- Manganese is an important factor in many critical biochemical processes including antioxidant function.

- Manganese is a mineral element that is both nutritionally essential and has the potential to be very toxic. This fact is further complicated by the small range of dosage for clinical benefit and toxicity with serious consequences.

- The principle antioxidant enzyme within our mitochondria (energy) is superoxide dismutase and the enzymes requires manganese for optimal performance.

- Manganese is also required for normal skeletal development and cartilage synthesis.

- Wound healing is also impacted by manganese, as the synthesis of collagen in skin cells is dependent on the presence of adequate manganese.

- Manganese is also important functioning as a co-factor in the metabolism of carbohydrates, amino acids and cholesterol.

- Manganese is considered anti-osteoporotic and anti-arthritic.

-------------------------

Sources:

Whole grains (wheat germ, oats and bran), rice, and nuts (hazelnuts, almonds, and pecans) contain the highest amounts of Mn. Other food sources include chocolate, tea, mussels, clams, legumes, fruit, leafy vegetables (spinach), seeds (flax, sesame, pumpkin, sunflower, and pine nuts) and spices (chili powder, cloves and saffron).

Airborne exposure can occur through automobile exhaust, unleaded gasoline and occupational exposure(mining, welding, ferroalloy and steel industry, battery manufacturing). It is also present in fungicides, textile bleaching, manufacture of glass and ceramics, paint, matches and fireworks, leather tanning, hydroquinone, potassium permanganate and other chemical production. Soil manganese concentrations can contaminate well water.

Absorption factors:

Only about 1 to 5% of dietary Mn is absorbed in the gut. Absorption is influenced by intestinal pH, the presence of divalent metal transporter DMT1, other divalent metals competing for absorption (iron, copper, zinc, calcium) and phytic acid.119 The absorption of Mn is tightly regulated in the gut and therefore toxicity from diet has not been reported.

Iron deficiency increases Mn absorption.

Supplemental magnesium (200mg/day) may decrease Mn availability by decreasing absorption or increasing excretion. Mn is eliminated mainly via bile.

Biochemical actions:

Required for immune function, regulation of blood sugar and cellular energy, reproduction, digestion, bone growth, blood coagulation, hemostasis, wound healing andantioxidant.

Mn is incorporated into metalloproteins, such as superoxide dismutase and others.

Symptoms of imbalance:

Mn deficiency is rare and results in impaired growth, poor bone formation and skeletal defects, abnormal glucose tolerance, altered lipid and carbohydrate metabolism, dermatitis, slowed hair/nail growth.

Diseases reported with low blood Mn concentrations include epilepsy, Mseleni disease, Down’s syndrome, osteoporosis and Perthest disease.

Individuals with increased susceptibility to manganese toxicity include patients with chronic liver disease, newborns and children, iron-deficient populations, patients on parenteral nutrition, and occupational exposure.

Mn is neurotoxic and excess levels have been associated with Parkinson’s-like symptoms. A blood Mn level may provide the best estimate for brain Mn levels when exposure is recent. Mn toxicity is generally due to environmental or occupational exposures including airborne (inhaled) and drinking water.

Periods of occupational exposure of 6 months to 2 years may lead to manganism and the motor and neuropsychiatric symptoms may remain several years after the exposure. Symptoms include dystonia, bradykinesia and rigidity (due to damage to dopaminergic neurons) and gliosis.

Additional symptoms include tremors, muscle spasms, tinnitus, hearing loss, ataxia, mania, insomnia, depression, delusions, anorexia, headaches, irritability, lower extremity weakness, changes in mood or short-term memory, altered reaction times and reduced hand-eye coordination.

References:

Peres TV, Schettinger MR, Chen P, et al. “Manganese-induced neurotoxicity: a review of its behavioral consequences and neuroprotective strategies”. BMC Pharm Toxicol. 2016;17(1):57.

Aschner M, Erikson K. Manganese. Adv Nutr. 2017;8(3):520-521.

Avila DS, Puntel RL, Aschner M. Manganese in health and disease. Metal ions in life sciences. 2013;13:199-227.

Erikson KM, Aschner M. Manganese: Its Role in Disease and Health. Metal ions in life sciences. 2019;19.

University OS. Manganese. Linus Pauling Institute - Micronutrient Information Center - Minerals 2020; https://lpi. oregonstate.edu/mic/minerals/manganese, 2020.

NIH. Manganese Fact Sheet for Health Professionals. Dietary Supplement Fact Sheets 2020; https://ods.od.nih.gov/ factsheets/Manganese-HealthProfessional/, 2020.