Manganese and Chronic Diseases

Low dietary manganese or low levels of manganese in blood or tissue have been associated with several chronic diseases. Although manganese insufficiency is not currently thought to cause the diseases discussed below, more research may be warranted to determine whether suboptimal manganese nutritional status contributes to certain disease processes.

Osteoporosis

Women with osteoporosis have been found to have decreased plasma levels of manganese and an enhanced plasma response to an oral dose of manganese, suggesting they may have lower manganese status than women without osteoporosis. A study in healthy postmenopausal women found that a supplement containing manganese (5 mg/day), copper (2.5 mg/day), and zinc (15 mg/day) in combination with a calcium supplement (1,000 mg/day) was more effective than the calcium supplement alone in preventing spinal bone loss over a period of 2 years. However, the presence of other trace elements in the supplement makes it impossible to determine whether manganese supplementation was the beneficial agent for maintaining bone mineral density.

Diabetes mellitus

Manganese deficiency results in glucose intolerance similar to diabetes mellitus in some animal species, but studies examining the manganese status of diabetic humans have generated mixed results. Whole blood manganese levels did not differ significantly between 57 diabetics and 28 non-diabetic controls. However, urinary manganese excretion tended to be slightly higher in 185 diabetics compared to 185 non-diabetic controls. Additionally, a study of functional manganese status found the activity of the antioxidant enzyme, MnSOD, to be lower in the white blood cells of diabetics than in those of non-diabetic controls . Neither 15 mg nor 30 mg of oral manganese improved glucose tolerance in diabetics or non-diabetic controls when given at the same time as an oral glucose challenge. Although manganese appears to play a role in glucose metabolism, there is little evidence that manganese supplementation improves glucose tolerance in diabetic or non-diabetic individuals.

Epilepsy (seizure disorders)

Manganese deficient rats are more susceptible to seizures, and rats that are genetically prone to epilepsy have lower than normal brain and blood manganese levels. Certain subgroups of humans with epilepsy have been found to have lower whole blood manganese levels than non-epileptic controls. One study found blood manganese levels of individuals with epilepsy of unknown origin to be lower than those of individuals whose epilepsy was induced by trauma (e.g., head injury) or disease, suggesting a possible genetic relationship between epilepsy and abnormal manganese metabolism. While manganese deficiency does not appear to be a cause of epilepsy in humans, the relationship between manganese metabolism and epilepsy deserves further research.

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