:Manganese:

:Manganese is essential for healthy skin, bone, and cartilage formation, as well as glucose tolerance. Manganese participates in superoxide dismutase (SOD), one of the most important antioxidant enzymes.

In plants, the splitting of water by sunlight, occurs at a catalytic centre that consists of four manganese atoms. Three of the manganese atoms, a calcium atom and four oxygen atoms form a cube-like structure, which brings stability to the catalytic centre. The fourth and most reactive manganese atom is attached to one of the oxygen atoms of the cube.

Sources:

Nuts and seeds, wheat germ, wheat bran, leafy green vegetables, beet tops, tea and pineapple.

Uses:

• Tardive dyskinesia
• Diabetes
• Hypoglycemia
• Osgood-Schlatter disease
• Osteoporosis
• Sprains and strains

Deficiency:

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. 2The 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.

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 intravenously 3 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.

Calcium, iron and possibly zinc reduce absorption of manganese. 10 The link to iron may be most important: Women with high iron have relatively poor absorption of manganese. 11 High intake of non-heme iron, as in most supplements, decreases manganese status. 12 Taking multi-minerals with manganese may protect against manganese deficiencies that might otherwise be triggered by taking iron.

Certain medications may interact with manganese.

• Ciprofloxacin (Reduced drug absorption/bioavailability)
• Oral Contraceptives may interfere with manganese absorption.

References:

1. Raloff J. Reasons for boning up on manganese. Science 1986;130:199 [review].
2. National Research Council. Recommended Dietary Allowance s. 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.