Because of our depleted soil, many fruits and vegetables do not contain the same amount of micronutrients (vitamins and minerals) that they used to. Supplementing can be helpful to reach adequate amounts of nutrients for immunity, energy, cellular metabolism, and basically every function of our cells relies on vitamins to operate. In one of my grad classes, I'm doing a lot of research on a vitamin that is not found in fruits and vegetables: Vitamin D, the "sunshine" vitamin.