Manganese(2+)

Mn²⁺ is an essential cofactor and activator for many enzymes that regulate biological functions and processes, such as oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. These enzymes include polysaccharide polymerase, liver arginase, cholinesterase, pyruvate carboxylase, and Mn superoxide dismutase (MnSOD). These enzymes regulate immune function, metabolism, growth potential, hemostasis, mitochondrial homeostasis and antioxidant function, and neuronal function.

When orally administered, manganese (Mn) is reported to be readily absorbed through the intestinal tract: about 3–5% of dietary Mn is absorbed as Mn2+ and Mn4+. Under conditions of minimal intake, 20 mcg Mn/day is retained following intravenous administration. Assays for manganese in whole blood result in concentrations ranging from six to 12 mcg/Mn/L.

Excretion of manganese occurs mainly through the bile, but in the event of an obstruction, ancillary excretion routes include pancreatic juice or return into the lumen of the duodenum, jejunum, or ileum. Urinary excretion of manganese is negligible.

Mn can cross the blood-brain barrier. Manganese is widely distributed but concentrates in mitochondria-rich tissues such as the brain, kidney, pancreas, and liver.