Final answer:
Vitamins contain 0 kcal/g because they are essential compounds required for normal metabolism but do not provide energy in the form of calories. Macros like fats, carbohydrates, and proteins are the ones that provide caloric energy.
Step-by-step explanation:
Vitamins are organic compounds that are essential in small amounts for the maintenance of normal metabolism and do not provide calories. The question "Vitamins contain _______ kcal/g." can be answered as 0, which means that vitamins do not supply any energy in the form of calories. Energy-providing nutrients include fats, carbohydrates, and proteins, with fat providing 9 kcal/g, carbohydrates providing 4 kcal/g, and proteins also providing 4 kcal/g. Vitamins such as Vitamin A, Vitamin C, and Vitamin E, to name a few, provide no calories but are crucial for many bodily functions, including supporting the immune system, acting as antioxidants, and aiding in bone health.