Manganese

What does it do? Manganese is needed for healthy skin, bone, and cartilage formation, as well as glucose tolerance. It also helps activate superoxide dismutase (SOD)—an important antioxidant enzyme.

Where is it found? Nuts and seeds, wheat germ, wheat bran, leafy green vegetables, beet tops, tea, and pineapple are all good sources of manganese.

Manganese has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
2Stars Tardive dyskinesia
1Star Diabetes
Hypoglycemia
Osgood-Schlatter disease
Osteoporosis
Sprains and strains
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? Many people consume less than the 2–5 mg of manganese currently considered safe and adequate. Nonetheless, clear deficiencies are rare. People with osteoporosis sometimes have low blood levels of manganese, suggestive of deficiency.1

How much is usually taken? Whether most people would benefit from manganese supplementation remains unclear. While there is no recommended dietary allowance, the National Research Council’s “estimated safe and adequate daily dietary intake” is 2–5 mg.2 The Institute of Medicine recommends that intake of manganese from food, water and dietary supplements should not exceed the tolerable daily upper limit of 11 mg per day. In contrast, the 5–15 mg often found in high-potency multivitamin-mineral supplements is generally considered to be a reasonable level by many doctors, though many manufacturers are likely to reformulate their products to contain no more than 11 mg per daily amount.

Are there any side effects or interactions? Amounts found in supplements (5–20 mg) have not been linked with any toxicity. Excessive intake of manganese rarely lead to psychiatric symptoms. However, most reports of manganese toxicity in otherwise healthy people have been in those people who chronically inhaled manganese dust at their jobs e.g., miners or alloy plant workers. Other sources of manganese intoxication are now recognized, including total parenteral nutrition (TPN) in patients who are being fed intravenously3 4 5 and pesticides containing manganese in agricultural workers who have been exposed.6

Preliminary research suggests that people with cirrhosis 7 or cholestasis (blocked bile flow from the gall bladder)8 may not be able to properly excrete manganese. Until more is known, these people should not supplement manganese. Manganese supplementation (3–5 mg per day) has caused severe hypoglycemia (low blood sugar) in a person with insulin-dependent diabetes.9 People with diabetes who want to take manganese should consult their doctor.

Several minerals, such as calcium and iron, and possibly zinc, reduce the absorption of manganese.10 Of these interactions, the link to iron may be the most important. In one study, women with high iron status had relatively poor absorption of manganese.11 In another report of manganese/iron interactions in women, increased intake of “non-heme iron”—the kind of iron found in most supplements—decreased manganese status.12 These interactions suggest that taking multi-minerals that include manganese may protect against manganese deficiencies that might otherwise be triggered by taking isolated mineral supplements, particularly iron.

Are there any drug interactions? Certain medications may interact with manganese. Refer to the drug interactions safety check for a list of those medications.

References:

1. Raloff J. Reasons for boning up on manganese. Science 1986;130:199 [review].

2. National Research Council. Recommended Dietary Allowances. 10th ed. Washington, DC: National Academy Press, 1989.

3. Nagatomo S, Umehara F, Hanada K, et al. Manganese intoxication during total parenteral nutrition: report of two cases and review of the literature. J Neurol Sci 1999;162:102–5.

4. Ejima A, Imamura T, Nakamura S, et al. Manganese intoxication during total parenteral nutrition. Lancet 1992;339:426 [letter].

5. Fell JM, Reynolds AP, Meadows N, et al. Manganese toxicity in children receiving long-term parenteral nutrition. Lancet 1996;347:1218–21.

6. Ferraz HB, Bertolucci PH, Pereira JS, et al. Chronic exposure to the fungicide maneb may produce symptoms and signs of CNS manganese intoxication. Neurology 1988;38:550–3.

7. Krieger D, Krieger S, Jansen O, et al. Manganese and chronic hepatic encephalopathy. Lancet 1995;346:270–4.

8. Staunton M, Phelan DM. Manganese toxicity in a patient with cholestasis receiving total parenteral nutrition. Anaesthesia 1995;50:665.

9. Rubenstein AH, Levin NW, Elliott GA. Hypoglycaemia induced by manganese. Nature (London) 1962;194:188–9.

10. Freeland-Graves JH. Manganese: an essential nutrient for humans. Nutr Today 1989;23:13–9 [review].

11. Finley JW. Manganese absorption and retention by young women is associated with serum ferritin concentration. Am J Clin Nutr 1999;70:37–43.

12. Davis CD, Malecki EA, Gerger JL. Interactions among dietary manganese, heme iron, and nonheme iron in women. Am J Clin Nutr 1992;56:926–32.