Manganese is a metallic trace mineral essential to human nutrition. The average human body contains 10 to 20 mg of manganese, most of which is found in the liver, bones, kidneys, and pancreas. Manganese acts as a cofactor in many enzymatic processes throughout the body, and plays important roles in bone, cartilage, and skin formation, glucose and cholesterol metabolism, and thyroid and pancreatic function. It also contributes to the body's antioxidant defense mechanisms. Supplemental forms of manganese include manganese salts (sulfate or chloride) and chelates such as picolinate and gluconate. Supplemental manganese is usually found in multi-vitamin/mineral formulas rather than as an individual supplement.
Manganese is found in a wide variety of foods, but concentrations vary in relation to soil manganese levels. Good sources of manganese include whole grains, nuts, seeds, and green leafy vegetables.
The Reference Daily Intake (RDI) for manganese is 2 mg per day. As much as 20 mg (as found in some high potency supplements) appears to be safe. Manganese toxicity is generally confined to populations such as miners and metal workers with chronic exposure to manganese pollution. Manganese intoxication can cause neurological damage, impaired memory, tremors, and mood disturbances.