Nutrients – Manganese

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.