Manganese is involved in the formation of bone and is a component of many enzymes that play important roles in protein, cholesterol and carbohydrate metabolism.
Best Food Sources
Whole grains contribute the most manganese to U.S. diets, followed by tea. One cup of green tea contains about 0.41-1.58 milligrams of manganese and one cup of black tea contains about 0.18-0.77 milligrams. Some fruits and vegetables, including pineapple, beans, spinach and sweet potatoes, are also good sources.
Inadequate Intake and Deficiencies
Since manganese is so widely distributed in the food system, cases of deficiency due to poor dietary intakes have not been reported in humans. In human studies where manganese depletion has been induced, subjects developed skin rashes and abnormally low blood cholesterol levels.
Manganese toxicity from foods has not been reported in humans. Toxic levels of manganese are a well-recognized hazard for people employed in industrial jobs where manganese dust may be inhaled. This can cause nervous-system effects that mimic Parkinson’s disease, including tremors, difficulty walking and facial spasms.