The primary role of manganese is as a coenzyme in a variety of metabolic processes. It helps the body produce energy from foods, and it is also involved in thyroid function and bone formation. In addition, manganese is involved in immune system function, and it can help to heal muscular strains and sprains.
Manganese also supports mineral transport and absorption, which keeps skin, bones and cartilage healthy.
One important role of manganese as a coenzyme is to support the enzyme superoxide dismutase (SOD), a powerful antioxidant enzyme that functions to prevent inflammation and other damage from free radicals that result from oxidative stress in the body. Manganese is essential to the proper function of SOD, and manganese supplements may boost the antioxidant activity of this important enzyme.
Research to determine other possible uses of manganese supplements has found that the mineral may help to improve cognitive symptoms as well as reduce irritability and nervousness. Manganese may also help people with diabetes, and it may reduce fatigue and weakness in some people as well. People with epilepsy and arthritis may also benefit from manganese supplements.
The daily requirement of manganese for adults is approx. 2 mg per day (1.8 mg for women; 2.3 mg for men). Good food sources include whole grains, dried fruit, and green leafy vegetables. Manganese is present in a wide variety of other foods as well.
Since manganese requirements are relatively low and the mineral is widespread in foods, manganese deficiency is almost nonexistent in humans. However, several factors affect manganese absorption and may interfere with proper utilization of the mineral. For example, iron and calcium inhibit manganese absorption, so people who use supplements of these minerals may need to take extra manganese as well.
Signs that more manganese may be needed in the diet include skin problems, premature graying of hair, mental confusion, and insufficient growth of nails and hair.
Manganese supplements are available as manganese sulfate or manganese chloride, as well as chelated minerals, such as manganese picolinate or manganese gluconate. It is generally thought that the chelated minerals are the easiest for the body to absorb.
Though manganese toxicity is rare, in some cases, psychiatric symptoms, including dementia, have been associated with excessive manganese intake.
Manganese toxicity is most likely to occur where the environment is contaminated with manganese and not from dietary or supplement intake. For example, miners who work in areas where large amounts of manganese dust are present have shown symptoms of brain disease and other nervous system disorders. Nonetheless, because of the potential for toxicity, taking more than 100% of the daily recommended value (2 mg – a typical amount found in a multivitamin) is not recommended.