe bananas have less than 5% resistant starch.

7. Rice

Research shows that 20.8% of the starch in glutinous/sushi rice is resistant starch. Other types of rice have lower levels of resistant starch, though. 

One study showed that cooked rice had less than 3% resistant starch. Other research suggests that cooked and cooled rice has more resistant starch, though, than rice that is cooked but not cooled. 

For elevated resistant starch content, rice can be processed with fats to form RS5 starch. The fats will bind to the starch in rice and prevent its digestion for several hours. Rice with higher levels of RS5 resistant starch can be a good food choice if you have diabetes and weight problems.

Even today, researchers are continuing to breed different varieties of rice with improved resistant starch contents.

8. Quinoa 

Quinoa contains RS4 starch, which can be modified using citric acid through the acid esterification process. The citric acid binds to the starch and makes it difficult to digest. A study revealed a two-fold improvement in resistant starch content after citric acid was added to quinoa. Its resistant starch content increased to 1.10 grams per 100 grams of starch.

9. Cassava

Cassava products like starch, tapioca, and sago are rich in resistant starch, with levels ranging from 0.56% to 1.1%. A study showed that 100 grams of starch extracted from cassava contained 80.8 grams of resistant starch. Having cassava and its products, then, can likely improve your gut health.

10. Buckwheat

Hulled buckwheat seeds/groats contain high resistant starch content. Research also suggests that cooked buckwheat groats contain more resistant starch than cereal grains like rice. Buckwheat groats contain 23.6 grams of resistant starch in 100 grams of starch, making them healthy for your gut.

Add the mentioned foods to your diet for resistant starch. Cook rice, potatoes, and pastas, then cool them overnight. Add beans to your salads, soups, or stews. Incorporate oats into your diet by soaking them in dairy milk or plant-based milk. Use green bananas or cassava flour instead of other types of flour. Keep in mind, though, that cooking and baking can affect the resistant starch content in the flour.