L-Methionine
Compiled from published pharmacological and botanical literature. Not independently verified by Herbuno. Spotted an error or have a correction? Flag it below →
| Compound | L-Methionine |
|---|---|
| Chemical class | Essential sulphur-containing α-amino acid — thioether side chain |
| CAS | 63-68-3 (L-methionine) · 59-51-8 (DL-methionine) |
| Primary source | Chemical synthesis for DL- grades; fermentation or enzymatic resolution for L- grades |
| Key applications | Methylation via SAMe, protein synthesis initiation, cysteine and taurine precursor, lipotropic |
| Claim strength | High for essentiality and methylation biochemistry; low and cautioned for supplementation |
| Typical form | Crystalline L-methionine or racemic DL-methionine at 99% |
| Buy from Herbuno | L-Methionine Powder · DL-Methionine 99% Powder |
| Origin | Processed / Sourced from India |
| MOQ | R&D 100 g / 250 g (subject to stock) · Pilot batch 1–5 kg · Bulk 10 kg, 25 kg and above |
| Lead Time | Dispatch within 72 hrs from stock · fresh-batch production (typically 50 kg+): 10 working days |
| Documentation | CoA & MSDS standard with every lot |
Name origin: From its chemistry — a methyl group attached to sulphur, meth plus thio, plus the amino acid ending. John Howard Mueller isolated it in 1922 from casein. That methyl-sulphur arrangement is the entire basis of its biological importance: methionine is the body's principal methyl donor, and the thioether sulphur is what makes the donation chemistry work.
Discovery and production history: Methionine occupies a special position in protein synthesis: it is the initiator amino acid, so every protein begins its translation with methionine, which is often removed afterwards. Industrially, methionine is the largest-volume amino acid after glutamate, produced overwhelmingly for poultry feed, where it is the first limiting amino acid. Production is dominated by chemical synthesis from acrolein and methyl mercaptan, which yields the racemic DL- mixture; L-specific routes by fermentation or enzymatic resolution command a substantial premium.
Research trajectory: Methionine's research profile is unusual in running strongly in both directions. On one side, methionine is the precursor of S-adenosylmethionine, the universal methyl donor for DNA, protein and neurotransmitter methylation, and SAMe itself has a clinical literature in depression and osteoarthritis. On the other, methionine catabolism generates homocysteine, and methionine restriction has become one of the more robustly reproduced interventions in ageing research, extending lifespan across multiple species. Few nutrients carry such clearly opposed literatures.
Commercial source: DL-methionine from chemical synthesis is the high-volume grade. Unusually among amino acids, the D- form is not biologically useless here: D-methionine is converted to L-methionine in the liver and kidney by a two-step oxidation and transamination, so DL-methionine has substantial nutritional value, which is why the racemate is acceptable in feed and in some food applications. L-methionine from fermentation or resolution is specified where the conversion step is undesirable or where label requirements demand it.
Evidence for L-Methionine Applications
The methylation role is foundational biochemistry and the most defensible thing to say about methionine. Methionine is adenosylated to S-adenosylmethionine, which donates methyl groups to DNA, histones, phospholipids, creatine synthesis and neurotransmitter metabolism, before becoming S-adenosylhomocysteine and then homocysteine. This cycle is central to epigenetic regulation and to one-carbon metabolism. It is also precisely why supplementing methionine is not straightforward: pushing substrate into the cycle pushes product out the other end. Claim strength: High.
Homocysteine generation is the constraint that limits methionine dosing, and it should be stated prominently rather than buried. Methionine loading is used clinically as a diagnostic challenge precisely because it raises plasma homocysteine sharply and reproducibly. Elevated homocysteine is associated with cardiovascular and cognitive risk in observational data. Supplementing methionine at meaningful doses therefore raises a marker that most of the supplement industry simultaneously sells B vitamins to lower. Adequate folate, B12 and B6 are required to recycle homocysteine back to methionine, and a methionine product without them is poorly conceived. Claim strength: High.
Methionine restriction extends lifespan in animal models, which is the opposite of a supplementation case. Dietary methionine restriction has reproducibly extended lifespan in rodents and other model organisms and improves several metabolic parameters, and it is one of the better-replicated interventions in the ageing literature. The mechanisms are debated and human data are limited. This does not mean methionine is harmful at dietary levels, but it does mean the ageing and longevity narrative in supplements points away from methionine supplementation rather than toward it. Claim strength: Moderate.
As the limiting amino acid in legume proteins, methionine has a genuine fortification application that mirrors lysine's in cereals. Legumes — soy, pea, chickpea, lentil — are relatively low in methionine, while cereals are relatively low in lysine, which is the biochemical basis for the traditional complementary pairing of pulses with grains across many cuisines. For a formulator building a pea or soy protein product, methionine is the correction that raises the amino acid score, exactly as lysine is for rice or wheat protein. Claim strength: High.
SAMe has its own clinical evidence that methionine cannot borrow. SAMe supplementation has shown efficacy in depression comparable to some conventional agents in several trials and has been used for osteoarthritis. Methionine is its precursor, but converting methionine to SAMe requires ATP and is regulated, so supplementing methionine does not reliably raise SAMe to the levels the SAMe trials used. A methionine product positioned on SAMe's mood data is making a claim its ingredient does not support. Claim strength: High for the distinction.
Safety at dietary levels is unproblematic; at high supplemental doses it is less clear. Acute high doses cause nausea and the homocysteine rise described above. There is no established tolerable upper intake level. Methionine supplementation is contraindicated in homocystinuria, an inherited disorder of methionine metabolism, and should be approached with caution in anyone with existing hyperhomocysteinaemia or compromised B vitamin status. The sulphurous odour is also a practical consideration at supplemental doses. Claim strength: Moderate.
Sourcing methionine from Herbuno. We supply L-methionine and DL-methionine. Unusually for an amino acid, the racemate is nutritionally useful here, since D-methionine is converted to the L- form in vivo — so DL- is a legitimate choice rather than a compromise in many applications.
If you are formulating methionine at supplemental rather than protein-fortification levels, plan the folate, B12 and B6 alongside it so the homocysteine generated can be recycled. All lots ship with CoA and MSDS as standard; request a quotation for pilot or bulk volumes.
Dosage & Formulator Specification
Both L- and DL- grades are dosed as the free amino acid at 99%. Adult requirement for methionine plus cysteine combined is around 19 milligrams per kilogram daily, since cysteine can be synthesised from methionine and spares it. Supplemental doses in the literature vary widely and there is no consensus figure, which reflects the absence of a clear supplementation indication. For protein fortification the inclusion is calculated against the base protein's amino acid profile, as with lysine, and is typically in the range of 1 to 2% of protein weight for a legume base.
The L- versus DL- decision is genuinely different here from other amino acids. D-methionine is converted to L-methionine in liver and kidney, so DL- carries real nutritional value — unlike D-arginine or D-lysine, which are essentially inert. DL- is substantially cheaper and is the standard in feed and in many food applications. Specify L- where the conversion step is undesirable, where a label requires it, or where the application is clinical. Do not assume DL- is a lower-grade substitute, and equally do not assume the conversion is complete or instantaneous.
Formulation handling is dominated by odour. Methionine carries a pronounced sulphurous, cabbage-like note that intensifies with heat and on oxidation, and it is difficult to mask at the doses used in supplementation. Capsules are the usual answer. Methionine is moderately soluble in water, stable across a reasonable pH range, and participates in Maillard reactions with reducing sugars. In thermally processed products containing sugars, the combination of browning and sulphurous volatiles can be particularly objectionable, so compatibility testing in the finished matrix is advisable rather than optional.
For analytical control, specify the isomeric form explicitly and require optical rotation or a chiral method to confirm it, since L- and DL- cannot be distinguished by a standard assay and the price difference creates a substitution incentive. Standard amino acid specifications cover heavy metals, residual solvents, microbiological limits and loss on drying. For synthetic material, require residual acrolein and methyl mercaptan derivatives as specified impurities. Methionine is synthetic or fermentation-derived rather than plant-extracted, so phytosanitary certification does not apply.
The co-formulation decision is where most methionine products are won or lost. Because methionine catabolism generates homocysteine stoichiometrically, a methionine product at supplemental doses should carry the methyl-cycle cofactors that recycle it: folate, B12 and B6, with riboflavin and betaine as reasonable additions since betaine provides an alternative homocysteine remethylation route independent of folate status. The alternative design decision is to keep methionine out of the supplemental-dose range entirely and use it only as a protein fortificant, where the inclusion is calculated against the base protein's amino acid profile and total intake stays within dietary bounds. Both are defensible; what is not defensible is a standalone high-dose methionine product with no cofactor provision, which raises a biomarker the rest of the category sells products to lower.
Market positioning should also account for the restriction literature, which is unusual in pointing away from the ingredient. Dietary methionine restriction is among the better-replicated lifespan interventions in model organisms, and that body of work is increasingly cited in consumer-facing longevity content. A formulator building in the healthy-ageing space should know that methionine supplementation sits awkwardly against that narrative, and that the defensible applications are elsewhere: correcting the limiting amino acid in legume protein isolates, clinical nutrition where methionine intake is genuinely inadequate, and lipotropic formulations where the methyl-donor function rather than the amino acid content is the rationale. Those are real applications with real specifications behind them, which is a better commercial footing than a claim the literature contests.
Frequently Asked Questions — L-Methionine
Is DL-methionine inferior to L-methionine?
Not in the way it is for most amino acids. D-methionine is converted to L-methionine in liver and kidney, so the racemate carries real nutritional value — unlike D-arginine or D-lysine, which are essentially inert. DL- is substantially cheaper and standard in feed and many food applications. Specify L- where the conversion step is undesirable or a label requires it.
Does methionine raise homocysteine?
Yes, sharply and reproducibly — methionine loading is used clinically as a diagnostic challenge for exactly that reason. Elevated homocysteine is associated with cardiovascular and cognitive risk observationally. If you formulate methionine at supplemental doses, plan folate, B12 and B6 alongside it so the homocysteine can be recycled. A methionine product without them is poorly conceived.
Can a methionine product claim SAMe's benefits?
No. SAMe has its own trial evidence in depression and osteoarthritis, but converting methionine to SAMe requires ATP and is regulated, so supplementing the precursor does not reliably reach the SAMe levels those trials used. Positioning methionine on SAMe's mood data is claiming something the ingredient does not deliver.
Why fortify a pea or soy protein with methionine?
Because methionine is the limiting amino acid in legume proteins, exactly as lysine is in cereals — which is the biochemistry behind the traditional pairing of pulses with grains. For a pea or soy base, methionine is the correction that raises the amino acid score. Calculate against the isolate's actual profile, typically 1 to 2% of protein weight.
Will it smell?
Yes, pronounced sulphurous and cabbage-like, intensifying with heat and oxidation, and difficult to mask at supplemental doses. Capsules are the usual answer. In thermally processed products containing sugars the combination of Maillard browning and sulphurous volatiles can be particularly objectionable — test in the finished matrix.
Why source methionine from India?
Around 80% of raw nutraceutical ingredients originate in China and a second qualified origin is increasingly a continuity requirement. Methionine is the largest-volume amino acid after glutamate because of feed demand, so capacity is well established, and India has both synthetic and fermentation routes available.