Which concise statement best distinguishes a true vitamin from a vitamin-like (conditionally essential) nutrient?

True vitamins are organic micronutrients that the body can synthesize reliably under all physiological states and therefore never need to be eaten; vitamin-like nutrients are always obtained exclusively from foods and must be eaten daily to avoid deficiency and organ failure.

True vitamins are macronutrients providing calories and structural substrates that must be eaten for energy under all circumstances, whereas vitamin-like nutrients are only used in signaling and are irrelevant to metabolism except under starvation.

True vitamins are required from the diet under all circumstances; vitamin-like nutrients are usually synthesized endogenously and only required from the diet under special conditions.

True vitamins are inorganic mineral elements required for enzyme function and cannot be synthesized, while vitamin-like nutrients are synthetic pharmaceuticals that mimic vitamin action and are required only in therapeutic contexts.