Final answer:
A protein bar is not a dietary supplement because it is generally used as a food replacement or snack and provides significant caloric content, unlike herbal diet pills, vitamins, or mineral supplements that provide specific nutrients.
Step-by-step explanation:
The item that would NOT be considered a dietary supplement is a protein bar. Dietary supplements are intended to provide nutrients that may not be consumed in sufficient quantities. Supplements usually come in the form of pills, capsules, powders, or liquids and are focused on providing specific nutrients like vitamins, minerals, amino acids, or herbs, not a significant amount of caloric content or meal replacement as protein bars might.
A herbal diet pill, a vitamin E supplement, and a chewable calcium tablet are all directly aimed at supplementing the diet by providing specific nutrients or compounds that might be deficient or needed in additional quantities for health.