Starch is a complex carbohydrate found in plant foods, and serves as their energy storage. Starch is made of three or more (usually several hundreds or thousands) glucose units bonded together. It doesn’t contain fructose. (1, 2)
Most of the starch in our diet is obtained from:
- Cereal grains and related products such as wheat, rice, corn, oats, breads or pasta;
- Tuber vegetables such as potatoes, sweet potatoes, yams or cassava;
- Fruit such as bananas or plantains.
Starches can be:
- Refined (fibre and some nutrients are deliberately removed) such as white rice, bread or pasta;
- Unrefined (nutrients are not deliberately removed) such as brown rice, wholemeal bread, wholemeal pasta, potatoes or bananas.
Starches can also be of a high, medium or low Glycemic Load (GL). GL measures how a given food raises blood glucose level, with “high” causing the greatest increase. (3)
Starch molecules generally take longer to digest than simple sugars, therefore, providing a more sustained source of energy.
However, the rate of digestion depends on the concentration of starch in the food, amount of fibre that comes with it, to what extent the starches are broken down by various processes.
This includes: removing the outer fibrous layer from brown rice and processing it to white rice flour or the difference between boiling a potato vs boiling a carrot with less starch, lower GL and more fibre.