Evidence of Concerns for Manganese Deficiencies?
Manganese Deficiency and Toxicity: Are High or Low Dietary Amounts of Manganese Cause for Concern?
“Although much remains to be learned of the functions of Mn, at present there are only a few vaguely described cases of Mn deficiency in the medical literature.”
“There may be reasons, however, to be concerned about Mn toxicity under some very specialized conditions. Increasing numbers of young people are adopting a vegetarian lifestyle, which may greatly increase Mn intake. Iron deficiency may increase Mn absorption and further increase the body burden of Mn, especially in vegetarians.”
Summary statement: “Would such a combination of events predispose substantial numbers of people to chronic Mn toxicity? At present, there is no definite proof of this occurring, but given the state of knowledge at the present time, more studies with longer time frames and more sensitive methods of analysis are needed.”
Manganese Neurotoxicity: A Focus on the Neonate
“While Mn deficiency is extremely rare in humans, toxicity due to overexposure of Mn is more prevalent. The brain appears to be especially vulnerable.”
“Research projects that examine…mechanisms of Mn neurotoxicity in the neonatal brain are scant.”
Summary statement: “We briefly review some of the mechanisms of Mn neurotoxicity and conclude with a discussion of ripe areas for research in the underreported area of neurotoxicity. No data are available in terms of assessing the neurological effects of Mn-exposure during early life and long term consequences of this exposure.”
Manganese Exposure Alters Extracellular GABA, GABA Receptor and Transporter Protein and mRNA Levels in the Developing Rat Brain
“Unlike other essential trace elements (e.g. zinc and iron) it is the toxicity of manganese that is more common in human populations than its deficiency.”
“Data suggest alterations in dopamine biology may drive the effects associated with Mn neurotoxicity, though recently GABA has been implicated.”
“In addition, iron deficiency, a common nutritional problem, may cause disturbances in neurochemistry by facilitating accumulation of Mn in the brain.”
Summary statement: “These data suggest that Mn exposure results in an increase in extracellular GABA concentrations via altered expression of transport and receptor proteins, which may be the basis of the neurological characteristics of manganism.”