Research
L-Methionine
33 peer-reviewed studies curated from PubMed and Semantic Scholar.
Studies
Sorted by quality and recency
The Association of the Essential Amino Acids Lysine, Methionine, and Threonine with Clinical Outcomes in Patients at Nutritional Risk: Secondary Analysis of a Randomized Clinical Trial.
Secondary analysis of the EFFORT trial examining the impact of lysine, methionine, and threonine metabolism on clinical outcomes in 237 patients at nutritional risk. Low plasma methionine levels were associated with increased 30-day mortality and decline in functional status, suggesting methionine's critical role during hospitalization.
[The results of phase III multicenter open randomized controlled study REM-Chol-III-16 in patients with intrahepatic cholestasis syndrome caused by chronic diffuse liver diseases].
Phase III multicenter open-label RCT comparing the safety and efficacy of Remaxol (inosine + meglumine + methionine + nicotinamide + succinic acid) to Heptral (S-adenosyl-L-methionine) in 317 patients with intrahepatic cholestasis syndrome. Remaxol demonstrated similar efficacy to Heptral in improving liver function parameters, with no significant differences in adverse events.
Effects of feed grade L-methionine on intestinal redox status, intestinal development, and growth performance of young chickens compared with conventional DL-methionine.
This study tested the effects of supplemental L-Met on redox status, gut development, and growth performance of young broiler chickens compared with DL-Met. L-Met supplementation improved gut health, antioxidant capacity, and growth performance more effectively than DL-Met.
A Phase I Trial of a Methionine Restricted Diet with Concurrent Radiation Therapy.
Phase I trial evaluating the safety and feasibility of a methionine restricted diet (MRD) with concurrent radiation therapy (RT) in adults with non-skin cancer malignancies. Nine patients were accrued, with five completing the treatment. No grade 3 or higher adverse events were observed, but the diet was challenging for most patients.
Metabolic Availability of Methionine Assessed Using Indicator Amino Acid Oxidation Method, Is Greater when Cooked Lentils and Steamed Rice Are Combined in the Diet of Healthy Young Men.
The study assessed the metabolic availability of methionine in lentils and the effects of combining lentils with rice in the diet of healthy young men. The metabolic availability of methionine from lentils was found to be 69%, and complementation with rice improved protein quality by decreasing phenylalanine oxidation.
Bioavailable Methionine Assessed Using the Indicator Amino Acid Oxidation Method Is Greater When Cooked Chickpeas and Steamed Rice Are Combined in Healthy Young Men.
The study assessed methionine bioavailability in rice and chickpeas separately and in combination using the indicator amino acid oxidation method in 11 healthy young men. Methionine bioavailability was 100% from rice and 63% from chickpeas, with complementation of chickpeas with rice improving protein quality.
L-Methionine associated with Hibiscus sabdariffa and Boswellia serrata extracts are not inferior to antibiotic treatment for symptoms relief in patients affected by recurrent uncomplicated urinary tract infections: Focus on antibiotic-sparing approach.
This randomized phase III clinical trial evaluated the efficacy of a phytotherapic combination of L-Methionine, Hibiscus sabdariffa, and Boswellia serrata for treating acute episodes of uncomplicated urinary tract infections in women. The study found that the phytotherapy group showed significant improvement in quality of life scores and a higher transition to asymptomatic bacteriuria compared to the antibiotic group, suggesting potential benefits in an antibiotic-sparing approach.
Gene expression differences in the methionine remethylation and transsulphuration pathways under methionine restriction and recovery with D,L-methionine or D,L-HMTBA in meat-type chickens.
This study examined the molecular mechanisms of methionine pathways in meat-type chickens under methionine restriction and recovery with D,L-methionine or D,L-HMTBA. Gene expression in various tissues indicated differences in remethylation and transsulphuration pathways depending on methionine form and tissue type.
Effect of feed grade L-methionine on growth performance and gut health in nursery pigs compared with conventional DL-methionine.
Two experiments tested the effects of L-methionine supplementation on growth performance and gut health in nursery pigs compared to DL-methionine. L-methionine improved average daily gain, reduced plasma urea nitrogen, and enhanced duodenum villus development and oxidative stress markers, suggesting better bioavailability and nutritional benefits over DL-methionine.
Effect of L-methionine on hot flashes in postmenopausal women: a randomized controlled trial.
RCT investigating the effects of L-methionine on hot flashes in 51 postmenopausal women. No significant differences were found between L-methionine and placebo groups in reducing hot flash composite scores. L-methionine therapy was ineffective for treating hot flashes.
DL-Methionine is as efficacious as L-methionine, but modest L-cystine excesses are anorexigenic in sulfur amino acid-deficient purified and practical-type diets fed to chicks.
Three bioassays were conducted to compare the effects of dietary cystine on the efficacy of L-Met and DL-Met in chicks. Methionine supplementation improved growth performance, while cystine supplementation reduced weight gain and feed intake but increased gain:feed ratio. No differences were found between L-Met and DL-Met effectiveness.
Treatment of AIDS-associated myelopathy with L-methionine: a placebo-controlled study.
A Phase II, double-blind, placebo-controlled study of 56 patients with AIDS-associated myelopathy (AM) comparing l-methionine 6 g/day to placebo over 12 weeks. L-methionine was safe and well tolerated, with a nonsignificant improvement in central conduction time (CCT) but no benefit in clinical measures such as strength, spasticity, or urinary function.
Hepatic Activity and Transcription of Betaine-Homocysteine Methyltransferase, Methionine Synthase, and Cystathionine Synthase in Periparturient Dairy Cows Are Altered to Different Extents by Supply of Methionine and Choline.
This study investigated the effects of methionine and choline supplementation on hepatic enzyme activity and transcription in periparturient dairy cows. Methionine supplementation led to increased expression of certain enzymes and improved immuno-metabolic status, while choline did not produce comparable effects.
13C-methionine breath tests for mitochondrial liver function assessment.
The study compared two differently 13C-labeled methionines in evaluating mitochondrial oxidation in basal conditions and after acute oxidative stress in 15 healthy male subjects. The breath test using L-methionine-1-13COOH showed a higher cumulative percentage of 13CO2 recovered in breath compared to [methyl-13C]-methionine, indicating greater reliability for assessing mitochondrial function.
Effect of L-methionine supplementation on plasma homocysteine and other free amino acids: a placebo-controlled double-blind cross-over study.
A placebo-controlled double-blind cross-over study investigated the effects of L-methionine supplementation on plasma homocysteine and other amino acids in 8 female patients with chronic urinary tract infection and 12 healthy women. L-methionine supplementation significantly increased homocysteine plasma concentrations and renal excretion of methionine and homocysteine.
Effects of acute hyperhomocysteinemia on the neurovascular coupling mechanism in healthy young adults.
RCT testing the effects of methionine and folic acid on neurovascular coupling in 15 healthy young adults. Homocysteine levels increased significantly, but resting flow velocities and control system parameters remained statistically nonsignificant, suggesting a wider compensatory range in cerebral blood flow regulation compared to peripheral vasculature.
Investigation of relationship between reduced, oxidized, and protein-bound homocysteine and vascular endothelial function in healthy human subjects.
RCT investigating the relationship between different forms of homocysteine and vascular endothelial function in 14 healthy volunteers. Oral loading with L-methionine and L-homocysteine increased homocysteine concentrations and reduced flow-mediated dilatation, indicating endothelial dysfunction. Reduced homocysteine was closely associated with this dysfunction, while other forms were not.
Methionine in paracetamol tablets, a tool to reduce paracetamol toxicity.
The study compared the analgesic effect, toxicity, and kinetics of oral paracetamol with paracetamol + l-methionine in rats and mice. Methionine did not change the analgesic effect but reduced the acute toxicity of paracetamol by 50% in mice. In a human volunteer study, methionine did not affect paracetamol pharmacokinetics but was rapidly absorbed.
Plasma and urinary methionine levels in one-year-old infants after oral loading with L-methionine and N-acetyl-L-methionine.
The study administered L-methionine and N-acetyl-L-methionine to fasting 1-year-old infants in a randomized crossover design to compare methionine release to the blood. Both compounds produced equivalent methionine release, but infants showed lower plasma methionine concentrations compared to adults, suggesting more rapid metabolism in infants.
Acute hyperlipidemia but not hyperhomocysteinemia impairs reflex regulation of the cardiovascular system.
RCT involving 25 healthy men to assess the effects of hyperlipidemia and hyperhomocysteinemia on cardiovascular function. Hyperlipidemia significantly decreased baroreflex sensitivity and increased heart rate and sympathetic drive, while hyperhomocysteinemia showed no significant effects.
Use of antioxidants to treat pain in chronic pancreatitis.
A 1-year clinical study using antioxidant therapy in patients with chronic and acute recurrent pancreatitis showed reduced pain intensity and fewer hospital admissions. The treatment included L-methionine, beta-carotene, vitamin C, vitamin E, and organic selenium.
Physiological increments in plasma homocysteine induce vascular endothelial dysfunction in normal human subjects.
RCT studying the effects of low-dose oral methionine and dietary animal protein on plasma homocysteine levels and vascular endothelial function in 18 healthy volunteers. Methionine and animal protein increased homocysteine levels and reduced flow-mediated dilatation, suggesting potential negative effects on vascular function.
A pilot study of L-methionine for the treatment of AIDS-associated myelopathy.
Pilot clinical trial of L-methionine in 12 patients with AIDS-associated vacuolar myelopathy (VM). Seven of the nine patients who completed the study showed clinical and electrophysiologic improvement, suggesting potential efficacy of L-methionine in VM.
[Prevention of reinfection by L-methionine in patients with recurrent urinary tract infection].
RCT involving 33 female patients with recurrent urinary tract infections, comparing L-methionine (Acimethin) to nalidixic acid. L-methionine treatment prevented acute infections and maintained normal inflammation parameters, reducing bacterial adherence to uroepithelial cells.
[Clinical evaluation of anticancer effect of methionine-depleting total parenteral nutrition with 5-fluorouracil and/or mitomycin C].
RCT evaluating methionine-depleting total parenteral nutrition (Met-deplete TPN) with AO-90 amino acid solution in advanced gastric cancer patients. The RT group receiving Met-deplete TPN showed a higher clinical response rate compared to the control group, with significant differences in histological response.
Synergistic effect of methionine-depleting total parenteral nutrition with 5-fluorouracil on human gastric cancer: a randomized, prospective clinical trial.
RCT of methionine-depleting total parenteral nutrition (Met-depleting TPN) combined with 5-fluorouracil (5-FU) in 14 preoperative advanced gastric cancer patients. The AO-90 group showed marked degeneration of cancer and decreased thymidylate synthase activity compared to the control group.
Effects of equimolar doses of L-methionine, D-methionine and L-methionine-dl-sulfoxide on plasma and urinary amino acid levels in normal adult humans.
Randomized crossover study measuring plasma and urinary amino acid levels in four adults after administration of L-methionine, D-methionine, and L-methionine-dl-sulfoxide. Plasma methionine levels increased significantly after loading with each compound, with D-methionine showing the highest plasma levels. Urinary methionine excretion was significantly higher after D-methionine ingestion, indicating inefficient utilization of D-methionine as a methionine source.
Methionine fortification of a soy protein formula fed to infants.
RCT comparing soy protein formula with and without L-methionine supplementation in 19 full-term infants. Infants fed the methionine-supplemented formula showed better growth and serum chemical values compared to those fed the unsupplemented formula.
Dietary tryptophan and methionine as modulators of European seabass (Dicentrarchus labrax) immune status and inflammatory response.
The study evaluated the effects of dietary supplementation of tryptophan and methionine on the immune status and inflammatory response of European seabass. Methionine positively affected immune status by improving leucocyte response, complement activity, and bactericidal capacity, while tryptophan showed trends of immunostimulation but failed to improve inflammatory response.
A moderate increase in daily protein intake causing an enhanced endogenous insulin secretion does not alter circulating levels or urinary excretion of dehydroepiandrosterone sulfate.
A randomized crossover trial with six healthy male volunteers studied the effect of increased protein intake and methionine supplementation on insulin secretion and DHEAS levels. Despite increased insulin secretion, plasma and urinary levels of DHEAS remained unaffected.
Methionine synthase deficiency: Variable clinical presentation and benefit of early diagnosis and treatment
The paper discusses methionine synthase deficiency (cblG complementation group), a rare metabolic disorder affecting homocysteine re-methylation. It presents five patients who showed clinical improvement with treatment, including methionine supplementation, highlighting the benefit of early diagnosis and treatment in improving neurologic outcomes.
The effect of finishing diet supplemented with methionine/lysine and methionine/α-tocopherol on performance, carcass traits and meat quality of Hanwoo steers
The study compared the effects of diets supplemented with methionine/lysine and methionine/α-tocopherol on Hanwoo steers. Methionine/lysine supplementation improved water holding capacity and protein content without affecting performance or carcass traits. Methionine/α-tocopherol supplementation resulted in redder meat, reduced lipid oxidation, and increased protein and oxymyoglobin content.
Absorption of L-methionine from the human small intestine.
Study measured absorption of L-methionine in different parts of the human small intestine using transintestinal intubation and perfusion. In normal subjects, absorption was higher in the proximal intestine, while in patients with nontropical sprue, absorption was higher distally. Absorption showed rate-limiting kinetics as methionine concentration increased.