Possible Interaction: Methionine and Racemethionine

“Plasma methionine levels were higher (9.9 +/- 1.9 mumoles/100 ml) in patients infused with solutions containing DL-methionine than those infused with the L-methionine solution (4.5 +/- 1.0 mumoles/100 ml).”

“This practice was further justified by the observations that the ingestion of dl-methionine by normal individuals resulted in a prompt elevation of the methionine level in the urine, as determined by our method.”

“Dietary supplementation with dl-Met could be a promising tool to improve the absorption of Met and other AAs.”

“Expression of betaine-homocysteine methyltransferase (BHMT), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and 5,10 methylenetetrahydrofolate reductase (MTHFR) genes, which catalyze regeneration of Met from betaine and homocysteine, decreased linearly with increasing dl-Met concentration.”

“The use of DLM enhanced the plasma methionine concentration (P < 0.01) and increased the heterophil/lymphocyte ratio (P < 0.05).”

“Portal infusion of 5, 10, and 15 g/d of DL-Met increased plasma total Met concentrations (19.7, 25.0, and 34.4±0.6 μM) and the proportion of Met as D (19.4, 30.5, and 37.3±0.7%).”

“Plasma-free Met increased at 3 times the rate for DLM than HMTBA (P <0.01) with increasing Met concentration, which may play a role in the evolution of different dose responses at the extremes of the Met dose response.”

“Three weeks after feeding 2% DL-methionine the plasma methionine was elevated > 20-fold, whereas plasma homocysteine was more than 3-fold normal plasma values.”

“These results indicated that abomasal administration of .333 g of DL-methionine/kg BW per day induced methionine toxicity at Stage 2 but methionine imbalance at Stage 1.”

“Dietary addition of .50% DL-methionine caused normalization of plasma glycine levels whereas it elevated plasma methionine concentration.”