Manganese is an essential nutrient. It is found as a coenzyme in many biological processes. They include macronutrient metabolism, bone formation, and free radical immune system. It is a very important component in lots of proteins and enzymes. The human body contains about 12 mg of manganese. Manganese is found in the bones, liver, brain and kidneys. In the human brain, the manganese is bound to manganese metalloproteins.