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Manganese

Manganese

Description

The adult human body contains about 10 to 20 milligrams of manganese. Most of this is concentrated in the pancreas, bone, liver, and kidneys.

Manganese acts as a catalyst and a cofactor in many enzymatic processes involved in the synthesis of fatty acids and cholesterol. For example, manganese is an important cofactor in the enzymes necessary for mucopolysaccharide synthesis.

Manganese is also an essential cofactor of important enzymes active in the mitochondria, and in the synthesis of glycoproteins, which coat body cells and protect against invading viruses.

Mucopolysaccharide is an important constituent in both skeletal and cartilage structural matrix. Because of its role in mucopolysaccharide synthesis, manganese is important in skeletal and connective tissue development.

Many of the metabolic functions in which manganese is an important cofactor can use magnesium and manganese interchangeably.

Method of Action

Manganese is absorbed with about 4% efficiency from the intestines and is carried into, and in the blood by the protein transmanganin. Regulation of body manganese levels is controlled primarily through variable excretion, rather than absorption.

Manganese is essential for the enzymatic incorporation of xylose and galactose into glycoproteins. These glycoproteins are the cells natural barrier to invading viruses and coat every cell of the human body. Glycoproteins also make up the great majority of all secretory proteins.

Manganese and magnesium are used interchangeably in many enzymes as cofactors. Aminopeptidases, which break down protein structure, are secreted by intestinal mucosal cells for digestive purposes and utilize either magnesium or manganese as a cofactor element of their structures.

Manganese is an important constituent of activated arginase, an enzyme found in the liver, and mediates the conversion of arginine to urea. Manganese is a constituent of the enzyme pyruvate carboxylase, which plays an important role in gluconeogenesis: the conversion of various noncarbohydrate substances into glucose for subsequent use.

Manganese is also involved in the transfer of high energy phosphate groups by phosphotransferase enzymes. These enzymes are found in various metabolic pathways, including several steps of glycolysis.

Manganese tends to activate the lipid metabolizing enzyme lipoprotein lipase, otherwise called the "clearing factor."

Manganese seems to be important for the enzymatic activity of glycosyltransferases, which play a vital role in mucopolysaccharide synthesis. Impaired activity of these enzymes, due to manganese deficiencies, can result in abnormal cartilage formation. High calcium and phosphorus intake decreases manganese absorption. Excretion of manganese is through the intestine via bile.

Properties & Uses

Manganese, due to its role in connective tissue formation, has been used to help prevent and alleviate symptoms of arthritic conditions caused by inadequate or faulty connective tissue synthesis.

Manganese has also been found useful in controlling diabetes mellitus in some patients. Manganese supplementation can, in some cases, result in an overall decrease in blood sugar levels, concomitant with an increased storage of glycogen in the liver.

Manganese supplements are used in treatment of various schizophrenia disorders. Manganese and zinc supplements have been used to induce copper excretion in patients with dangerously high copper accumulation in the body.

Consequence of Deficiency

In humans, a deficiency in manganese has not been shown conclusively to be linked to any specific set of symptoms.

Animal studies have shown manganese deficiencies in animals can result in skeletal abnormalities and defective muscular coordination in offspring. This abnormality is linked to the impaired synthesis of mucopolysaccharides, which constitute the gelatinous material essential in the formation of bone and cartilage. However, reproductive dysfunction, impaired glucose tolerance, and disturbances in lipid metabolism can affect anyone suffering from deficiency.

This disorder of skeletal abnormality is frequently concomitant with defective muscular coordination, caused by abnormal development of otoliths. Otoliths are calcified structures of the inner ear responsible for maintaining coordinated reflexes and equilibrium. This disorder again appears to be a result of deficient mucopolysaccharide synthesis.

Toxicity Factors

Ingestion of large amounts of manganese may result in elevated concentrations in the liver, but there are no ill effects overall.

Ingestion of potassium permanganate can result in acute poisoning, with symptoms of capillary damage, jaundice, and tissue damage in the gastric, mucosa of the intestine.

Inhalation of manganese dust could result in manganese poisoning, with symptoms such as involuntary laughing, impotence, blurred speech, mask-like facial expression, hand tremors, and spastic gait. This poisoning has been noticed and documented primarily in manganese ore miners.

Recommended Dietary Allowance

RDA for adults:2.5 - 5 mg
RDA for children 13+:2.5 - 5 mg
RDA for children 10-13:2.18 mg
RDA for children 3-5:1.4 mg



The above is 1980 values for RDA.

For over thirty years, Recommended Daily Amounts has existed in the United Kingdom. It has been used to measure the adequacy of an individual's diet. However, in 1991 the Committee on Medical Aspects of Food Policy (COMA) gave forth a whole new set of figures upon the request of the Department of Health's Chief Medical Officer. Reference Nutrient Intake (RNI) is one of these sets collectively known as "Dietary Reference Values." RNI is an amount of a nutrient that is enough for almost every individuals, even someone who has high needs for the nutrient. This level of intake is, therefore, considerably higher than what most people would need. If individuals are consuming the RNI of a nutrient they are most unlikely to be deficient in that nutrient.

The COMA 1991 report does not give any RNI's for Manganese, but suggests safe intake lies above 1.4 mg per day for adults.

Food Sources

AsparagusAvocado
Baked beansBananas
Beef liverBeetroot
BlackberryCabbage
CarrotCauliflower
CoconutGreen pea
Green leafy vegetablesHoney
LettuceNuts
Oat flakesOlives
OystersPeanut butter
PineappleProcessed cheese - American
SpinachTea - black
Veal liverWhite bread (enriched)
Whole wheat



Abstracts

References

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