Complex carbohydrates require a prolonged digestion process to be broken down into glucose, thereby helping to maintain proper blood sugar levels.

Complex carbohydrates are large molecules made up of sugar units that are linked together in long chains. They are found in foods such as whole grains, legumes, and vegetables. Because of their complex molecular structure, these carbohydrates take longer for the body to break down into glucose, the simple sugar that the body uses for energy.

The digestion process of complex carbohydrates starts in the mouth, where enzymes in saliva begin to break down the molecules. The process continues in the stomach and primarily in the small intestine, where most of the absorption takes place. Pancreatic enzymes and brush border enzymes of the small intestine work to further break down the chains into individual glucose molecules.

The glucose is then absorbed into the bloodstream, raising blood sugar levels. However, because the breakdown and absorption of complex carbohydrates is gradual, the increase in blood sugar is slower and more sustained as compared to the consumption of simple sugars, which can cause a rapid spike in blood sugar levels. This prolonged digestion helps in maintaining proper blood sugar levels, avoiding the sharp peaks and troughs that may be experienced after eating simple carbohydrates.

Stabilizing blood sugar is important because it ensures a constant supply of energy to the body's cells and helps prevent both the rapid highs and the subsequent rapid lows in blood sugar that can lead to feelings of fatigue, irritability, and craving for more sugar.