Minute quantities of manganese are also needed for protein and fat metabolism, and blood sugar regulation.
Body contains between 10 to 20 milligrams of manganese, which is concentrated primarily in the bone, liver, pancreas and brain. Rich sources of manganese include: whole grains, clams, oysters, mussels, nuts, soybeans and other legumes, rice, leafy vegetables, coffee, tea, and many spices, such as black pepper.
The highest concentrations are found in certain foods of plant origin, especially wheat and rice, with concentrations between 10 mg/kg and 100 mg/kg. Polished rice and wheat flour contain less manganese, because most of it is in the bran. High concentrations of manganese have been found in tea leaves.
Drinking water also contains small amounts of manganese at concentrations of 1 to 100 mcg/L. although drinking-water generally contains less than 100 µg/liter. The top sources of manganese in the diets of U.S. adults are grain products, tea, and vegetables.
Manganese is available in many multivitamin/multimineral and other dietary supplements. Supplements contain many forms of manganese, such as manganese sulfate and manganese aspartate.
In the United States, estimated average intakes of dietary manganese range from 2.1 to 2.3 mg/day for men and 1.6 to 1.8 mg/day for women. Surveys have found those adhering to vegetarian diet have manganese intakes of up to 7.0 mg/day.
Absorption of manganese is poor, only 1 to 15 percent. The high levels of iron, calcium and phosphorus may inhibit absorption.
Manganese is absorbed in the small intestine through an active transport system and, possibly, through diffusion when intakes are high. After absorption, some manganese remains free, but most is bound to transferrin, albumin, and plasma alpha-2 macroglobulin.
Food sources of manganese
