Manganese – Bone Development, Antioxidation, and Glucose Metabolism

Manganese is an essential trace element that functions as a cofactor for a number of important enzymes. It plays a central role in bone development, antioxidant protection of mitochondria, and carbohydrate metabolism.

Biochemical Functions

Enzyme/Process	Function
Manganese Superoxide Dismutase (Mn-SOD)	Mitochondrial antioxidant protection – neutralizes superoxide in mitochondria
Pyruvate Carboxylase	Gluconeogenesis and fatty acid synthesis; manganese-dependent
Arginase	Urea cycle – breakdown of ammonia to urea
Glycosyltransferases	Synthesis of proteoglycans for cartilage and connective tissue
Glutamine Synthetase	Ammonia detoxification in the brain

Daily Requirement, Sources, and Bioavailability

Group	Estimated Value
Adult Men	2.3 mg/day
Adult Women	1.8 mg/day
Pregnant Women	2.0 mg/day
Lactating Women	2.6 mg/day

Best Food Sources

Food	Manganese mg/100g
Pecans	4.5 mg
Whole Wheat Flour	3.8 mg
Wheat Bran	11.5 mg
Oats	3.6 mg
Blueberries	0.6 mg
Black Tea (brewed)	0.5 mg/100ml
Edamame	1.0 mg

Important: Phytates in whole grains simultaneously inhibit manganese absorption. Tea and coffee also inhibit due to polyphenols. Actual bioavailability is usually 3–8%.

Manganese and Bones

Manganese is essential for the synthesis of glycosaminoglycans (GAGs) – the structural molecules in cartilage, bone, and connective tissue. GAGs like chondroitin and heparan form the basic framework of the bone matrix. Manganese deficiency impairs bone formation and leads to skeletal deformities in animals.

Neurotoxicity in Excess

Manganism: Chronic manganese overexposure (industrial exposure, contaminated water) causes a Parkinson's-like illness with tremor, gait disturbances, and psychosis. Normal dietary intake is harmless. For supplements: Upper tolerable limit = 11 mg/day (EFSA). Individuals with liver diseases have reduced manganese excretion and an increased risk of toxicity.

Frequently Asked Questions (FAQ)

Is manganese included in normal multivitamin supplements?

Yes, most multivitamin supplements contain 1–5 mg of manganese. A separate manganese supplement is rarely needed with a normal mixed diet.

Connection between manganese and diabetes?

Pyruvate carboxylase (manganese-dependent) is important for gluconeogenesis and indirectly for insulin signaling. Some studies show lower manganese levels in type 2 diabetics, but the causal relationship is not yet fully understood.