Manganese (Mn)

Manganese is an essential nutrient. An adult contains around 10-20 mg of manganese that is evenly distributed throughout the body. Only around five per cent of dietary manganese is absorbed, possibly by means of the same mechanisms as those involved in the uptake of iron. Manganese is mainly involved in different enzymatic systems such as pyruvate carboxylase and superoxide dismutase (SOD) that support the metabolism of macronutrients such as carbohydrate, protein, and fat and also work by neutralising free radicals.

Functions and importance for

• Energy turnover
• Antioxidant function
• Bones and connective tissue

Deficiencies and poor utilisation may be caused by

Rarely seen but may occur in connection with:

• Large iron intake that inhibits the uptake of manganese

Deficiency symptoms

Apparently, we get sufficient amounts of manganese from our diet. Dietary deficiency symptoms have only been observed in one person who took part in a scientific study. The symptoms observed included:

• Weight loss
• Skin rash
• Nail and hair changes

Epileptics may have low blood levels of manganese.
Disturbances in the carbohydrate metabolism and growth and fertility disturbances have been observed in animal studies.

Sources

Mainly whole-grain, nuts, seeds, kernels, almonds, parsley, and other herbs. Beans, garlic, other vegetables, and fruit.

Manganese content in mg per 100 grams

Recommended daily allowance (RDA)

Adults: 11 years of age and older: 2 mg
Children: 1-10 years of age: 1.2 mg

Increased need

Not described

Overdosing - side effects

Not observed with dietary intake or the use of supplements. However, inhalation of large amounts of manganese as an occupational hazard of certain job types (mining, agricultural crop spraying) may cause manganese to accumulate in nerve cells (astrocytes), resulting in the following symptoms (that resemble those observed in Parkinson's disease):

• Stiff muscles
• Trembling - even during rest
• Slow movements

Interactions

Manganese and many other metals reduce the uptake of tetracyclines (a type of antibiotics) by as much as 50%. For that reason, tetracycline drugs and manganese supplements should be ingested with at least a three-hour interval.

Important information

Manganese is often accompanied by iron in drinking water. A typical signs of this is that the water is ocher-coloured and has a characteristic metal taste. As the two minerals discolour laundry and bathroom sanitary ware it is common practice to remove them from the water. The maximum permitted manganese level in drinking water is 0.05 mg/l.