What role do vitamins play in the body?

Vitamins primarily function as coenzymes in the body. This means they assist in various biochemical reactions, helping enzymes to facilitate chemical reactions crucial for metabolism and other physiological functions. For instance, many B vitamins serve as essential coenzymes in energy production and the metabolism of carbohydrates, fats, and proteins. They enable the enzymes that catalyze these reactions to function more effectively, thereby supporting overall health.

The other options do not accurately reflect the role of vitamins. While vitamins are important for overall health, they do not directly provide energy; that role primarily belongs to macronutrients like carbohydrates, proteins, and fats. Additionally, vitamins themselves do not contribute to muscle building, which is largely the function of proteins and amino acids. Finally, vitamins are not a source of carbohydrates; instead, they are organic compounds that complement the action of macronutrients but do not serve as a direct energy source.