Manganese. Ⅰ. Nutritional intakes, nutritional and toxicological standards - are there health risks?

摘要

Due to a lack of sufficient data, instead of a recommended dietary allowance (RDA), a provisional daily dietary manganese intake of 2-5 mg is recommended by the Food and Nutrition Board of the National Research Council (NRC) in the USA and by the Deutsche Gesellschaft fuer Ernaehrung (DGE) in Germany for adults. The nutritional and toxicological standards for manganese calculated by the EPA are also based on limited dietary intake information. This leads to the conflicting situation that the calculated LOAEL for water of 4.2 mg Mn/day is within the recommended range of 2-5 mg Mn/day. The normative requirement of humans to manganese remains to be determined. The same is true for the absorption rate of manganese. The biochemical mechanisms which govern essentiality, deficiency and toxicity of manganese are complex and their details still largely unknown. Normally, a balanced diet, does not lead to Mn intoxication or Mn deficiency. However, manganese deficiency and toxicity may develop under special diets and health conditions. Potential deficiency examples are low intake and/or low absorption of manganese, low MnSOD activity, high iron supply, whereas toxicity examples may include vegetarian diet, manganese supplementation, iron deficiency, anemia, biliary and hepatic dysfunction.