Methylselenocysteine: The Preferred Form of Selenium
Methylsenocysteine (MSC) is a relatively simple organic
selenium compound formed naturally in various plants, including garlic, wild
leeks, onions and broccoli grown on high selenium soil.[1]
It is the preferred form of selenium for a few different reasons. First, for
the past 15 years or so, selenium research on the incidence of cancer cell
development has focused heavily on MSC, and MSC rich foods have shown good
activity in reducing the incidence of cancer cell development without excess
tissue accumulation or toxicity.[2]
Second, MSC is easily converted to methylselenol[3],
and methylselenol has been shown to reduce cancer cell development through a
process called apoptosis, or
programmed cell death. Cells eliminated by apoptosis don't leave a messy
residue to trigger inflammation and spread cell death. Methylselenol is also
known to reduce angiogenesis, the growth of new blood vessels necessary to
promote the development of cancer cells.[4]
Third, MSC is a relatively nontoxic form of selenium.
Consider that selenite/selenate forms of selenium (e.g. sodium selenite) are
more frequently metabolized to the toxic metabolite hydrogen selenide (H2Se).[5]
Then consider that because cells cannot distinguish selenomethionine from the
essential amino acid methionine, some selenomethionine become incorporated into
general body proteins, increasing tissue selenium levels which may risk
toxicity[6]. By contrast, once
methylselenol is formed from MSC, it is soon transformed into dimethylselenide,
which is rapidly excreted in the breath, or converted to trimethylselenonium,
which is thoroughly excreted in the urine.[7]
References
[1] Whanger,
P. Selenocompounds in plants and animals and their biological significance. J
Am Coll Nutr 2002, 21:223-32.
[2] Ip, C.
and Lisk, D. Characterization of selenium profiles and anticarcinogenic
responses in rats fed natural sources of selenium-rich products. Carcinogenesis
1994, 15:573-76.
[3] Medina,
D. et al. Se-methylselenocysteine: A new compound for chemoprevention of breast
cancer. Nutr Cancer 2001, 40:12-17.
[4] Lu, J.
and Jiang, C. Antiangiogenic activity of selenium in cancer chemoprevention:
metabolite-specific effects. Nutr Cancer 2001, 40:64-73.
[5]
Passwater, R. Selenium Against Cancer and AIDS. New
Canaan CT: Keats, 1996:47-48.
[6] Ip, C.
Lessons from basic research in selenium and cancer prevention. J Nutr 1998,
128:1845-54.
[7] Satyanarayana S, Sekhar JR, Kumar KE, Shannika LB,
Rajanna B, Rajanna S. Influence of selenium
(antioxidant) on gliclazide induced hypoglycaemia/anti hyperglycaemia in
normal/alloxan-induced diabetic rats. Mol Cell Biochem. 2006;283:123-7.