Which of the following substances is NOT known to aid in digestion?

The substance that is not known to aid in digestion in the context of the question is protein. While protein is an essential macronutrient necessary for various bodily functions, including the repair and building of tissues, it is not directly associated with aiding the digestive process itself. Instead, digestion involves the breakdown of food into smaller molecules that the body can absorb, and proteins are generally broken down into amino acids by enzymes during this process.

On the other hand, fiber is well-known for its role in aiding digestion by promoting regular bowel movements and improving gut health. It helps in the movement of food through the digestive tract and can prevent constipation.

Glucose, as a simple sugar, is an energy source that is easily absorbed by the body, and while it doesn’t aid in digestion in the same way fiber does, it is a product of carbohydrate digestion that provides energy.

Sucrose, another form of sugar, also has an important role in the digestive process as it is broken down into glucose and fructose, which can be readily absorbed by the body.

Understanding the functions of each substance in relation to digestion can clarify why protein is not characterized as an aid in this specific aspect, despite its overall importance in nutrition.