Manganese

Medically reviewed by Prof. Giorgi Pkhakadze, MD, MPH, PhD — GMJ Editorial Board

What is Manganese?

Manganese (Mn) is an essential trace mineral that plays crucial roles in numerous physiological processes throughout the body. Despite being needed in only small amounts, manganese is vital for proper bone development, wound healing, metabolism of amino acids, cholesterol, glucose, and carbohydrates. It also functions as a cofactor for several important enzymes involved in antioxidant defense and energy production.

The body typically contains only 12-20 milligrams of manganese, primarily concentrated in the bones, liver, kidney, and pancreas. Unlike some minerals, the body has limited ability to store manganese, making regular dietary intake important for maintaining optimal levels.

Health benefits & uses

Bone Health (Moderate evidence): Manganese is essential for normal bone formation and maintenance. It serves as a cofactor for enzymes involved in the formation of bone cartilage and bone collagen. Studies suggest adequate manganese intake may help prevent osteoporosis, particularly when combined with other bone-supporting nutrients like calcium, copper, and zinc.

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Antioxidant Function (Strong evidence): Manganese is a critical component of manganese superoxide dismutase (MnSOD), a powerful antioxidant enzyme that protects cells from oxidative damage caused by free radicals. This enzyme is particularly important in protecting mitochondria, the energy-producing structures within cells.

Wound Healing (Moderate evidence): Manganese supports the production of collagen, a protein essential for wound healing and maintaining healthy skin. It also plays a role in blood clotting processes that help stop bleeding from injuries.

Metabolism Support (Strong evidence): The mineral acts as a cofactor for various enzymes involved in carbohydrate, amino acid, and cholesterol metabolism. It’s particularly important for the metabolism of glucose and the synthesis of fatty acids.

Cognitive Function (Limited evidence): Some research suggests manganese may play a role in brain function and neurological health, though more studies are needed to establish clear benefits for cognitive performance.

How it works

Manganese functions primarily as an enzyme cofactor, meaning it helps activate specific enzymes that catalyze important biochemical reactions. Key mechanisms include:

In bone metabolism, manganese activates glycosyltransferases, enzymes that help form proteoglycans necessary for healthy bone matrix formation. For antioxidant protection, it’s an integral part of MnSOD, which converts harmful superoxide radicals into less damaging hydrogen peroxide and oxygen.

In energy metabolism, manganese serves as a cofactor for pyruvate carboxylase, an enzyme crucial for gluconeogenesis (glucose production from non-carbohydrate sources). It also supports the function of arginase, which is involved in the urea cycle for removing toxic ammonia from the body.

The mineral is absorbed in the small intestine, with absorption rates typically ranging from 1-15% depending on dietary intake levels and body stores. The body regulates manganese levels primarily through biliary excretion rather than absorption control.

Dosage

The Recommended Dietary Allowance (RDA) for manganese varies by age and gender:

• Adult men (19+ years): 2.3 mg daily
• Adult women (19+ years): 1.8 mg daily
• Pregnant women: 2.0 mg daily
• Breastfeeding women: 2.6 mg daily

The Tolerable Upper Intake Level (UL) is set at 11 mg daily for adults. Most people can meet their manganese needs through a balanced diet without supplementation. When supplements are used, typical doses range from 1-15 mg daily, though doses should be determined in consultation with a healthcare provider.

Food sources

Manganese is widely distributed in foods, with the richest sources including:

Excellent sources (>1 mg per serving): Whole grains (brown rice, oatmeal, whole wheat bread), nuts (pecans, walnuts, almonds), seeds (pumpkin seeds, sunflower seeds), and legumes (chickpeas, lentils, soybeans).

Good sources (0.5-1 mg per serving): Leafy green vegetables (spinach, kale), tea (both black and green), pineapple, sweet potatoes, and seafood like mussels and clams.

Moderate sources (0.1-0.5 mg per serving): Berries, bananas, carrots, broccoli, and most other fruits and vegetables.

Processing and refining can significantly reduce manganese content, making whole, unprocessed foods the best dietary sources.

Safety & side effects

Manganese from food sources is generally safe, as dietary intake rarely reaches toxic levels. However, excessive intake, particularly from supplements or environmental exposure, can cause manganism, a neurological condition similar to Parkinson’s disease.

Early signs of manganese toxicity may include fatigue, headaches, muscle weakness, and psychiatric symptoms. More severe toxicity can lead to movement disorders, memory problems, and other neurological complications.

Most adverse effects occur with chronic exposure to high levels (>10-20 mg daily over extended periods). Individuals with liver disease may be at higher risk for manganese accumulation since the liver is the primary route for manganese elimination.

Interactions

Mineral interactions: Iron and manganese compete for absorption, so high iron intake may reduce manganese absorption and vice versa. Calcium and magnesium supplements may also interfere with manganese absorption when taken in large amounts.

Medications: Antacids and laxatives containing magnesium may reduce manganese absorption. Some antibiotics, including tetracyclines and quinolones, may form complexes with manganese that reduce the absorption of both substances.

Other supplements: High doses of calcium, iron, or zinc supplements may interfere with manganese absorption. Taking these supplements at different times may help minimize interactions.

Who should be cautious

Individuals with liver disease should exercise caution with manganese supplements, as impaired liver function can lead to manganese accumulation and increased risk of toxicity. People with iron deficiency may have increased manganese absorption, potentially leading to excessive levels.

Those taking multiple mineral supplements should be aware of potential interactions and consider spacing doses throughout the day. Individuals exposed to manganese in occupational settings (welding, mining, battery manufacturing) should be particularly cautious about additional supplementation.

Infants and young children are more susceptible to manganese toxicity and should not receive supplements unless specifically recommended by a pediatrician.

Frequently asked questions

Can I get enough manganese from food alone?

Yes, most people can easily meet their manganese needs through a balanced diet that includes whole grains, nuts, vegetables, and fruits. Deficiency is rare in developed countries when eating a varied diet.

Is manganese supplementation necessary for bone health?

While manganese plays a role in bone health, supplementation is typically unnecessary unless there’s a documented deficiency. A balanced diet with adequate calcium, vitamin D, and other bone-supporting nutrients is usually sufficient.

Can too much manganese cause neurological problems?

Yes, chronic exposure to high levels of manganese can cause manganism, a neurological condition with symptoms similar to Parkinson’s disease. This typically occurs with occupational exposure or excessive supplementation, not from dietary sources.

Should I take manganese supplements if I’m vegetarian?

Vegetarians often have adequate or even higher manganese intake than non-vegetarians due to greater consumption of whole grains, nuts, and vegetables. Supplementation is usually unnecessary unless recommended by a healthcare provider.

How do I know if I’m getting enough manganese?

Manganese deficiency is rare, but signs might include poor bone growth, skin problems, altered hair color, and impaired glucose tolerance. If concerned, consult a healthcare provider who can assess your dietary intake and overall health status.