radicals are molecules that cause damage by reacting
withfatsand proteins in cell membranes and in genetic
material. This process is called oxidation.Antioxi-
dantsare compounds that attach themselves to free
radicals so that it is impossible for free radicals to react
with, or oxidize, other molecules. In this way, antiox-
idants protect cells from damage. Although manga-
nese is not by itself an antioxidant, it is a necessary
part of the enzyme reaction that neutralizes free radi-
cals produced by mitochondria. Manganese is also
needed in some enzyme reactions that allow the body
to process the use of amino acids, cholesterol, and
carbohydratesin the body.
Description
Manganese is acquired through diet. It is not
evenly distributed in the body but is concentrated in
the bones, liver, pancreas, and brain. Excess manga-
nese is removed in bile, a digestive fluid made by the
liver. The role of manganese in health is not well
understood. Both manganese deficiency and manga-
nese excess are rare. The few cases of dietary manga-
nese excess that have been recorded have resulted from
accidental exposure such as from drinking water con-
taminated with manganese-containing industrial
waste. The United States Environmental Protection
Agency (EPA) recommends a concentration of man-
ganese no higher than .05 mg/L in drinking water.
Side effects of high levels of manganese include loss
of appetite, headaches, tremors, convulsions, and
mental changes such a hallucinations. If manganese
is inhaled in dust or vapor, it can cause severe damage
to the nervous system. Some miners and industrial
workers are at risk of being exposed to airborne
manganese.
Normal manganese requirements
The United States Institute of Medicine (IOM) of
the National Academy of Sciences has developed val-
ues calledDietary Reference Intakes(DRIs) for many
vitaminsand minerals. The DRIs consist of three sets
of numbers. The Recommended Dietary Allowance
(RDA) defines the average daily amount of the
nutrient needed to meet the health needs of 97–98%
of the population. The Adequate Intake (AI) is an
estimate set when there is not enough information to
determine an RDA. The Tolerable Upper Intake Level
(UL) is the average maximum amount that can be
taken daily without risking negative side effects. The
DRIs are calculated for children, adult men, adult
women, pregnant women, andbreastfeedingwomen.
The IOM has not set RDAs for manganese
because not enough information is available about
the need for manganese in humans. Instead, it has set
AI levels for all age groups. Because high levels of
manganese affect the nervous system, the ULs are
very conservative. Some experts point out that vegans
and vegetarians who eat large quantities of whole
grains routinely take in manganese in amounts well
above the established UL without any obvious adverse
effects. IAs and ULs for manganese are measured in
milligrams (mg).
The following list gives the daily IAs and ULs for
manganese for healthy individuals as established by
the IOM.
children birth–6 months: AI 0.3 mg; UL not estab-
lished; All manganese should come from food.
children 7–12 months: AI 0.6 mg; UL not estab-
lished; All manganese should come from food.
children 1–3 years: RDA 1.2 mg; UL 2 mg
children 4–8 years: RDA 1.5 mg; UL 3 mg
boys 9–13 years: RDA 1.9 mg; UL 6 mg
girls 9–13 years: RDA 1.6 mg; UL 6 mg
boys 14–18 years: RDA 2.2 mg; UL 9 mg
girls 14–18 years: RDA 1.6 mg; UL 9 mg
children 4–8 years: RDA 1.5 mg; UL 3 mg
boys 9–13 years: RDA 1.9 mg; UL 6 mg
girls 9–13 years: RDA 1.6 mg; UL 6 mg
boys 14–18 years: RDA 2.2 mg; UL 9 mg
girls 14–18 years: RDA 1.6 mg; UL 9 mg
men age 19 and older: RDA 2.3 mg; UL 11 mg
women age 19 and older: RDA 1.8 mg; UL 11 mg
pregnant women of all ages: RDA 2.0 mg; UL 11 mg
breastfeeding women of all ages: RDA 2.6 mg;
UL 11 mgSources of manganese
Almost all people get enough manganese from
their normal diet. Good sources of manganese include
nuts, seeds, whole grains, leafy green vegetables, and
tea. Some water that is high in minerals (‘‘hard’’ water)
may contain small amounts of manganese; the amount
varies depending on location. Whole grains contain
manganese, but processing removes most of it. There-
fore brown rice is a good source of manganese, but
white rice is not. Whole wheat flour has more manga-
nese than white flour, and wheat bran has more than
either type of flour. Manganese is also found in multi-
vitamin/mineral supplements, and in single-ingredient
supplements. Joint supplements that containglucos-
amineand chrondroitin may also contain manganese.
The best way to get an adequate amount of manganeseManganese