← All supplements
Limited evidenceGeneral health

L-Methionine

An essential amino acid central to methylation. There is no trial showing a benefit from supplementing it in healthy, protein-fed people, and loading doses measurably raise homocysteine.

Where to buy

View on iHerb

Ships to 180+ countries · welcome discount for new customers

Referral link — this site may earn a commission on purchases.

What the science says

  • Extra methionine raises homocysteine Moderate evidence

    Controlled human studies using oral methionine loading show that it acutely raises plasma homocysteine and transiently impairs endothelial function in healthy volunteers. This is the standard method for inducing experimental hyperhomocysteinaemia, which makes it an argument against casual supplementation rather than for it.

  • Antidote use, not supplement use Moderate evidence

    Oral methionine has a place in medicine as a second-line antidote in paracetamol overdose, covered in a Cochrane review of interventions for paracetamol poisoning, where intravenous acetylcysteine remains the preferred treatment. That clinical niche says nothing about taking methionine daily for liver support.

  • Methionine intake and metabolic health Limited evidence

    A review of sulfur amino acids and metabolic health notes that the experimental direction of interest is currently methionine restriction rather than supplementation, with human evidence still preliminary in both directions.

Dosage & safety

Studied doseNo supplementation dose is supported for healthy adults; the average Western diet already supplies roughly 2 g/day. Labels commonly suggest 500 mg/day. Clinical antidote use is a hospital protocol, not something to self-administer.
SafetyHigh intakes raise homocysteine, which matters for anyone with cardiovascular risk, and are a poor idea if B12, B6 or folate status is low. Avoid entirely in homocystinuria and in liver failure, where methionine loading can precipitate encephalopathy. Not for use in pregnancy without medical advice.

How to take it

TimingThere is no supported reason for a healthy adult to supplement methionine at all, so no timing applies.
With food?Take with food if you use it, to reduce nausea.
Worth knowingA normal Western diet already supplies roughly 2 g/day, so the question is usually whether to take it, not when.

Interactions

With other supplements

  • vitamin B12, B6 and folate

    These vitamins are what let your body clear the homocysteine that methionine loading generates; if status is low, the homocysteine rise is larger. do not take methionine if your B12, B6 or folate status is poor or untested

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Should you take L-methionine supplements?

There is no trial showing a benefit from L-methionine supplements in healthy, protein-fed people, and the average Western diet already supplies roughly 2 g/day. Extra methionine measurably raises homocysteine, which argues against casual use.

Does L-methionine raise homocysteine?

Yes, and the evidence is moderate: oral methionine loading acutely raises plasma homocysteine and transiently impairs endothelial function in healthy volunteers. The rise is larger if your B12, B6 or folate status is low.

Is L-methionine good for liver support?

No. Methionine is a second-line antidote in paracetamol overdose in hospital, but that says nothing about taking L-methionine daily for liver support, and it should be avoided entirely in liver failure.

Who should not take L-methionine?

Avoid L-methionine if you have cardiovascular risk, homocystinuria, liver failure, or low or untested B12, B6 or folate status. Do not use it in pregnancy without medical advice.

Scientific references

Related in General health