Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver a scientific opinion on Dietary Reference Values for the European population, including manganese.
In 1993, the Scientific Committee for Food set an Acceptable Range of Intakes for adults at 1–10 mg/day, considering observed intakes of manganese in European countries and data from balance studies. A few other authorities have set Adequate Intakes (AIs) for manganese, based on similar considerations.
Manganese is an essential dietary element for mammals. It is a component of metalloenzymes such as superoxide dismutase, arginase and pyruvate carboxylase, and is involved in amino acid, lipid and carbohydrate metabolism. A specific manganese deficiency syndrome has not been described in humans.
Absorption of manganese in the intestine is low (< 10 %). Regulation at the level of absorption appears to be one of the adaptive responses to dietary manganese intake and such regulation allows manganese homeostasis to be maintained over a wide range of intakes. A reduction in the biological half-life of manganese has been observed with increased dietary manganese intakes indicating the role of whole-body turnover rate in manganese homeostasis. Elimination of manganese is primarily via the faeces.
The assessment of manganese intake or status using biological markers is difficult owing to the rapid excretion of manganese into bile, to homeostatic mechanisms and to the lack of sensitivity of biomarkers over the normal range of intakes. Therefore, there are no reliable and validated biomarkers of manganese intake or status.
Nuts, chocolate, cereal-based products, crustaceans and molluscs, pulses, and fruits and fruit products are rich sources of manganese. The main contributors to the manganese intake of adults are cereal-based products, vegetables, fruits and fruit products and beverages. In the EU, estimated mean manganese intakes of adults range from 2 to 6 mg/day, with a majority of values around 3 mg/day. Estimated mean manganese intakes range from 1.5 to 3.5 mg/day in children, and from 2 to 6 mg/day in adolescents.
Several balance studies have been undertaken to establish manganese requirements. These studies demonstrate that the body adapts quickly to changes in manganese intake. Although balance may be maintained at intakes below 2.5 mg/day, null or positive balances have consistently been observed with manganese intakes above 2.5 mg/day.Manganese balance may be influenced by the overall diet, variations in individual rates of absorption or excretion, differences in body contents and adaptation to varying dietary levels, which make comparisons between subjects and studies difficult.
No data on manganese intakes and health outcomes were identified for the setting of DRVs.
As the evidence to derive an Average Requirement and thus a Population Reference Intake is considered insufficient, an Adequate Intake (AI) is proposed. Observed mean intakes of adults in the EU are typically around 3 mg/day. In addition, null or positive balances have consistently been observed with intakes of manganese above 2.5 mg/day. An AI of 3 mg/day for adults is, therefore, proposed. The adult AI also applies to pregnant and lactating women. For infants aged from 7 to 11 months, the Panel decides to set a range for the AI of 0.02–0.5 mg/day. This reflects the wide range of manganese intakes that appear to be adequate, based on upwards extrapolation of manganese intakes in fully breast-fed infants, observed intake of manganese in infants aged 6 and 12 months and the value estimated from extrapolation of the adult AI using isometric scaling. For children and adolescents, an AI is proposed based on extrapolation from the adult AI using isometric scaling (i.e. extrapolation based on reference body weights of the respective age groups) and rounding to the nearest 0.5. The respective AIs vary from 0.5 mg/day in young children aged 1–3 years to 3.0 mg/day in adolescent boys and girls.