Manganese is an essential trace mineral required by the human body. As a component of many enzymes, this micronutrient participates in various metabolic and cellular processes. While deficiency is rare, recognizing the signs is important for individuals with underlying risk factors or specific dietary restrictions.
Physiological Role of Manganese in the Body
Manganese serves as a cofactor for several classes of enzymes that accelerate biochemical reactions throughout the body. One significant role is as a component of manganese superoxide dismutase (MnSOD), a primary antioxidant enzyme located within the mitochondria. This enzyme neutralizes free radicals, protecting the cell’s energy-producing centers from oxidative damage.
Manganese acts as an activator for enzymes like pyruvate carboxylase, necessary for producing glucose from non-carbohydrate sources. It is required for the urea cycle, which detoxifies ammonia generated during amino acid breakdown. Furthermore, it is necessary for the synthesis of cholesterol and fatty acids.
Manganese plays a direct role in forming and maintaining connective tissue and bone structure. It activates glycosyltransferases, enzymes that produce the sugar chains needed for cartilage and bone matrix formation. It is also required for prolidase, which supplies the amino acid proline, a building block for collagen synthesis. Approximately 25% to 40% of the body’s total manganese is stored within the bones.
Recognizing Signs of Manganese Deficiency
Skeletal issues are a common manifestation, particularly in children, presenting as impaired growth, poor bone formation, and skeletal defects. In adults, low manganese levels may contribute to bone demineralization and joint pain.
Metabolic disturbances include an impaired ability to process glucose, leading to abnormal glucose tolerance. Alterations in lipid metabolism can be observed as decreased serum cholesterol concentration. Since manganese is involved in neurotransmitter synthesis, neurological symptoms can occur, such as altered mood states or, in severe cases, poor coordination (ataxia).
Dermatological signs include a transient skin rash and depigmentation of hair color. Because of the mineral’s role in collagen production, deficiency can contribute to delayed or poor wound healing. In women, low manganese levels are associated with increased pain and mood changes during the premenstrual phase.
Dietary Sources and Risk Factors for Deficiency
Manganese is widely distributed in plant-based foods. High-concentration sources include:
- Whole grains
- Nuts
- Seeds
- Legumes
- Leafy green vegetables
- Black tea
Shellfish, such as mussels and oysters, also provide significant amounts of the mineral.
Certain physiological conditions and dietary patterns can increase the risk for deficiency by inhibiting absorption. Iron and manganese compete for the same intestinal transport protein (DMT-1); thus, high iron intake or supplementation can reduce manganese absorption. Similarly, compounds like phytic acid in grains and oxalic acid in spinach can bind to manganese and limit its uptake.
Individuals with gastrointestinal disorders causing malabsorption, such as Crohn’s disease or celiac disease, are at greater risk. Restrictive diets that exclude major manganese sources, like whole grains and nuts, can also lead to inadequate intake. Chronic alcoholism and smoking are also associated with lower circulating manganese levels.
Clinical Diagnosis and Management
Diagnosing manganese deficiency is challenging because symptoms are often non-specific, and routine blood tests are not always reliable. Since the body tightly regulates manganese levels, plasma concentrations fluctuate widely. Whole blood or Red Blood Cell (RBC) measurements are considered a more stable and accurate biomarker, with normal concentrations typically ranging from 4 to 15 micrograms per liter.
Management of a confirmed deficiency involves increasing the intake of manganese-rich foods, often supplemented by a short course of oral supplementation. For adults, a typical oral dose is between 2 and 3 milligrams per day.
Supplementation must be closely supervised due to the risk of toxicity, especially in people with liver impairment who cannot excrete excess manganese. Monitoring whole blood manganese levels helps track the response to treatment, with re-testing recommended after a 40-day interval. The goal is to restore normal levels without causing accumulation, which can lead to neurological issues.