Possible Interaction: Homocysteine and Methionine

“A high protein intake and hence a high intake of methionine --the sole dietary precursor of homocysteine--may raise plasma tHcy concentrations.”

“Conclusions:Despite an adequate vitamin status, the supplementation of 1500 mg of L-methionine daily significantly increases homocysteine plasma concentrations by an average of 2.0 μmol/l in patients and in control subjects.”

“Simultaneously, renal excretion of methionine and homocysteine was significantly higher during L-methionine intake.”

“However, the methionine load from the dialysate in this study significantly elevated plasma Hcy levels, especially in patients with lower protein and methionine intakes, and lower AST levels.”

“Endothelial function as assessed by flow-mediated dilatation (FMD) of the brachial artery was impaired after both the methionine and homocysteine load compared with placebo at 4 hours (36 +/- 15, 67 +/- 23 vs 219 +/- 26 microm, respectively, P < .001).”

“Results Oral methionine induced a significant increase in plasmatic levels of homocysteine.”

“The increase in tHcy induced by methionine , the sole dietary precursor of homocysteine, might be modulated by other amino acids present in dietary proteins.”

“RESULTS After me hionine lo ad, pla sma homocysteine in creased from 10.7 +/- 2.8 mumol/L to 30.4 +/- 5.1 mumol/L ( P < .0001) and CFR decreased from 3.0 +/- 0.4 to 2.3 +/- 0.3 ( P < .001).”

“Differences in mean SAC values when plasma homocysteine concentrations were raised with a methionine containing meal and on another day when a control meal was eaten were highly significant.”

“Furthermore, the total plasma levels of homocysteine were higher, whereas those of cysteine were lower, after methionine loading in both groups.”

“Our results suggest that methionine loading may initiate the generation of reactive oxygen species by the (auto)-oxidation of homocysteine.”

“ Homocysteine concentrations are thought to be raised by high protein and methionine intakes.”