Components of food required by the body in small amounts for growth and health maintenance are nutrients that can be converted into another nutrient. These are chemical substances, including many vitamins, that activate specific enzymes. They are also chemical substances that prevent or repair damage to cells caused by exposure to free radicals. They are primarily stored in body fat and the liver and can only be stored in the body in small amounts. Low-grade inflammation that lasts weeks, months, or years is also a component of food. Lastly, there are chemical substances that are missing an electron, known as coenzymes and antioxidants.