We know far less about manganese than many other minerals. Like many minerals it serves as a cofactor for a number of enzymes that are discussed in more detail below.
The enzyme superoxide dismutase uses manganese as a cofactor to convert superoxide to hydrogen peroxide as shown below.
In addition, both the enzymes involved in the gluconeogenesis oxaloacetate workaround use manganese as cofactors as shown below.
One enzyme in the urea cycle uses manganese as a cofactor.
Enzymes critical to the production of proteoglycans, which are essential components of cartilage and bone, use manganese as a cofactor5.
Absorption of manganese is not well understood but is believed to be pretty low (<5%). It is mainly excreted (90%) through bile/feces5. Deficiency and toxicity of manganese is extremely rare. The deficiency is so rare in humans that there isn't much information available on the symptoms of the condition. Symptoms in those who were deliberately made deficient include vomiting, dermatitis, changes in hair color, & skeletal defects5. Toxicity symptoms include neurological disorders similar to schizophrenia and Parkinson's disease. In Chilean miners exposed to Mn-containing dust the toxicity was named Manganese Madness7,8. Some research suggests manganese toxicity is associated with iron deficiency because low iron levels allows for increased absorption of manganese9.
- Gropper SS, Smith JL, Groff JL. (2008) Advanced nutrition and human metabolism. Belmont, CA: Wadsworth Publishing.
- Stipanuk MH. (2006) Biochemical, physiological, & molecular aspects of human nutrition. St. Louis, MO: Saunders Elsevier.
- Shils ME, Shike M, Ross AC, Caballero B, Cousins RJ, editors. (2006) Modern nutrition in health and disease. Baltimore, MD: Lippincott Williams & Wilkins.
- Sigel A, Sigel H, Sigel RKO. (2013) Interrelations between Essential Metal Ions and Human Diseases, Metal Ions in Life Sciences. Springer, Netherlands.