Resistant starches — are a special form of carbohydrates that differ from regular starch in that they are not digested in the human small intestine. Instead, they pass further into the large intestine, where they can interact with the microbiota or be excreted with little metabolic involvement. Because of this, resistant starches are often considered a functional component of nutrition rather than a source of energy.
What is resistant starch
Resistant starch (RS) — is starch that is resistant to the action of digestive enzymes. Unlike regular starches, it does not raise blood glucose levels directly and is not used by the body as a quick energy substrate. Its physiological behavior is closer to dietary fibers, although chemically it remains starch.
Main types of resistant starches
RS2 — naturally resistant starch
RS2 is found in products where starch granules are physically inaccessible to enzymes. Classic examples — are green bananas and raw potatoes. In its natural form, this type of starch is virtually indigestible, but its resistance is partially lost during thermal processing.
RS3 — retrograded starch
RS3 forms after cooking and subsequent cooling of starch-containing products (potatoes, rice). During the cooling process, the structure of the starch changes, and part of it becomes resistant to digestion. This is the most commonly encountered form of resistant starch in a typical diet.
RS4 — chemically modified starch
RS4 — are industrially modified starches that are resistant to digestion due to chemical bonds. They are used in the food industry as functional ingredients and technological additives. From a physiological perspective, they are not considered “natural” products.
Physiological action of resistant starches
Upon reaching the large intestine, some resistant starches can be fermented by the microbiota, producing short-chain fatty acids. However, the degree and significance of this process vary greatly among individuals and depend on the composition of the microbiota, diet, and overall gastrointestinal health.
It is important to note that resistant starches are not an essential component of nutrition. There are sustainable dietary patterns (including low-carbohydrate and carnivore approaches) where gut health is maintained without the involvement of fermentable fibers and starches — through fats, bile, and adaptation of the digestive system.
Resistant starches and blood sugar levels
Due to their resistance to digestion, resistant starches do not cause a sharp rise in glucose and insulin levels. However, their influence on carbohydrate metabolism is indirect and depends on the dietary context. In a mixed diet, they can reduce the glycemic load of a meal, but in low-carbohydrate diets, their role is minimal.
Role in appetite control and body weight
Some studies link resistant starches to increased feelings of fullness, but this effect is not universal. It is primarily expressed in high-carbohydrate diets and does not play a key role in diets where satiety is determined by fats and proteins.
Practical conclusion
Resistant starches — are an optional, context-dependent component of nutrition. They can be used in mixed diets as a technological or functional element, but they are not a physiological necessity for gut health, metabolism, or blood sugar control.
Their appropriateness is determined individually: by the type of diet, the state of the digestive system, and nutritional goals. For some people, they are neutral, for others — excessive, and in some cases, they may even cause discomfort.
