Manganese Overview

Our bodies contain only a very small amount of manganese, but this metal is important as a constituent of many key enzymes. The chemical structure of these enzymes is interesting: large protein molecules cluster around a tiny atom of metal.

Manganese plays a particularly important role as part of the natural antioxidant enzyme superoxide dismutase (SOD), which helps fight damaging free radicals. It also helps energy metabolism, thyroid function, blood sugar control, and normal skeletal growth.

The official US recommendations for daily intake of manganese are as follows:

• Infants

• 0-6 months: 0.003 mg

• 7-12 months: 0.6 mg

• Children

• 1-3 years: 1.2 mg

• 4-8 years: 1.5 mg

• Males

• 9-13 years: 1.9 mg

• 14-18 years: 2.2 mg

• 19 years and older: 2.3 mg

• Females

• 9-18 years: 1.6 mg

• 19 years and older: 1.8 mg

• Pregnant women: 2 mg

• Nursing women: 2.6 mg

The absorption of manganese may be impaired by simultaneous intake of antacids or calcium or iron supplements. ^{1 2} The best sources of dietary manganese are whole grains, legumes, avocados, grape juice, chocolate, seaweed, egg yolks, nuts, seeds, boysenberries, blueberries, pineapples, spinach, collard greens, peas, and green vegetables.

A typical dosage used in studies on manganese is 3 to 6 mg daily. It is sometimes recommended at a much higher dose of 50 to 200 mg daily for 2 weeks following a muscle sprain or strain, but this dosage exceeds recommended safe intake levels (see Safety Issues).

Osteoporosis

Although manganese is known to play a role in bone metabolism, there is no direct evidence that manganese supplements can help prevent osteoporosis . However, one double-blind placebo-controlled study suggests that a combination of minerals including manganese may be helpful. ³ Fifty-nine women took either placebo, calcium (1,000 mg daily), or calcium plus a daily mineral supplement consisting of 5 mg of manganese, 15 mg of zinc, and 2.5 mg of copper. After 2 years, the group receiving calcium plus minerals showed better bone density than the group receiving calcium alone. But this study doesn't tell us whether it was the manganese or the other minerals that made the difference.

Dysmenorrhea (Menstrual Pain)

One very small, but well-designed and carefully conducted double-blind study suggested that 5.6 mg of manganese daily might ease menstrual discomfort . ⁴ In the same study, a lower dosage of 1 mg daily wasn'teffective.

1. Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington DC: National Academy of Sciences; 2001.
2. Davidsson L, Cederblad A, Lönnerdal B, Sandström B. The effect of individual dietary components on manganese absorption in humans. Am J Clin Nutr. 54(6):1065-70.
3. Strause L, Saltman P, Smith KT, Bracker M, Andon MB. Spinal bone loss in postmenopausal women supplemented with calcium and trace minerals. J Nutr. 124(7):1060-4.
4. Penland JG, Johnson PE. Dietary calcium and manganese effects on menstrual cycle symptoms. Am J Obstet Gynecol. 168(5):1417-23.