Manganese is a trace element that is needed in the body and a healthy adult will have around 12 – 20 mg of it in their body 1. It is needed for healthy bone development as well as in the production of the hormone thyroxine.
Manganese is absorbed as Mn 2+ ions. Deficiencies of it in the diet are rare but may manifest themselves in conditions such as poor bone development or the slowed growth of hair and nails. A good source of manganese comes from eating green leafy vegetables as it is involved in photosynthesis.
By Sterilgutassistentin (Own work) [GPL (http://www.gnu.org/licenses/gpl.html)], via Wikimedia Commons