What defines a nutrient?

A nutrient is defined as a substance that the body eats, digests, and absorbs in order to maintain proper functioning and overall health. This definition focuses on the role of nutrients in supporting bodily processes such as growth, energy production, and cellular repair. Nutrients are essential for various physiological functions, and they provide the necessary building blocks for the body to operate smoothly.

While some of the other options mention important concepts, they do not accurately describe what nutrients are. For example, a substance causing illness or a chemical element alone does not encompass the complete role or definition of nutrients. Likewise, describing a nutrient as a type of food that is calorie-free is misleading since nutrients can be found in foods of varying caloric content. Instead, the primary function of nutrients is to nourish the body, highlighting the importance of their consumption through diet.