Which of the following is NOT a role of carbohydrates in the body?

Carbohydrates play several crucial roles in the body, and understanding these roles helps clarify their importance in nutrition. One primary function of carbohydrates is to serve as an energy source, particularly for the brain, which relies heavily on glucose, a simple carbohydrate. This makes option A a well-established role of carbohydrates.

Maintaining gut health is another vital role attributed to carbohydrates, especially through dietary fiber. Fiber, which is a type of carbohydrate, supports digestive health and promotes regular bowel movements, highlighting the validity of option C.

Option D relates to red blood cell function, where certain carbohydrates can be involved indirectly through energy provision; however, it is not a direct role as compared to the others.

In contrast, while carbohydrates can support certain metabolic processes, they do not carry vitamins. This function is typically associated with fats, as certain vitamins (A, D, E, and K) are fat-soluble and thus require fats for absorption and transportation in the body. Therefore, the assertion that carbohydrates carry vitamins is not accurate, which establishes option B as the correct choice in identifying a role that carbohydrates do not fulfill in the body.