Manganese is a trace mineral that is present in tiny amounts in the body. It is found mostly in bones, the liver, kidneys, and pancreas. Manganese helps the body form connective tissue, bones, blood clotting factors, and sex hormones.
It also plays a role in fat and carbohydrate metabolism, calcium absorption, and blood sugar regulation.
Manganese is also necessary for normal brain and nerve function.
In biology, manganese ions function as cofactors for a large variety of enzymes with many functions.
Manganese enzymes are particularly essential in detoxification of superoxide free radicals in organisms that must deal with elemental oxygen.
Functions:
The human body contains approximately 15 to 20 mg of manganese, which is primarily found in the bones, liver, kidney, pancreas, adrenal and pituitary glands. It helps the body form connective tissue, blood clotting factors and sex hormones.
It functions as a cofactor to antioxidants and is necessary for the metabolism of carbohydrates, fat, amino acids and cholesterol.
It plays a role in calcium absorption, blood sugar regulation, bone health, wound healing and proper brain and nerve functions.
There is no specific evidence that manganese can prevent osteoporosis, but one study found that taking a combination of calcium, zinc, copper, and manganese helped lessen spinal bone loss in a group of post menopausal women.
People with arthritis tend to have low levels of SOD (an antioxidant that helps protect the joints from damage during inflammation). Some experts theorize that manganese may increase SOD levels, but there is no proof that it helps treat arthritis.
In one well designed clinical study, women who ate 5.6 mg of manganese in their diets each day had fewer mood swings and cramps related to premenstrual syndrome (PMS) compared to those who ate only 1 mg of manganese.
These results suggest that a manganese rich diet may help reduce symptoms of PMS. Another clinical study found that 46 patients with PMS found had significantly lower amounts of calcium, chromium, copper, and manganese in their blood.
Some studies seem to show that people with diabetes have low levels of manganese in their blood. But researchers don't know if having diabetes causes levels to drop, or whether low levels of manganese contribute to developing diabetes.
More studies are needed. One clinical study found that people with diabetes who had higher blood levels of manganese were more protected from LDL or "bad" cholesterol than those with lower levels of manganese.
What food Manganese is found in:
Foods rich in manganese include wheat germ, fruits such as grapes, kiwi, pineapples and berries;
vegetables like dark leafy greens, beets, sweet potatoes, celery, squash and carrots;
nuts and seeds; legumes;
soy products like tofu and tempeh;
egg yolks;
whole grains such as brown rice, oatmeal, raisin bran, quinoa, barley and spelt;
herbs and spices like peppermint, cinnamon, cloves and thyme; molasses; syrup and tea.
Refined grains only provide half the amount of manganese as whole grains.
Foods That Inhibit Manganese
Foods that contain phytic acid, such as beans, seeds, nuts, whole grains and soy products, or foods high in oxalic acid, such as cabbage, sweet potatoes, and cabbage, can moderately inhibit manganese absorption.
Cooking these foods may help neutralize this effect.
While tea is a good source of manganese, the tannins present in tea may slightly reduce its absorption.
Additionally, the intake of other minerals, including phosphorus, calcium and iron, has been found to limit the body's ability to retain manganese.
Sources of manganese in the diet
Contribution of food types to average daily intake of manganese
Food Type - mg/day
Cereal and cereal products - 1.2253 - of which white bread - 0.3515
High fibre and whole grain breakfast cereals - 0.188
Milk and milk products - 0.021
Meat and meat products - 0.167
Fish and fish dishes - 0.021
Vegetables, potatoes and savoury snacks - 0.4419
Fruits and nuts - 0.094
Sugar, confectionery and preserves - 0.094
Beverages - 0.188- of which tea - 0.146
Miscellaneous - 0.052
Mean intake from food - 2.31100
Mean intake from food and supplements - 2.31
Concentrations of manganese in 1994
Total Diet samples and estimated average intake
Food group / Mean Mn concentrations (mg/kg fresh weight):
Bread 8.0
Miscellaneous cereals 6.81
Carcase meat 0.14
Offal 2.8
Meat products 1.39
Poultry 0.17
Fish 1.14
Oils & fats 0.02
Eggs 0.31
Sugars & preserves 1.52
Green vegetables 2.01
Potatoes 1.94
Other vegetables 1.6
Canned vegetables 1.84
Fresh fruit 1.99
Fruit products 2.25
Beverages 2.71
Milk 0.03
Dairy produce 0.27
Nuts 14.9
What symptoms and disorders Manganese deficiency may cause:
A deficiency typically occurs only if manganese is eliminated from the diet. The most common cause of low manganese levels is a poor dietary intake.
Other factors include malabsorption, antacid or oral contraceptive use that interfere with its absorption, excessive sweating because large amounts of manganese is lost in sweating, excess iron, copper or magnesium because they deplete manganese, and chronic liver or gallbladder disorders, which raise intake requirements.
Deficiency Symptoms:
Manganese is involved in many different biochemical processes and can, therefore, adversely affect a number of systems throughout the body.
Low levels of manganese in the body can result in impaired glucose tolerance, altered carbohydrate and fat metabolism, skeletal abnormalities, bone demineralization and malformation, stunted growth, decreased serum cholesterol levels, skin rash and elevated blood calcium, phosphorus and alkaline phosphatase levels.
In addition, manganese deficiencies can result in infertility, seizures, weakness, nausea or vomiting, dizziness, hearing loss, iron-deficiency anemia, weak hair and nails and convulsions, blindness or paralysis in infants.
Problems related to excessive doses:
Manganese overexposure is most frequently associated with manganism, a rare neurological disorder associated with excessive manganese ingestion or inhalation.
Too much manganese in the diet could lead to high levels of manganese in the body tissues. Abnormal concentrations of manganese in the brain, especially in the basal ganglia, are associated with neurological disorders similar to Parkinson's disease. Early life manganese exposure at high levels, or low levels, may impact neurodevelopment.
Elevated manganese is also associated with poor cognitive performance in school children.
Manganese compounds are less toxic than those of other widespread metals, such as nickel and copper. However, exposure to manganese dusts and fumes should not exceed the ceiling value of 5 mg/m3 even for short periods because of its toxicity level.
Manganese poisoning has been linked to impaired motor skills and cognitive disorders.
Manganese in drinking water
Waterborne manganese has a greater bioavailability than dietary manganese. According to results from a 2010 study, higher levels of exposure to manganese in drinking water are associated with increased intellectual impairment and reduced intelligence quotients in school-age children.
Supplements and dietary intake of manganese together should not exceed 10 milligrams per day because of the risk of nervous system side effects. You should only take manganese supplements under the supervision of your doctor; that is especially true for children.
Recommended doses for people in the UK:
There are no recommendations on daily intake in the UK, but the World Health Organisation notes a daily intake of 2.5 mg as the absolute minimum requirement. The USA recommendations are 2.3 mg for men and 1.8 mg for women.
Most people in the UK are not likely to suffer from Manganese deficiency. Tea is a major source of Manganese and supplies up to half the daily UK intake.