Manganese

What Is Manganese?

Manganese is a metal the body needs only in traces: an adult holds roughly 10 to 20 mg in total, a good part of it in bone. Its value lies in the enzymes it activates, not in any structure it builds.

Enzymes That Need Manganese

Manganese superoxide dismutase (MnSOD) sits inside mitochondria, where cells burn fuel, and neutralizes the superoxide those reactions give off. Arginase, another manganese enzyme, works in the liver's urea cycle, which turns the nitrogen from protein into urea for the kidneys to remove. Pyruvate carboxylase helps the liver make glucose between meals.

Manganese also activates the enzymes that build proteoglycans, the cushioning molecules of cartilage and bone, and it plays a part in blood clotting with vitamin K. Clear deficiency is almost never seen in people eating ordinary food.

How the Body Absorbs and Clears Manganese

Less than 5% of the manganese in food is absorbed. The liver then sends the excess into bile, and it leaves with stool. Absorption is tied to iron: the two share a transport route in the gut, so people with low iron stores absorb more manganese and people with high iron intake absorb less.

That reliance on bile is why liver disease matters here. When the liver cannot clear it, manganese can build up in the brain, even from ordinary food.

Manganese per Portion in Common Foods

Manganese in a usual portion of the richest foods with a Caltide calorie page, to one decimal.

A cup of pineapple gives more than a tablespoon of chia seeds, even though chia has about nine times as much per 100 g.

Other Rich Sources of Manganese

Mussels, hazelnuts, pecans, brown rice, oatmeal, chickpeas and black tea are rich sources too. Tea matters for heavy drinkers, since a few cups a day add up. Whole grains carry far more than refined ones, because manganese sits in the bran and germ that milling removes.

When Manganese Becomes Harmful

Manganese from food is rarely harmful. The well-documented harm is from breathing it: welders, miners and workers in steel and battery plants who inhale manganese dust or fumes can develop manganism, a nerve disorder with tremor and stiff movement much like Parkinson's disease. Inhaled manganese skips the gut and the liver, which normally limit how much reaches the brain.

Other groups at risk of too much are people with chronic liver disease, people fed long term by vein (parenteral nutrition), and people, especially infants, who drink well water high in manganese.