Manganese is an essential dietary element that functions primarily as a coenzyme in several biological processes. These processes include, but are not limited to, macronutrient metabolism, bone formation, free radical defense systems, and in the brain, ammonia clearance and neurotransmitter synthesis. It is a critical component in dozens of proteins and enzymes, and it is found in all tissues. Concentrated levels of Mn are found in tissues rich in mitochondria and melanin, with both the liver and pancreas having the highest concentrations under normal conditions. However, overexposure to environmental Mn via industrial occupation or contaminated drinking water can lead to toxic brain Mn accumulation that has been associated with neurological impairment.
Erikson KM, Aschner M. Manganese: Its Role in Disease and Health. Met Ions Life Sci. 2019 Jan 14;19:/books/9783110527872/9783110527872-016/9783110527872-016.xml. doi: 10.1515/9783110527872-016. PMID: 30855111.