Micronutrients  are essential dietary elements required in varying quantities throughout life to serve metabolic and physiological functions.
* Dietary minerals, such as copper and iron, are elements native to Earth, and cannot be synthesized. They are required in the diet in microgram or milligram amounts. As plants obtain minerals from the soil, dietary minerals derive directly from plants consumed or indirectly from edible animal sources.
* Vitamins are organic compounds required in microgram or milligram amounts. The importance of each dietary vitamin was first established when it was determined that a disease would develop if that vitamin was absent from the diet.