Manganese

  • Manganese (Mn) is an essential trace element for higher animals including humans.
  • Required for the activity of several enzymes in the intermediate metabolism (pyruvate carboxylase, succinate dehydrogenase and glutamine synthetase). It also plays a crucial role in glycogen synthesis. Mn2+ is bound to protein glycogenin, which serves as a primer for glycogen synthesis. The primer must be a least 8 glucose units long for glycogen synthase to start adding more glucose units to it. Mn2+ is believed to act as an electron-pair acceptor (Lewis acid).
    Glycogenin (Mn2+) + UDP-glucose ------> Glycogenin (Mn2+)-glucose + UDP
    When the glucose chain has reached at least 8 residues, glycogen synthase takes over and starts adding more glucose units to the non-reducing end of the growing saccharide chain.
  • Essential for the activity of Mn-dependent mitochondrial superoxide dismutase. It has been shown that MnSOD activity is decreased in conditions such as cancer, asthma and transplant rejection (1). On the other hand, overexpression of MnSOD inhibited tumor growth in many cell types (2). Mitochondrial decay has been linked to increased leakage of oxygen reactive species (O2-) from the electron transport chain and this is a critical factor in the aging process (3).
  • Mn ascorbate together with glucosamine and chondroitin sulfate were able to retard the progression of cartilage degeneration in a rabbit model of osteoarthritis (4). Supplementation with either agent alone was much less effective than the three of them administered together to the animals.
  • As demonstrated in adipose tissue culture Mn exhibits an insulin-mimetic effect when added to the tissue culture, i.e. causes an increased oxidation of glucose and a subsequent increase in lipogenesis (5).
  • Exhibits antioxidant properties by inhibiting the Fe2+-induced lipid peroxidation in the nigrostriatal system in the brain even in the absence of MnSOD (6).
  • Interactions: High magnesium, calcium, iron, copper and zinc may inhibit the absorption of manganese. High fiber intake may also inhibit manganese absorption.
  • Health benefits: Supplementation may be useful in conditions, such as strains, inflammation, diabetes and neurological disorders(epilepsy).
  • Best food sources: Nuts, whole grains, green leafy vegetables, tea.


References
1. MacMillan-Crow, L.A. & Cruthirds, D.L. (2001) Free Radic.Res. 34(4) 325-336. Invited review: manganese
    superoxide dismutase in disease.
2. Kim, K.H. et al. (2001) Antioxid. Redox Signal. 3(3) 361-373. Potential mechanisms for the inhibition of tumor
    cell growth.
3. Shigenaga, M.K. et al. (1994) Proc.Natl.Acad.Sci. USA 91(23) 10771-10778. Oxidative damage and
    mitochondrial decay in aging.
4. Lippiello, L. et al. (2000) Clin.Orthop.Relat.Res. 381 (229-240). In vivo chondroprotection and metabolic synergy
    of glucosamine and chondroitin sulfate.
5. Baquer, N.Z. et al. (2003) J.Biosci. 28(2) 215-221. Regulation of glucose utilization and lipogenesis in adipose
    tissue of diabetic and fat-fed animals: effects of insulin and manganese.
6. Sziraki, I. et al. (1998) Neuroscience 85(4) 1101-1111. Manganese: a transition metal protects nigrostriatal
    neurons from oxidative stress in the iron-induced animal model of parkinsonism.