- L-methionine PubChem
- List of foods high in methionine US Department of Agriculture
- Amino acid ChemPep
- Methionine uses, side effects WebMD
- Hypermethioninemia Genetics Home Reference
- Guttuso T et al, 2009, Effect of L-Methionine on Hot Flashes in Postmenopausal Women: A Randomized Controlled Trial PubMed Central
What is methionine?
Methionine abbreviation (symbol): Met
Methionine Functions in the Human Body
Methionine is :
- A building block of proteins
- S glucogenic amino acid — it can be converted into glucose 
- A source of sulfur
- A precursor of carnitine (a substance that helps to convert fats into energy)
- A substance that helps the liver to efficiently process fats
Methionine Rich Foods
- ANIMAL FOODS: beef, pork, poultry, fish, crabs, mollusks, cheese egg white 
- PLANT FOODS (>50 mg/1100 g food): whole grains, cornmeal, nuts, seeds 
Foods low in methionine: fruits, lentils, green leafy vegetables 
Hypermethioninemia is a rare hereditary (usually autosomal recessive) disorder with increased blood levels of methionine; it may occur together with other genetic metabolic disorders, such as homocystinuria, tyrosinemia and galactosemia . Symptoms and complications may include intellectual disabilities, delays in standing or walking, muscle weakness, unusual facial features and a boiled cabbage-smelling breath, sweat or urine .
Hypermethioninemia can also occur in infants fed with diets high in methionine .
Nonprescription (over-the-counter) L-methionine oral supplements are available.
There is INSUFFICIENT EVIDENCE about the effectiveness of L-methionine supplements in the prevention or treatment of alcoholism, allergies, asthma, colorectal cancer, Parkinson’s disease, radiation side effects, schizophrenia or drug withdrawal symptoms, or in improving liver function .
L-methionine supplements are POSSIBLY INEFFECTIVE in the prevention of hot flashes in menopausal women .
Methionine Safety: Side Effects, Toxicity
Methionine in recommended doses is POSSIBLY SAFE for most adults and children .
Side effects of methionine supplements may include nausea, vomiting and drowsiness . Allergic reaction to l-methionine are possible; symptoms may include itchy skin, rash, difficulty breathing, swelling of the face, lips, or tongue.
Not enough studies about safety of methionine supplements during pregnancy and breastfeeding have been performed, so women in these periods should better avoid them .
Who may need to avoid methionine?
Individuals with the following conditions may need to avoid methionine supplements or foods high in methionine :
- Homocystinuria, tyrosinemia and galactosemia
- Liver cirrhosis
- Methylenetetrahydrofolate reductase (MTHFR) deficiency