L-Methionine
Amino Acid ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
Essential sulfur-containing amino acid, precursor to SAMe and cysteine.
Exploratory record, not a reviewed medical publication.
See the editorial and medical-review policies for the publication gate.
This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.
What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
L-Methionine is an amino acid most often used for methylation, detoxification, joint health. NutriStack rates the overall evidence as moderate. A typical adult dose is 500-1,500 mg daily, commonly taken as l-methionine (free form). This profile indexes 17 sources.
The bottom line
Evidence rating moderate. Most-documented uses: methylation, detoxification, joint health. 17 sources indexed (1989–2024), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
Activated by methionine adenosyltransferase to SAMe. Enters transmethylation (SAMe→SAH), transsulfuration (cysteine→glutathione), and polyamine synthesis pathways.1,11
Dosing & protocol.
What it actually costs.
Real-world pricing across three quality tiers. Assumes L-Methionine Free Form.
Assumes 500-1,500 mg/day. Vendor basis: NOW/iHerb, Vitacost, BulkSupplements powder, and Amazon marketplace; capsules cost more than powder. Updated 2026-05-28.
The same dose, as food.
How much you'd eat to match a supplemental dose.
Whole foods supply methionine with other amino acids and micronutrients.
Full safety detail.
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Meta-analyses & systematic reviews
8- 1Efficacy and acceptability of S-adenosyl-L-methionine (SAMe) for depressed patients: A systematic review and meta- analysisPMIDLimveeraprajak N, Nakhawatchana S, Visukamol A et al. · Progress in neuro-psychopharmacology & biological psychiatry · 2024
Limveeraprajak N, Nakhawatchana S, Visukamol A et al.. Efficacy and acceptability of S-adenosyl-L-methionine (SAMe) for depressed patients: A systematic review and meta- analysis. Progress in neuro-psychopharmacology & biological psychiatry. 2024
- 2The Role of 11C-Methionine PET Imaging for the Evaluation of Lymphomas: A Systematic ReviewPMIDDondi F, Gazzilli M, Viganò GL et al. · Hematology reports · 2024
Dondi F, Gazzilli M, Viganò GL et al.. The Role of 11C-Methionine PET Imaging for the Evaluation of Lymphomas: A Systematic Review. Hematology reports. 2024
- 3Folate-Methionine Cycle Disruptions in ASD Patients and Possible Interventions: A Systematic ReviewPMIDRoufael M, Bitar T, Sacre Y et al. · Genes · 2023
Roufael M, Bitar T, Sacre Y et al.. Folate-Methionine Cycle Disruptions in ASD Patients and Possible Interventions: A Systematic Review. Genes. 2023
- 4Systematic review and meta-analysis of the methionine utilization efficiency in piglets receiving different methionine sourcesPMIDSouza VC, Remus A, Batonon-Alavo DI et al. · Animal : an international journal of animal bioscience · 2023
Souza VC, Remus A, Batonon-Alavo DI et al.. Systematic review and meta-analysis of the methionine utilization efficiency in piglets receiving different methionine sources. Animal : an international journal of animal bioscience. 2023
- 5Meta-Analysis of Rumen-Protected Methionine in Milk Production and Composition of Dairy CowsPMIDWei C, He T, Wan X et al. · Animals : an open access journal from MDPI · 2022
Wei C, He T, Wan X et al.. Meta-Analysis of Rumen-Protected Methionine in Milk Production and Composition of Dairy Cows. Animals : an open access journal from MDPI. 2022
- 6Vitamin B6, vitamin B12 and methionine and risk of pancreatic cancer: a meta-analysisPMIDWei DH, Mao QQ · Nutrition journal · 2020
Wei DH, Mao QQ. Vitamin B6, vitamin B12 and methionine and risk of pancreatic cancer: a meta-analysis. Nutrition journal. 2020
- 7Аdеmethionine in the treatment of fatigue in liver diseases: a systematic reviewPMIDRaikhelson KL, Kondrashina EA · Terapevticheskii arkhiv · 2019
Raikhelson KL, Kondrashina EA. Аdеmethionine in the treatment of fatigue in liver diseases: a systematic review. Terapevticheskii arkhiv. 2019
- 8Performance of 18F-FDG, 11C-Methionine, and 18F-FET PET for Glioma Grading: A Meta-analysisPMIDKatsanos AH, Alexiou GA, Fotopoulos AD et al. · Clinical nuclear medicine · 2019
Katsanos AH, Alexiou GA, Fotopoulos AD et al.. Performance of 18F-FDG, 11C-Methionine, and 18F-FET PET for Glioma Grading: A Meta-analysis. Clinical nuclear medicine. 2019
Randomized controlled trials
3- 9Effect of L-methionine supplementation on plasma homocysteine and other free amino acids: a placebo-controlled double-blind cross-over studyPMIDDitscheid B et al. · Eur J Clin Nutr · 2005
Supplementation of 1500 mg L-methionine daily significantly increased homocysteine plasma concentrations by 2.0 micromol/l despite adequate vitamin status.
- 10Methionine in the prevention and management of urinary tract infectionsSource linkedPMIDFünfstück R, Straube E, Schildbach O, Tietz U · Int J Antimicrob Agents · 1997
- 11Effects of oral S-adenosyl-L-methionine on hepatic glutathione in patients with liver diseasePMIDVendemiale G et al. · Scand J Gastroenterol · 1989
SAMe therapy resulted in a significant increase in hepatic glutathione levels in patients with both alcoholic and non-alcoholic liver diseases.
Reviews & position papers
4- 12Methionine as a double-edged sword in health and disease: Current perspective and future challengesPMIDParkhitko AA et al. · Free Radic Biol Med · 2021
Methionine restriction and supplementation both provide promising outcomes; its regulation is critical for maintaining health, but excess intake without B vitamins may cause hyperhomocysteinemia.
- 13Metabolic Consequences of Supplemented Methionine in a Clinical ContextPMIDGomez J et al. · Nutrients · 2020
Methionine is the precursor of homocysteine; deficient B vitamin intake or excessive methionine intake may result in hyperhomocysteinemia, a cardiovascular risk factor.
- 14Regulation of glutathione synthesisPMIDLu SC et al. · Mol Aspects Med · 2009
Up to half of the daily methionine intake is catabolized to SAMe in the liver; the transsulfuration pathway allows methionine to serve as a glutathione precursor.
- 15The role of methionine as an essential amino acid in human nutritionSource linkedPMIDBrosnan JT, Brosnan ME · J Nutr · 2006
Mechanistic & preclinical
1- 16Methionine and cysteine affect glutathione level, glutathione-related enzyme activities and the expression of glutathione S-transferase isozymes in rat hepatocytesPMIDShigesawa T et al. · J Nutr · 1997
Hepatocytes incubated with methionine showed increased intracellular glutathione with a twofold increase observed on day 6, supporting methionine's role in detoxification.
Common questions.
Quick answers about L-Methionine, drawn from the data on this page.
What is L-Methionine?
Essential sulfur-containing amino acid, precursor to SAMe and cysteine.
What is L-Methionine used for?
Commonly cited benefits of L-Methionine include: Methylation; Detoxification; Joint health; Hair/nail growth. NutriStack rates the overall evidence as moderate.
What is a typical dose of L-Methionine?
A typical adult dose of L-Methionine is 500-1,500 mg daily. The commonly recommended form is L-Methionine (free form). These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of L-Methionine?
Reported side effects include gi upset, elevated homocysteine without b6/b12/folate. This is educational information; check with a healthcare professional before use.
How strong is the evidence for L-Methionine?
NutriStack rates this as Moderate, meaning several aligned RCTs or one large RCT plus supporting reviews. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
Use this with your stack
L-Methionine in NutriStack.
Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.