Manganese
Overview
Manganese is a trace mineral that is
present in tiny amounts in the body. It is found mostly in bones,
the liver, kidneys, and pancreas. Manganese helps the body form
connective tissue, bones, blood clotting factors, and sex hormones.
It also plays a role in fat and carbohydrate metabolism, calcium
absorption, and blood sugar regulation. Manganese is also necessary
for normal brain and nerve function.
Manganese is a component of the
antioxidant enzyme superoxide dismutase (SOD), which helps fight free
radicals. Free radicals occur naturally in the body but can damage
cell membranes and DNA. They may play a role in aging, as well as
the development of a number of health conditions, including heart
disease and cancer. Antioxidants, such as SOD, can help neutralize
free radicals and reduce or even help prevent some of the damage they
cause.
Low levels of manganese in the body can
contribute to infertility, bone malformation, weakness, and seizures.
It is fairly easy to get enough manganese in your diet -- this
nutrient is found in whole grains, nuts, and seeds -- but some
experts estimate that as many as 37% of Americans do not get the
recommended dietary intake (RDI) of manganese in their diet. The
American diet tends to contain more refined grains than whole grains,
and refined grains only provide half the amount of manganese as whole
grains.
Deficiency Symptoms
1. Asthma – Low manganese levels are consistently associated
with childhood asthma, while one study found a similar relationship
between dietary manganese intake and asthma in adults.
2. Ineffective utilization of several key nutrients –
Choline, thiamin, ascorbic acid, and biotin all require adequate
manganese to be utilized by the body.
3. Low thyroxine (thyroid hormone T4) – Manganese is
essential in the production of T4.
4. Osteoporosis and joint pain - Bone mineral density doesn’t
just come down to calcium (or magnesium). Manganese also plays a
small but important role in skeletal health. Consider the story of
Bill Walton, basketball legend and the greatest hyperbolist in the
history of Western Civilization, who was diagnosed with osteoporosis
at the height of his career after a series of broken bones that would
not heal. The cause? A macrobiotic diet that left his serum
manganese levels entirely undetectable.
5. Low HDL – In women fed a manganese-deficient diet, HDL
plummeted.
Tests
Trace mineral testing is usually
performed on a blood sample. Sometimes a 24-hour urine collection is
obtained. Special metal-free blood or acid-washed urine containers
are used to minimize the potential for sample contamination by any
outside sources of minerals.
Blood and urine reflect recent mineral
intake. Rarely, hair may be collected or a biopsy may be performed
to obtain a tissue sample to evaluate mineral deficiencies, excesses,
and storage that have occurred over time.
Recommended Daily Allowance
The daily Adequate Intake (AI) for
manganese is listed below. Supplements and dietary intake of
manganese together should not exceed 10 milligrams per day because of
the risk of nervous system side effects. You should only take
manganese supplements under the supervision of your doctor; that is
especially true for children.
Children and Infants
Infants 0 - 6 months: 0.003 mg
Infants 7 months - 1 year: 0.6
mg
Children 1 - 3 years: 1.2 mg
Children 4 - 8 years: 1.5 mg
Males 9 - 13 years: 1.9 mg
Males 14 - 18 years: 2.2 mg
Females 9 - 18 years: 1.6 mg
Adult
Males 19 years and older: 2.3
mg
Females 19 years and older: 1.8
mg
Pregnant women: 2 mg
Breastfeeding women: 2.6 mg
Pregnant women and nursing mothers
should avoid intakes of manganese above the upper limit of the AI,
unless under a doctor's supervision.
Function
Diabetes is a possible problem
associated with manganese. Some studies show that people with
diabetes have low levels of manganese in their blood. Researchers
don't know if having diabetes causes levels to drop, or whether low
levels of manganese contribute to developing diabetes. It should be
a priority that more studies are needed. One clinical study found
that people with diabetes who had higher blood levels of manganese
were more protected from LDL or "bad" cholesterol than
those with lower levels of manganese.
Food Sources
The following are important sources of
manganese. In descending order from richest, hazelnuts, pine nuts,
pecans, walnuts, mac nuts, and almonds are all good sources of
manganese. Bivalves from the sea and mussels are the best source,
followed by oysters and clams. Raspberries and dark chocolate when
eaten together can also be an excellent source. Other dietary
sources of manganese include wheat germ and whole grains (including
unrefined cereals, buckwheat, bulgur wheat, and oats), legumes, and
pineapples.
Precautions Toxicity
Inhaled manganese
Manganese toxicity can result in
multiple neurological problems and is a well-recognized health hazard
for people who inhale manganese dust, such as welders and smelters.
Unlike ingested manganese, inhaled manganese is transported directly
to the brain before it can be metabolized in the liver. The symptoms
of manganese toxicity generally appear slowly over a period of months
to years. In its worst form, manganese toxicity can result in a
permanent neurological disorder with symptoms similar to those of
Parkinson's disease, including tremors, difficulty walking, and
facial muscle spasms. This syndrome, often called manganism, is
sometimes preceded by psychiatric symptoms, such as irritability,
aggressiveness, and even hallucinations. Environmental or
occupational inhalation of manganese can cause an inflammatory
response in the lungs. Clinical symptoms of effects to the lung
include cough, acute bronchitis, and decreased lung function.
Methylcyclopentadienyl manganese
tricarbonyl (MMT)
MMT is a manganese-containing compound
used in gasoline as an anti-knock additive. Although it has been used
for this purpose in Canada for more than 20 years, uncertainty about
adverse health effects from inhaled exhaust emissions kept the US
environmental protection agency (EPA) from approving its use in
unleaded gasoline. In 1995, a U.S. court decision made MMT available
for widespread use in unleaded gasoline. A study in Montreal, where
MMT had been used for more than ten years, found airborne manganese
levels to be similar to those in areas where MMT was not used. A
more recent Canadian study found higher concentrations of respirable
manganese in an urban versus a rural area, but average concentrations
in both areas were below the safe level set by the U.S. EPA.
Ingested manganese
Limited evidence suggests that high
manganese intakes from drinking water may be associated with
neurological symptoms similar to those of Parkinson's disease.
Severe neurological symptoms were reported in 25 people who drank
water contaminated with manganese. Manganese in drinking water may
be more bioavailable than manganese in food. Additionally, studies
that are more recent have shown that children exposed to high levels
of manganese through drinking water experience cognitive and
behavioral deficits. Manganese toxicity resulting from foods alone
has not been reported in humans, even though certain vegetarian diets
could provide up to 20 mg/day of manganese.
Possible Interactions
If you are currently being treated with
any of the following medications, you should not use manganese
supplements without first talking to your health care provider.
1. Haloperidol and other antipsychotics -- There has been at
least one clinical report of an interaction between haloperidol and
manganese that resulted in hallucinations and behavioral changes in a
person with liver disease. In addition, some experts believe that
medications for schizophrenia and other forms of psychosis may worsen
side effects from manganese supplements. If you take antipsychotic
medications, do not take manganese without first talking to your
doctor.
2. Reserpine -- Reserpine, a medication used to treat high
blood pressure, may lower manganese levels in the body.
3. Antacids -- Magnesium containing antacids may decrease the
absorption of manganese if taken together. Take supplements
containing manganese at least 1 hour before or 2 hours after taking
antacids.
4. Laxatives -- Magnesium containing laxatives may decrease
the absorption of manganese if taken together. Take supplements
containing manganese at least 1 hour before or 2 hours after taking
laxatives.
5. Tetracycline antibiotics -- These drugs may reduce the
absorption of manganese if taken together. Take supplements
containing manganese at least 1 hour before or 2 hours after taking
these antibiotics. They include tetracycline, minocycline (Minocin),
and demeclocycline (Declomycin).
6. Quinolone Antibiotics -- Manganese may inhibit the body's
absorption of these medications.
