Resistant Starch: How to Optimize Your Gut Health

Resistant Starch: How to Optimize Your Gut Health

Thirty years ago, starchy foods such as white bread, rice, cakes, and noodles, at breakfast, lunch, and dinner were the staple food.

But now, they tend to have a bad reputation in the world of dieting.

However, some varieties of these foods contain resistant starch, a fiber-like carbohydrate that has many potential health benefits.

Keep reading to learn more about resistant starch, how it can benefit your gut health, and some safety points to remember.

What Is Resistant Starch?

Starch is a type of carbohydrate in the diet, and most dietary supplements, such as white bread, cakes, and noodles, consist of a large percentage of highly digestible starch.

So, when the body digests starchy foods, it typically breaks them down into glucose (sugar) in the small intestine.

However, starches resistant to digestive enzymes have been termed resistant starch.

The American Association of Cereal Chemists defined resistant starch as "the edible part of plant foods or analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation."

This means though resistant starch is a type of carbohydrate, it does not break down into glucose in the small intestines. Instead, they pass to the colon (large intestine) to be fermented by microbiota.

As mentioned before, 30 years ago, starchy foods at breakfast, lunch, and dinner were the staple food; however, nowadays, starchy foods are thought to be fattening, which caused people to follow a low-carb diet for successful weight loss.

But, the fun fact is, as starches are polymers of glucose, they form an important nutritional energy source in the human diet.

Hence starchy foods are a good source of energy and the main source of a range of nutrients in the diet.

Furthermore, resistant starch reduces the caloric density of food due to its indigestibility.

Resistant Starch Types

There are currently five types of resistant starch, and research has been conducted on each type of resistant starch.

Resistant Starch Type-I

Resistant starch type-I is synthesized in the endosperm (the part of a seed that acts as a food store containing starch with protein and other nutrients) of cereal grains or seeds, starch granules, and legumes. They are surrounded by protein matrix and cell wall material. These fibrous cell walls resist digestion.

When cooked as whole kernels or coarsely ground seeds, the thick cell wall of legume seeds in cereal grains prevents water penetration into the starch. Therefore, the starch does not have adequate moisture to gelatinize and swell, due to which the starch is not readily digestible.

Resistant Starch Type-II

Resistant starch type II is found in some starchy foods that display the B- or C-type polymorph, including raw potatoes and green (unripe) bananas. The presence of polymorphs causes them to resist digestive enzymes.

However, after cooking, most of the starch in the food, such as in baked potato and cooked banana, becomes highly digestible due to starch gelatinization and loss of the B- and C-type crystallites.

Resistant Starch Type-III

Resistant starch type III is known as retrograded (reverse) amylose. It is formed when certain starchy foods, including potatoes and rice, are cooked and cooled.

When the food is cooked, the scratch gelatinizes; however, the gelatinized starch realigns itself as the cooked starch cools down. Since amylose has a linear structure, it tends to form double helices, particularly near refrigeration temperatures of 4–5°C. And the double helices of starch molecules are not digestible.

Resistant Starch Type-IV

Resistant starch type-IV is chemically modified starch. The resistant starch type-IV is formed either by cross-linking or by adding chemical derivatives.

A high level of cross-linking loses the ability to swell during cooking and hence isn't digestible. Similarly, a chemical derivative changes the structure of the starch and partially restricts digestive enzymes.

Resistant Starch Type-V

Resistant Starch Type-V is a new category. Type-V-resistant starch is considered thermally stable. The formation of resistant starch is a process that involves an instant reaction after cooking and cooling starchy foods with specific lipids.

How Resistant Starch Can Benefit Gut Health

Resistant starch can proffer several benefits to gut health. Some of these are mentioned in the following.

Decreases Constipation

Constipation is a disorder that affects about 10–20% of the population of Europe. Resistant starch is found to be beneficial for bowel health, which includes loosening constipation. According to a study, green (unripe) bananas, which contain resistant starch type II, can aid constipation.

Encourages Weight Loss

Resistant starch reduces the caloric density of food due to its indigestibility. It increases protein retention during overfeeding, indicating that resistant starch could positively affect body composition. In addition, resistant starch has effects, such as increased fat oxidation and reduced fat storage in adipocytes, that imply that it would be useful for weight loss.

Combats Obesity

The global obesity epidemic has focused researchers on finding novel ways to prevent weight gain or reduce body weight. Obesity is associated with chronic health issues like diabetes, cardiovascular disease, and cancer, among the greatest causes of death in the Western world.

And weight loss can lessen the impact of these health issues. As mentioned before, resistant starch reduces the caloric density of food due to its indigestibility. It has effects, such as increased fat oxidation and reduced fat storage, which can help combat obesity.

Promotes Gastrointestinal Health

The gut microbiota includes a mix of both "good" and "bad" living bacteria. Resistant starch promotes gut health by feeding the 'good bacteria, which are sometimes called the microbiome.

When good bacteria ferment resistant starch, they make short-chain fatty acids, producing beneficial butyrate microbes. The butyrate supplies energy to the cells lining the large intestine, promoting their well-being.

Boosts Overall Gut Health

Summing up all the points above, consuming resistant starch improves gut health. Many studies demonstrated the health benefits of resistant starch, including increased fermentation leading to improved gut health and insulin sensitivity. Resistant starch also reduces caloric density which in turn can reduce obesity.

Other Potential Health Benefits of Resistant Starch

Besides improving gut health, resistant starch also provides other potential health benefits, such as lowering the risk of metabolic syndromes and others.

Lowers Cholesterol

As mentioned before, resistant starch promotes gut health by feeding the 'good bacteria and reducing food's caloric density due to its indigestibility. This can increase fat oxidation and reduce fat storage, which can help combat obesity, which is associated with chronic health issues like diabetes, cardiovascular disease, and cancer. Furthermore, the 2018 meta-analysis indicates that resistant starch also has a cholesterol-lowering effect.

Controls Blood Sugar Level

The body digests starchy foods by breaking them down into glucose (sugar) in the small intestine. However, resistant starch, which is immune to digestive enzymes, passes to the large intestine and is fermented by microbiota. Hence, the food's glucose isn't rapidly released into the bloodstream, and the blood sugar isn't spiked.

Lowers the Blood Pressure

The relationship between diet, gut bacteria, and the availability of short-chain fatty acids(SCFAs) is believed to be the key to the ability of a high prebiotic fiber diet to reduce inflammatory diseases. And as mentioned before, good bacteria ferment resistant starch; they make short-chain fatty acids, producing beneficial butyrate microbes.

And studies have found that a diet high in resistant starch or direct supplementation with acetate, propionate, and butyrate can prevent the development of high blood pressure. And though the evidence is lacking, a combined study proposed that using prebiotic-resistant starches and postbiotics, SCFAs, may lower blood pressure.

Lowers the Risk for Certain Health Conditions

As mentioned before, the gut is home to bacterial cells, both "good" and "bad." And an imbalance in the bacterial cell can risk certain health conditions, such as diabetes, obesity, inflammatory bowel diseases, and colorectal cancer. However, carbohydrates, including resistant starch found to have the potential to correct or prevent a variety of diseases, including obesity, diabetes, inflammatory bowel diseases, and cancer.

Balances Immune System

Although further study is required, a 2020 scientific report offers potential benefits of the resistant starch. Resistant starch has anti-inflammatory molecules which prevent inflammation and can impact the other compartment, whether on microbial composition or metabolite-mediated action.

Furthermore, studies have shown that gut immunity could be transmitted to distal organs through the transit of microbes or metabolites like Short-Chain Fatty Acids (SCFA). SCFA produces bacterial dietary fermentation, especially in the case of a high-resistant starch diet.

The fermentation of resistant starch plays a role in the gut by producing beneficial microbes that signal molecules on resident antigen-presenting cells to cause inflammatory and allergic responses.

Lowers the Risk of Cancer

Cancer is a disease in which certain the body's cells grow uncontrollably and spread to other parts of the body. Treatment for this disease includes chemotherapy, radiation therapy, immunotherapy, and targeted therapy.

However, a trial in almost 1,000 people with a high hereditary risk of a wide range of cancers has shown a major preventive effect from resistant starch. Professor of Human Nutrition at Newcastle University, John Mathers, explains, "We found that resistant starch reduces a range of cancers by over 60%".

Although it needs further research, according to scientists, resistant starch may reduce cancer development by changing the bacterial metabolism of bile acids. It can reduce those bile acids that can damage our DNA and eventually cause cancer.

6 Food That Contains Resistant Starch

Most carbohydrate dietary supplements, such as white bread, cakes, and noodles, consist of starch. However, only a few dietary supplements contain high amounts of resistant starch. Following are some foods that contain high amounts of resistant starch.

1.    Oats

Oats are grown primarily for their edible starchy grains and are among the healthiest grains on earth. The grains are high in carbohydrates like amylose; a type-III resistant starch formed when starchy foods are cooked and then cooled down. Oats also contain about 13 percent protein and 7.5 percent fat and are a good source of calcium, iron, vitamin B1, and niacin.

2.    Rice

Rice is another starchy grain produced roughly by one-half of the world's population, including all of East and Southeast Asia, which are wholly dependent upon rice as a staple food. Furthermore, 95 percent of the world's rice crop is eaten by humans.

A cup of white rice contains 45g carbs, 4.3g protein, 205 calories, 0.4g fat, 0.6g fiber, and 0.1g sugar. And according to a study, cooling the cooked white rice increases resistant starch content. Furthermore, when cooked white rice is cooled for 24 hours at 4°C then reheated, it lowers glucose response compared with freshly cooked white rice.

3.    Beans and Legumes

Legumes often fall far below popular grains. However, the February 2001 issue of the Journal of Nutrition reports that legumes contain substantially higher percentages of resistant starch than cereal grains, flours, and grain-based food products.

George C. Fahey Jr. said, "legumes have a great amount of dietary fiber and the resistant starch; moreover, with their protein, fiber, and resistant starch, these foodstuffs offer good nutrition." For instance, black beans contain the highest amount of total dietary fiber, and 63 percent of their total starch content is resistant starch.

4.    Potato Starch

Potato starch grains are very fine in pure form, and because of this, the potato starch powder is clear white. Potato powder contains resistant starch, increasing intestinal concentrations of short-chain fatty acids (SCFA). And as mentioned before, short-chain fatty acids can help lower blood pressure, balance the immune system, control blood sugar levels, and benefit overall gut health.

5.    Potatoes

Among commonly consumed foods, potatoes are a good source of resistant starch. Resistant starch content in food varies by cooking method and temperature but is constant among commonly consumed varieties of potatoes.

For example, baked potatoes had higher resistant starch contents than boiled, and chilled potatoes had more resistant starch than either hot or reheated potatoes. Furthermore, higher content of resistant starch in raw potatoes has been shown to increase digestion time, potentially providing similar benefits as fermentable fibers.

6.    Green Bananas

Green (unripe) bananas are another great source of resistant starch. The banana-resistant starch belongs to the resistant starch type II and is the main ingredient of green (unripe) bananas. Resistant starch comprises approximately 50% of unripe banana pulp.

And according to a study, banana-resistant starch had a good effect on weight loss and improved the condition of the obese. Consequently reducing health issues like diabetes, cardiovascular disease, and cancer. However, the microstructures of resistant starch from different food sources are not the same. Therefore, the health benefits of banana-resistant starch could not be predicted without testing.

For example, the structures and physicochemical properties of banana-resistant starch differ from variety to variety, and it is found that some banana cultivars do not have good effects on weight loss.

How to Add Resistant Starch to Your Diet?

Adding resistant starch to the diet is easy, especially considering foods that contain high amounts of resistant starch. However, try to incorporate resistant starch slowly and gradually into the diet.

Here's how to incorporate resistant starch:

  • Oats porridge, often recognized as oatmeal, is commonly consumed as breakfast by boiling oats in milk or water.
  • Rice is commonly consumed after boiling it in water or can be ground into flour. Rice is also used in many soups, side dishes, and main dishes in Asian, Middle Eastern, and many other cuisines.
  • Beans can easily be added to salads, pasta, or tacos (if preferred). They can also be baked, added to soups, or made into a bean spread. They are also enjoyed with rice.

Similarly, there are many recipes and ways to add resistant starch to your diet. For example, potatoes alone comprise many dishes like mashed potatoes, potato pasta, or simple baked potato side dishes. However, remember resistant starch content in food varies by cooking method and temperature. Therefore, choose the recipes accordingly and serve cold.

How Much Resistant Starch Should You Take?

Resistant starch is starch that escapes digestion in the small intestine and is later fermented in the large intestine. And according to the 2008 Journal of the American Dietetic Association, three estimates of resistant starch intake were made for each person based on the minimum, mean, and maximum concentration of resistant starch in the food.

And the estimated intake of resistant starch by Americans is approximately 3 to 8 g per person per day. Since too much consumption of anything may lead to certain risks and side effects.

Risks and Side Effects

Although resistant starch has several potential benefits, it also has the potential to cause or perpetuate digestive problems. When or if excessive fermentation occurs in the wrong place (mainly the small intestine due to excessive consumption of resistant starch), it can cause related digestive illnesses such as GERD, IBS, and Celiac disease, to name a few, especially for people with Small Intestinal Bacterial Overgrowth (SIBO).

Final Words

Starch is a type of carbohydrate, and resistant starch is a carbohydrate that is immune to digestive enzymes. Instead, resistant starch escapes digestion in the small intestine and is later fermented in the large intestine.

And though it has several benefits, such as lowering the risk of metabolic syndromes, improving overall gut health, and other potential benefits, it also has the potential to cause digestive problems. Therefore, consume the recommended amount, which is 3g to 8g per person per day.

Also, remember resistant starch content in food varies by cooking method and temperature. With that being said, what's your way of incorporating resistant starch into the diet? Share your preferred recipe.

Back to blog