Manganese functions as an enzyme activator and as a component of metalloenzymes (an enzyme that contains a metal ion in its structure).
Excellent food sources of manganese include mustard greens, kale, chard, raspberries, pineapple, romaine lettuce, collard greens and maple syrup.
Manganese activates the enzymes responsible for the utilization of several key nutrients including biotin, thiamin, ascorbic acid, and choline. It is a catalyst in the synthesis of fatty acids and cholesterol, facilitates protein and carbohydrate metabolism, and may also participate in the production of sex hormones and maintaining reproductive health.
In addition, manganese activates the enzymes known as glycolsyltranserferases and xylosyltransferases, which are important in the formation of bone. It has also been theorized that manganese is involved in the production of the thyroid hormone known as thyroxine and in maintaining the health of nerve tissue.
A component of metalloenzymes
Manganese has additional functions as a constituent of the following metalloenzymes:
- Arginase, the enzyme in the liver responsible for creating urea, a component of urine
- Glutamine synthetase, an enzyme involved in the synthesis of glutamine
- Phosphoenolpyruvate decarboxylase, an enzyme that participates in the metabolism of blood sugar
- Manganese-dependent superoxide dismutase, an enzyme with antioxidant activity that protects tissues from the damaging effects of free radicals.This enzyme is found exclusively inside the body's mitochondria (oxygen-based energy factories inside most of our cells).
What are deficiency symptoms for manganese?
Because manganese plays a role in a variety of enzyme systems, dietary deficiency of manganese can impact many physiological processes. In experimental animals, manganese deficiency causes impaired growth, skeletal abnormalities, and defects in carbohydrate and fat metabolism.
In addition, offspring of experimental animals fed manganese-deficient diets develop ataxia, a movement disorder characterized by lack of muscle coordination and balance. This condition is caused by poor development of the otoliths, the structures in the inner ear that are responsible for equilibrium.
In humans, manganese deficiency is associated with nausea, vomiting, poor glucose tolerance (high blood sugar levels), skin rash, loss of hair color, excessive bone loss, low cholesterol levels, dizziness, hearing loss, and compromised function of the reproductive system. Severe manganese deficiency in infants can cause paralysis, convulsions, blindness, and deafness.
It is important to emphasize, however, that manganese deficiency is very rare in humans, and does not usually develop unless manganese is deliberately eliminated from the diet. In addition, it has been suggested that magnesium substitutes for manganese in certain enzyme systems if manganese is deficient, thereby allowing the body to function normally despite the deficiency.
How do cooking, storage, or processing affect manganese?
Significant amounts of manganese can be lost in food processing, especially in the milling of whole grains to produce flour, and in the cooking of beans. Three and one half ounces of raw navy beans, for example, start out with about 1 milligram of manganese. This amount drops by 60% to 0.4 milligrams after cooking.
What factors might contribute to a deficiency of manganese?
Poor dietary intake of manganese appears to be the most common cause of manganese deficiency. However, other factors can contribute to a need for more manganese. Like zinc, manganese is a mineral that can be excreted in significant amounts through sweat, and invididuals who go through periods of excessive sweating may be at increased risk for manganese deficiency.
Proper formation of bile in the liver, and proper circulation of bile through the body are also required for manganese transport. As a result, individuals with chronic liver or gallbladder disorders may need more dietary manganese.