Manganese (Mn) is a mineral necessary in very tiny (trace) amounts for human health. In large quantities, manganese is poisonous. Manganese is used in some enzyme reactions and for the proper development of bones and cartilage. Humans must meet their needs for manganese from their diet. Manganese is

Manganese

Age	Recommended Dietary Allowance (mg)	Tolerable Upper Intake Level (mg)
Children 0–6 mos.	0.3 (AI)	Not established
Children 7–12 mos.	0.6 (AI)	Not established
Children 1–3 yrs.	1.2	2
Children 4–8 yrs.	1.5	3
Boys 9–13 yrs.	1.9	6
Girls 9–13 yrs.	1.6	6
Boys 14–18 yrs.	2.2	9
Girls 14–18 yrs.	1.6	9
Men 19≤ yrs.	2.3	11
Women 19≤ yrs.	1.8	11
Pregnant women	2.0	11
Breastfeeding women	2.6	11

Food	Manganese (mg)
Tea, green, 1 cup	1.58
Pineapple, raw, ½ cup	1.28
Pecans, 1 oz.	1.12
Cereal, raisin bran, ½ cup	.94
Brown rice, cooked, ½ cup	.88
Spinach, cooked, ½ cup	.84
Tea, black, 1 cup	.77
Almonds, 1 oz.	.74
Bread, whole wheat, 1 slice	.65
Peanuts, 1 oz.	.59
Sweet potato, mashed, ½ cup	.55
Beans, navy, cooked, ½ cup	.51
Beans, lima, cooked, ½ cup	.48
Beans, pinto, cooked, ½ cup	.48
AI = Adequate Intake
mg = milligram

(Illustration by GGS Information Services/Thomson Gale.)

found mainly in plants and in small quantities in some drinking water.

Purpose

Researchers understand less about how manganese functions in the body than they do about many other minerals. Studies have shown that manganese is necessary for proper development of healthy bones and cartilage in animals. It is highly likely that manganese plays the same role in the development of human bones and connective tissue, although manganese deficiency is so rare in humans (and putting people on a prolonged manganese-free diet would be an unethical experiment) that this has not been proven experimentally.

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 manganese 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 manganese excess are rare. The few cases of dietary manganese excess that have been recorded have resulted from accidental exposure such as from drinking water contaminated with manganese-containing industrial waste. The United States Environmental Protection Agency (EPA) recommends a concentration of manganese 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 values called Dietary Reference Intakes (DRIs) for many vitamins and 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 determinean 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, and breastfeeding women.

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 established; All manganese should come from food.
children 7–12 months: AI 0.6 mg; UL not established; 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 mg

Sources 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. Therefore brown rice is a good source of manganese, but white rice is not. Whole wheat flour has more manganese 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 contain glucosamine and chrondroitin may also contain manganese. The best way to get an adequate amount of manganese

KEY TERMS

Alternative medicine—A system of healing that rejects conventional, pharmaceutical-based medicine and replaces it with the use of dietary supplements and therapies such as herbs, vitamins, minerals, massage, and cleansing diets. Alternative medicine includes well-established treatment systems such as homeopathy, Traditional Chinese Medicine, and Ayurvedic medicine, as well as more-recent, fad-driven treatments.

Amino acid—Molecules that are the basic building blocks of proteins.

Antioxidant—A molecule that prevents oxidation. In the body antioxidants attach to other molecules called free radicals and prevent the free radicals from causing damage to cell walls, DNA, and other parts of the cell.

Bile—A greenish-yellow digestive fluid produced by the liver and stored in the gall bladder. It is released into the intestine where it helps digest fat, and then is removed from the body in feces.

Conventional medicine—Mainstream or Western pharmaceutical-based medicine practiced by medical doctors, doctors of osteopathy, and other licensed health care professionals.

Dietary supplement—A product, such as a vitamin, mineral, herb, amino acid, or enzyme, that is intended to be consumed in addition to an individual’s diet with the expectation that it will improve health.

Enzyme—A protein that change the rate of a chemical reaction within the body without themselves being used up in the reaction.

Free radical—A molecule with an unpaired electron that has a strong tendency to react with other molecules in DNA (genetic material), proteins, and lipids (fats), resulting in damage to cells. Free radicals are neutralized by antioxidants.

Glucose—A simple sugar that results from the breakdown of carbohydrates. Glucose circulates in the blood and is the main source of energy for the body.

Homeostasis—The complex set of regulatory mechanisms that works to keep the body at optimal physiological and chemical stability in order for cellular reactions to occur.

Hormone—A chemical messenger that is produced by one type of cell and travels through the bloodstream to change the metabolism of a different type of cell.

Mineral—An inorganic substance found in the earth that is necessary in small quantities for the body to maintain a health. Examples: zinc, copper, iron.

Osteoporosis—A condition found in older individuals in which bones decrease in density and become fragile and more likely to break. It can be caused by lack of vitamin D and/or calcium in the diet.

Serum—The clear fluid part of the blood that remains after clotting. Serum contains no blood cells or clotting proteins, but does contain electrolytes.

is to eat a healthy diet high in green vegetables and whole grains.

The following list gives the approximate manganese content for some common foods:

raisin bran cereal, ½ cup: 0.94 mg
brown rice, cooked, ½ cup: 0.88 mg
pinto beans, cooked, ½ cup: 0.48 mg
lima beans, cooked, ½ cup: 0.48 mg
navy beans, cooked, ½ cup: 0.51 mg
whole wheat bread, 1 slice: 0.65 mg
pineapple, raw, ½ cup: 1.28 mg
pecans, 1ounce: 1.12mg
almonds, 1 ounce: 0.74 mg
peanuts, 1 ounce: 0.59 mg
spinach, cooked, ½ cup: 0.84 mg
sweet potato, mashed, ½ cup: 0.55 mg
tea, green, 1 cup (8 ounces): 0.40-1.58 mg
tea, black, 1 cup (8 ounces): 0.18-0.77 mg

Controversial health claims for manganese

Manganese supplements have not been proven effective in treating or preventing any specific disease or condition. However, based on a small number of laboratory and animal studies, practitioners of alternative medicine sometimes recommend supplemental manganese for the following conditions. These uses are considered speculative by practitioners of conventional medicine.

prevention of osteoporosis
treatment of rheumatoid arthritis
treatment of premenstrual symptoms

seizure prevention in individuals with epilepsy
control of glucose levels in people with diabetes

Precautions

Liver damage may reduce the rate at which magnesium is removed from the body. People with liver damage (e.g. cirrhosis) may be at higher risk of developing symptoms of manganese excess.

Interactions

Antacids and laxatives that contain magnesium (e.g. milk of magnesia) may reduce the amount of manganese absorbed from food.

Complications

No complications are expected from manganese acquired through food and water. Individuals who take multivitamin/mineral supplements containing manganese are unlikely to have any adverse effects. People who take manganese or joint supplements should be alert to how much manganese they are consuming, although overdose is extremely rare.

Parental concerns

Parents should have few concerns about children getting either too much or too little manganese. Supplemental manganese should rarely be necessary. Parents should encourage their children to eat a diet high in fruits, vegetables, and whole grains.

Resources

BOOKS

Fragakis, Allison. The Health Professional’s Guide to Popular Dietary Supplements.Chicago: American Dietetic Association, 2003

Lieberman, Shari and Nancy Bruning. The Real Vitamin and Mineral Book: The Definitive Guide to Designing Your Personal Supplement Program,4th ed. New York: Avery, 2007.

Pressman, Alan H. and Sheila Buff. The Complete Idiot’s Guide to Vitamins and Minerals, 3rd ed. Indianapolis, IN: Alpha Books, 2007.

ORGANIZATIONS

Linus Pauling Institute. Oregon State University, 571 Weniger Hall, Corvallis, OR 97331-6512. Telephone: (541) 717-5075. Fax: (541) 737-5077. Website: <http://lpi.oregonstate.edu>

Office of Dietary Supplements, National Institutes of Health. 6100 Executive Blvd., Room 3B01, MSC 7517, Bethesda, MD 20892-7517 Telephone: (301)435-2920. Fax: (301)480-1845. Website: <http://dietary-supplements.info.nih.gov>

OTHER

Familydoctor.org. “Vitamins and Minerals: What You Should Know.” American Family Physician, December 2006. <http://familydoctor.org/>

Higdon, Jane. “Manganese.” Linus Pauling Institute-Oregon State University, August 8, 2001. <http://lpi.oregonstate.edu/infocenter/minerals/manganese>

Maryland Medical Center Programs Center for Integrative Medicine. “Manganese.” University of Maryland Medical Center, April 2002. <http://www.umm.edu/altmed/ConsSupplements/manganesecs>

Mayo Clinic Staff. “Dietary Supplements: Using Vitamin and Mineral Supplements Wisely.” MayoClinic.com, June 5, 2006. <http://www.mayoclinic.com/health/supplements/NU00198>

Helen M. Davidson