Manganese (Mn) is a component of several enzyme systems, including manganese-specific glycosyltransferases and phosphoenolpyruvate carboxykinase, and is essential for normal bone structure. Intake varies greatly, depending mainly on the consumption of rich sources, such as unrefined cereals, green leafy vegetables, and tea. The usual intake of this mineral is 2 to 5 mg/day, and absorption is 5 to 10%.

One case of human manganese deficiency was reported in a volunteer who received a purified diet containing 0.1 mg/day of manganese. He developed transient dermatitis, hypocholesterolemia, and an increase in alkaline phosphatase levels. He lost about 60% of his estimated body pool of manganese in 2 wk, but no further losses occurred during an additional 4 wk on a deficient diet. Manganese deficiency has not been documented in the clinical literature.

Manganese poisoning is usually limited to people who mine and refine ore; prolonged exposure causes neurologic symptoms resembling parkinsonism or Wilson's disease.