Betaine for Glutathione? Unclear....

Date:   2/4/2009 11:26:55 AM ( 15 y ago)

i am coming across conflicting data on whether or not supplementing with betaine will raise glutathione levels. by the way betaine is sold in supplemental form labeled as TMG or DMG wich is short for tri- or di- methylglycine.

one study says administration of betaine initially lowers GSH levels, then raises them. another study says GSH levels remain constant but betaine does encourage recycling of homocysteine which is a good thing.

i pulled out the two main quotes from the two studies.

--"In conclusion the present results indicate that betaine administration induces time-dependent changes on hepatic metabolism of S-amino acids. Betaine enhances metabolic reactions in the methionine cycle, but inhibits cystathionine synthesis and cysteine uptake, leading to a decrease in supply of cysteine for glutathione synthesis. Reduction in glutathione is subsequently reversed due to induction of cysteine synthesis and glutamate cysteine ligase activity"--



---"Betaine supplementation enhances recycling of homocysteine for the generation of methionine and S-adenosylmethionine while reducing its utilization for the synthesis of cystathionine and cysteine. However, the hepatic levels of cysteine or glutathione are not affected, most probably due to the depression of taurine generation from cysteine."--



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http://www.ncbi.nlm.nih.gov/pubmed/15885362?dopt=AbstractPlus


Effect of acute betaine administration on hepatic metabolism of S-amino acids in rats and mice
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Sang K. Kima, Kwon H. Choia and Young C. KimCorresponding Author Contact Information, E-mail The Corresponding Author, a, b

Abstract

Alterations of hepatic glutathione level by betaine were observed previously. In this study effects of betaine administration (1000 mg/kg, i.p.) on S-amino acid metabolism in rats and mice were investigated. Hepatic glutathione level decreased rapidly followed by marked elevation in 24 hr. Concentrations of S-adenosylmethionine, S-adenosylhomocysteine, and methionine were increased whereas cystathionine decreased significantly, suggesting that homocysteine generated in the methionine cycle is preferentially remethylated to methionine rather than being utilized for synthesis of cysteine. Hepatic cysteine concentration declined immediately, but plasma cysteine increased. Effect of betaine on hepatic cysteine uptake was estimated from the difference in cysteine concentration in major blood vessels connected to liver. Cysteine concentration either in the portal vein or abdominal aorta was not altered, however, a significant increase was noted in the hepatic vein, indicating that hepatic uptake of cysteine was decreased by betaine treatment. Activities of glutamate cysteine ligase, cystathionine β-synthase, and cystathionine γ-lyase were elevated in 24 hr. Pretreatment with propargylglycine, an irreversible inhibitor of cystathionine γ-lyase, did not abolish the betaine-induced reduction of hepatic glutathione in 4 hr, however, the elevation at t=24 hr was blocked completely. In conclusion the present results indicate that betaine administration induces time-dependent changes on hepatic metabolism of S-amino acids. Betaine enhances metabolic reactions in the methionine cycle, but inhibits cystathionine synthesis and cysteine uptake, leading to a decrease in supply of cysteine for glutathione synthesis. Reduction in glutathione is subsequently reversed due to induction of cysteine synthesis and glutamate cysteine ligase activity



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http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T4P-48B5VTW-2&_use...


Effects of betaine supplementation on hepatic metabolism of sulfur-containing amino acids in mice.
Kim SK, Kim YC.

College of Pharmacy, Chungnam National University, Daijeon, 222 Gung-Dong, Yuseong-Ku, Daijeon, South Korea.

BACKGROUND/AIMS: We previously reported that acute betaine treatment induced significant changes in the hepatic glutathione and cysteine levels in mice and rats. The present study was aimed to determine the effects of dietary betaine on the metabolism of sulfur-containing amino acids. METHODS/RESULTS: Male mice were supplemented with betaine (1%) in drinking water for up to 3 weeks. Changes in hepatic levels of major sulfur amino acid metabolites and products were stabilized after 2 weeks of betaine supplementation.

Betaine intake increased methionine, S-adenosylmethionine, and S-adenosylhomocysteine levels significantly, but homocysteine and cystathionine were reduced. Methionine adenosyltransferase activity was elevated to three-fold of control. Cysteine catabolism to taurine was inhibited as evidenced by a decrease in cysteine dioxygenase activity and taurine levels in liver and plasma. Despite the significant changes in the transsulfuration reactions, neither hepatic cysteine nor glutathione was altered. Betaine supplementation decreased the hepatotoxicity induced by chloroform (0.5 ml/kg, ip) significantly. CONCLUSIONS: Betaine supplementation enhances recycling of homocysteine for the generation of methionine and S-adenosylmethionine while reducing its utilization for the synthesis of cystathionine and cysteine. However, the hepatic levels of cysteine or glutathione are not affected, most probably due to the depression of taurine generation from cysteine.

 

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