Which nutrient is the most abundant component of the human body?

Water is the most abundant component of the human body, constituting about 60% of an adult's body weight and making it critical for numerous physiological processes. It serves as a solvent, facilitating chemical reactions, transporting nutrients and waste products, regulating body temperature, and maintaining cell structure. Additionally, water is essential for digestion and absorption of nutrients, as well as for maintaining blood volume and pressure.

Unlike the other options, which are important macronutrients in the diet, water is not classified as a nutrient in the traditional sense but is vital for life. For example, while proteins play critical roles in cell structure and function, they do not make up the majority of the body's composition. Carbohydrates and fats are also key sources of energy but are present in smaller proportions compared to water. Their roles are primarily focused on energy provision and storage rather than serving as the principal component of body composition.