Starch — is a complex carbohydrate, a polymer of glucose, which is widely distributed in nature and found in various plants. Depending on the source, starch can have different physical and chemical properties.
The main sources of starch in the diet include:
- Potatoes;
- Rice;
- Wheat;
- Corn;
- Legumes.
Starch serves as the main storage carbohydrate, providing energy sources for many organisms.
Structure and Properties
Starch is a polymer made up of many glucose molecules linked together. Its structure includes two main components: amylose and amylopectin.
- Amylose – a linear polymer that makes up about 20-30% of starch. It is found in sources such as potatoes, corn, and rice.
- Amylopectin – a branched polymer that constitutes 70-80% of starch. It can be found in legumes, oats, and barley.
Impact on Health and Diets
There are two types of starch: resistant starch and soluble starch.
Resistant Starch
Resistant starch is not digested in the small intestine, reaching the large intestine unchanged. There, it serves as dietary fiber, which contributes to:
- Improving gut health: it is a nutrient source for beneficial microflora (prebiotic).
- Reducing appetite: due to the slow release of energy, it increases the feeling of fullness.
- Controlling blood sugar levels: it has minimal impact on the glycemic index of foods, which is beneficial for diabetes.
Sources of resistant starch:
- Unripe bananas (not suitable for keto due to high carbohydrate content).
- Potatoes or rice after cooling (not suitable for keto).
- Non-starchy vegetables and nuts (allowed in moderation on keto).
Soluble Starch
Soluble starch is easily digested and quickly raises blood sugar levels, making it less beneficial for health, especially in diabetes or when trying to control weight.
It is found in:
- white bread, baked goods, pasta;
- potatoes, corn, rice.
On a keto diet, such products are excluded due to their high carbohydrate content.
How Starch Changes from One Type to Another
Starch can convert from soluble to resistant during thermal processing and subsequent cooling.
For example, hot potatoes contain more soluble starch, but upon cooling, some of the starch becomes resistant.
However, even in this form, potatoes and rice remain high-carbohydrate foods, which is incompatible with keto.
