L-Methionine

Essential sulfur-containing amino acid crucial for methylation, detoxification, and antioxidant production

Scientific nameL-Methionine FormulaC5H11NO2S Molecular weight149.21 g/mol CAS63-68-3

85 absorption score

6 safety / 10

25 USD per month

5 documented interactions

Check it against something

Evidence level B

L-Methionine with:

78 out of 100

Works better together Compatible. Timing differs, so follow each supplement's own window.

Check it against your whole stack →

What it does

mechanism and evidence for each claim

Enhanced detoxification

Supports liver detoxification and toxin elimination

Precursor to glutathione and other detoxification compounds Evidence A-grade 2-4 weeks

Improved methylation support

Essential for methylation reactions and gene expression

Converted to SAM-e for methylation processes Evidence A-grade 1-4 weeks

Antioxidant production

Critical for glutathione synthesis and antioxidant protection

Provides sulfur for glutathione and other antioxidants Evidence A-grade 2-6 weeks

Liver health support

Protects liver from damage and supports healthy function

Prevents fatty liver and supports hepatic metabolism Evidence B-grade 4-12 weeks

Hair and nail health

Supports healthy hair growth and nail strength

Provides sulfur for keratin and structural proteins Evidence B-grade 6-16 weeks

Others take these for the same thing

Same goal, different mechanism — check any of them against this one

Turmeric Anti-inflammatory & antioxidant 300-1000mg A 3% Glutathione Master antioxidant & detox support 250-750mg B 20% Astaxanthin Superior antioxidant & skin protection 4-12mg B 20% SAM-e Mood support & liver health 400-800mg A 70% Plant Collagen Vegan collagen support & antioxidants 2-5g C 70% Quercetin Immune support & allergy relief 500-1000mg B 5%

Every pair we checked

12 combinations scored by the engine

L-Methionine + Caffeine No documented interaction either way No known interaction 70

L-Methionine + Creatine Monohydrate No documented interaction either way No known interaction 70

L-Methionine + Vitamin D3 No documented interaction either way No known interaction 70

L-Methionine + Calcium Carbonate No documented interaction either way No known interaction 70

L-Methionine + Whey Protein No documented interaction either way No known interaction 70

L-Methionine + Lactase No documented interaction either way No known interaction 70

L-Methionine + Bovine Collagen No documented interaction either way No known interaction 70

L-Methionine + DHA No documented interaction either way No known interaction 70

L-Methionine + Turmeric No documented interaction either way No known interaction 70

L-Methionine + Fish Oil (EPA/DHA) No documented interaction either way No known interaction 70

L-Methionine + Glycine Helps with methionine detoxification Works better together 78

L-Methionine + Betaine HCl Alternative methyl donor to support methionine Works better together 78

Dosage

With food

Daily500-1500mg

Maintenance200-500mg daily

Therapeutic500-1500mg daily

Liver support1-2g daily (with monitoring)

Upper limit3g daily (requires B vitamin cofactors)

Before you take it

VeganYes

When to expect it

First Effects1-2 weeks for methylation and detoxification benefits

Peak Benefits6-12 weeks for liver health and antioxidant benefits

Deficiency DevelopmentWeeks to months with inadequate protein intake

Toxicity OnsetWeeks with very high doses and inadequate B vitamins

How to measure it

$80-200

MarkerPlasma methionine, homocysteine, or SAM/SAH ratio

OptimalMethionine: 20-40 μmol/L, Homocysteine: <10 μmol/L

Deficient belowMethionine: <15 μmol/L

FrequencyEvery 3-6 months if supplementing or monitoring methylation

What people actually reported to the FDA

CAERS, 0 reports naming it as the suspect

Named as the suspect 0 reports of 2 that mention it at all

Reports are voluntary and unverified — they record what someone experienced while taking something, not what the compound caused. Counts skew towards products people take a lot of, and a serious outcome is more likely to be reported than a mild one, so these are not rates. How we filter them →

What actually reaches you

The label counts the carrier, your body does not

Absorption Very high 85 of 100 · best absorbed form of this compound

Delivered daily 850 mg

Cost per 100 mg delivered $0.10 comparative — uses the absorption score, not a measured percentage

Works better with

3 documented

Folate B12 B6

B vitamins essential for safe methionine metabolism

Required for homocysteine detoxification and methylation · level A

Glycine

Helps with methionine detoxification

Supports phase II liver detoxification · level B

Betaine

Alternative methyl donor to support methionine

Provides methyl groups for methylation reactions · level B

What not to take with L-Methionine

2 documented

Alcohol

Alcohol depletes methionine and increases requirements

Interferes with methionine metabolism and methylation · major significance

High Protein Excess

Excessive protein may increase methionine load

Can overwhelm methylation capacity · moderate significance

Medication interactions

Discuss these with a pharmacist before combining

levodopa Moderate

Methionine may reduce levodopa effectiveness

What to do: Monitor Parkinson's symptoms and medication effectiveness

5-fluorouracil Major

May interfere with chemotherapy effectiveness

What to do: Avoid during chemotherapy

Available forms

bioavailability compared

L-Methionine (Free Form) 85

L-Methionine (Free Form): Essential for methylation, Liver detox support, Antioxidant precursor, Well-researched

Food sources

before you supplement

Meat and poultry 0.6-1.0g per 100g · 85

Fish and seafood 0.5-0.8g per 100g · 85

Eggs 0.4g per 100g · 90

Dairy products 0.3-0.6g per 100g · 80

Too little

deficiency signs

Fatty liver and impaired liver function
Poor detoxification capacity
Reduced glutathione levels
Hair loss and poor hair quality
Brittle nails and skin problems
Impaired immune function
Poor growth and development

Too much

toxicity signs

Elevated homocysteine levels
Increased cardiovascular risk
Gastrointestinal upset
Potential atherosclerosis
Requires B vitamin cofactors to prevent toxicity

Who benefits most

liver-detox-support

Essential for liver detoxification and glutathione production

500-1500mg daily

methylation-support

Critical for proper methylation and gene expression

500-1000mg daily (with B vitamins)

antioxidant-support

Essential for glutathione and antioxidant synthesis

500-1500mg daily

hair-nail-health

Provides sulfur for keratin and structural proteins

500-1000mg daily

fatty-liver-prevention

Helps prevent and address fatty liver conditions

500-1500mg daily

Where to buy it

compare forms first

Look for L-Methionine at 500-1500mg per serving. The form that matters here is L-Methionine (Free Form).

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What else affects it

Beyond other supplements

Alcohol

Alcohol depletes methionine and increases requirements

Interferes with methionine metabolism and methylation

How it works

Converted to S-adenosyl-methionine (SAM-e) for methylation
Precursor to glutathione for antioxidant protection
Essential for phosphatidylcholine synthesis
Required for creatine and carnitine production
Important for DNA methylation and gene expression
Supports liver detoxification enzyme function

Key findings

what the evidence supports

Essential for methylation reactions and gene expression
Critical for glutathione synthesis and antioxidant protection
Important for liver health and detoxification
Must be balanced with B vitamins to prevent homocysteine elevation

Sources: NIH Examine.com · data reviewed 2026-08-02

Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →

Common questions

What are the benefits of L-Methionine?

Documented effects: Enhanced detoxification; Improved methylation support; Antioxidant production; Liver health support. Supports liver detoxification and toxin elimination

How much L-Methionine should you take per day?

The common daily range is 500-1500mg. By goal — maintenance: 200-500mg daily; therapeutic: 500-1500mg daily; liver support: 1-2g daily (with monitoring); upper limit: 3g daily (requires B vitamin cofactors).

When is the best time to take L-Methionine?

With food. First effects are typically reported within 1-2 weeks for methylation and detoxification benefits.

What are the side effects of L-Methionine?

At excessive doses: Elevated homocysteine levels, Increased cardiovascular risk, Gastrointestinal upset, Potential atherosclerosis, Requires B vitamin cofactors to prevent toxicity. Safety rating at normal doses is 6 out of 10.

What should you not take with L-Methionine?

Separate it from Alcohol, High Protein Excess by two to four hours. Alcohol depletes methionine and increases requirements

Does L-Methionine interact with medications?

Documented interactions with levodopa, 5-fluorouracil. Discuss these with a pharmacist before combining.

How do you know if you need L-Methionine?

The marker is Plasma methionine, homocysteine, or SAM/SAH ratio, optimal range Methionine: 20-40 μmol/L, Homocysteine: <10 μmol/L. Common deficiency signs: Fatty liver and impaired liver function, Poor detoxification capacity, Reduced glutathione levels, Hair loss and poor hair quality.

Taken for

49 Liver & Detox

Turmeric · Vitamin C (Ascorbic Acid) · D-Mannose