How Does Resistant Starch Work?
Resistant starch is a form of starch that is not completely broken down by the intestines.
Instead of being absorbed, bacteria in the intestine turn resistant starch into short-chain fatty acids (SCFA).
The small intestine breaks down most starches, a process that converts them into sugar. These types of starches get fully absorbed by the small intestine.
Resistant starch is termed as “resistant” because it is able to resist digestion. During the digestion process, resistant starch travels to the large intestine.
Once in the large intestine, intestinal bacteria begin working to ferment it. In this aspect, resistant starch is similar to fiber.
This fermentation process produces SCFA such as butyrate, propionate and acetate. SCFA are then either absorbed by the body through the colon or used as energy by colonic bacteria.
Polysaccharides are carbohydrates made up of bonded sugar molecules. Starch itself can be composed of one of two types of polysaccharides.
Amylopectin has many branches, with a greater surface area for digestion. Amylopectin breaks down rapidly, increasing blood sugar and insulin.
Amylose consists of a straight chain, which reduces the exposed surface area for digestion. Amylose is the most common polysaccharide found in resistant starch foods.
Compared to amylopectin, amylose is less likely to increase blood sugar and subsequently insulin.
Resistant starch is also lower in calories than other starches due to its ability to resist being fully digested. Per gram, the average starch will yield approximately 4 calories.
In comparison, only approximately 2 calories per gram is extracted from resistant starch. Foods high in resistant starch are better alternatives to other high-starch foods if you are attempting to lose weight.
Resistant starch is found naturally in certain grains and seeds. It is also available in fruits and vegetables like bananas and potatoes.
However, many grain-based products available today are heavily processed. For example, cereal bars are a popular alternative to oats. Potato chips are eaten more frequently than potatoes.
This dilutes the quality and amount of resistant starch we consume. Resistant starch is ideally found in whole, unprocessed foods. (Source)
Health Benefits Of Resistant Starch
Studies have associated resistant starch consumption with metabolic changes. These can benefit your health in a variety of ways. (Source)
Foods that are high in resistant starch can improve gut health, which is important to your general well-being. When resistant starch is fermented in the large intestine, butyrate is one of the SCFA produced.
Butyrate is the ideal source of fuel for the cells lining the colon, and may also enhance blood circulation. The health of these cells is crucial to maintaining a healthy, strong bowel.
Butyrate is absorbed into the bloodstream through the colon, and possesses anti-inflammatory properties. Butyrate’s ability to reduce inflammation is being researched for treating chronic bowel diseases.
Regular portions of resistant starch can also increase the type amount of good bacteria within the gut, supporting populations of healthy microflora that improve gut function.
Countries such as Japan and India have extremely low rates of bowel cancer. This may be due to high rates of resistant starch consumption, as fiber consumption in these regions is typically low.
Despite being a starch, resistant starch’s unique properties can help improve insulin sensitivity. One study monitored the effect of regular resistant starch consumption on men who were overweight or obese.
The subjects consumed between 15-30 grams on a daily basis. At the end of the study, insulin resistance had improved significantly.
In fact, subjects’ insulin resistance had improved the same way it would have if they had lost up to 10 percent of their body weight.
Since resistant starch has positive impacts on your blood sugar, it can also help promote weight loss. Resistant starch provides the fullness of starch with fewer calories. (Source)
The benefits of resistant starch on blood glucose levels are long-lasting. Studies have revealed that resistant starch has a “second meal effect”.
This means that it has the ability to lower blood glucose response at the next meal you have after eating resistant starch. (Source)
Types Of Resistant Starch
There are four types of resistant starch. Each type can be found in a certain group of foods.
Except for Type 3 resistant starch, uncooked and raw foods contain higher rates of resistant starch. This is because exposure to heat causes starch to turn gelatinous and become easier to digest.
The first type of resistant starch is physically inaccessible. Digestive enzymes cannot break this type of starch down.
Type 1 resistant starch is found in:
- Whole grains (i.e. oatmeal, whole-wheat bread)
- Partially milled grains (i.e. white rice)
The second type of resistant starch consists of resistant granules. This type contains high quantities of amylose, and is inherently impervious to digestion.
Type 2 resistant starch is found in:
The third type of resistant starch is retrograded. This type is found in starchy foods that have been cooked and then cooled down.
When the starch is subjected to heat and then cold, it changes form and becomes resistant.
Type 3 resistant starch is found in cooked/cooled:
- Certain legumes (i.e. white beans and lentils)
The fourth type of resistant starch is chemically modified. This form of resistant starch is isolated and chemically altered to include in processed foods.
Type 4 resistant starch is found in:
- Processed foods
- Synthetic resistant starch products (Source)
How To Eat Resistant Starch
The optimal amount of resistant starch to consume per day and reap health benefits is between 15 and 30 grams.
This is the equivalent of several tablespoons worth of potato starch. Proceed carefully when you begin to include resistant starch into your diet.
At first, you may experience some disruptive gastrointestinal symptoms (i.e. bloating). This is normal as the flora in your gut adapts to regular doses of resistant starch. (Source)
It is preferable to get your daily dose of resistant starch from whole foods in their raw form. For example, use raw oatmeal to make energy bars.
Potatoes contain retrograded starch when they are cooked and then cooled. Cooked potatoes can contain up to 57 percent more resistant starch if left in the fridge for a day.
Bananas that are still green can be blended into smoothies or eaten as they are. Legumes such as lentils and white beans can make tasty dishes. (Source)
With all the health advantages, begin including resistant starch in your diet today!
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