Food sources of manganese
The daily requirement for manganese in man is c. 3 mg and the Mn content of current multi-mineral
supplements is probably slightly in excess of requirements. The average UK dietary intake of Mn is 8.2
mg/day and the estimated upper limit is 12.2 mg/day. Manganese is present in many foods, particularly green
vegetables (2 mg/kg), nuts (14.9 mg/kg), bread (8 mg/kg) and other cereals (6.81 mg/kg). Tea is a rich source
of manganese, containing 2.7 mg/kg and is often the largest contributor to manganese intake [8].
Manganese is commonly found in groundwater because of the weathering and leaching of manganesebearing
minerals and rocks into the aquifers; concentrations in drinking water can vary by several orders of
magnitude. In the UK the maximum concentration of manganese permitted in drinking water is 50 µg/L [9]
but the usual level recorded is below 1.0 µg/L. These figures suggest that manganese intake from water is
very small compared to the amount ingested in food.
However, while manganese is widely distributed in unrefined food, excessive reliance on a diet based on
refined grains may result in a deficient intake.