L-Methionine: benefits, dosage, contraindications
Family or group:
Amino acids
Indications
Scoring methodology
EFSA approval.
Fetal development ✪✪✪✪✪
Methionine is essential for fetal development because of its involvement in homocysteine metabolism and the synthesis of S-adenosylmethionine (SAM), a methyl-group donor indispensable for DNA methylation and genetic regulation. These processes are particularly important during pregnancy to support the growth and development of organs in the fetus.nnEpidemiological research has shown that a high dietary intake of methionine during pregnancy is associated with a significant reduction in the risk of neural tube defects, such as spina bifida and anencephaly, compared with insufficient intake. These protective effects are reinforced by the interaction between methionine and other nutrients involved in homocysteine metabolism, such as folate, vitamin B12 and vitamin B6.nn
Posologie
Oral administration
19 mg/kg
Synergies
Breast cancer ✪✪✪✪✪
A meta-analysis suggested that a high dietary intake of methionine could reduce the risk of breast cancer by 6%, particularly in postmenopausal women, with an additional 4% reduction for each gram of methionine added daily. However, a more recent meta-analysis, including the large cohort (300,000 participants), found no significant association between methionine intake and breast cancer risk.
Posologie
Oral
19 mg/kg
Hair beauty ✪✪✪✪✪
Methionine, an essential amino acid, is a component of keratin, the main protein of hair. It plays a central role in hair growth and strength by supporting sulfur production, an important element for the structure of hair follicles. A randomized clinical study evaluated the efficacy of a supplement combining methionine, cysteine, taurine, iron, selenium, and marine collagen (300 mg per day) in people suffering from androgenetic alopecia or stress-related hair loss (telogen effluvium). After 12 weeks, subjects taking this supplement in addition to usual hair loss treatments (such as minoxidil) showed a significant improvement in hair density and thickness compared with treatments alone. These results confirm the value of methionine supplementation in promoting better hair health.
Posologie
Oral administration
19 mg/kg
Properties
Antioxidant
Methionine helps protect against oxidative stress by participating in the production of glutathione, a major antioxidant in the body. Glutathione neutralizes free radicals and protects cells from oxidative damage, which is involved in cellular aging and the development of many chronic diseases, including cancers and neurodegenerative diseases. nn
Anticancer
A high dietary intake of methionine is associated with a significant reduction in the risks of colorectal, breast, and pancreatic cancers. This benefit is linked to its role in the synthesis of S-adenosylmethionine (SAM), a methyl group donor essential for DNA methylation. This process protects DNA from mutations and promotes DNA repair.nnHowever, many tumors are dependent on exogenous methionine for their growth. This dependence, absent in normal cells, has led to the exploration of methionine restriction as a therapeutic strategy. Preliminary clinical trials have shown that dietary methionine restriction was safe and potentially effective in patients with advanced cancers, with encouraging results such as a 25% reduction in prostate-specific antigen (PSA) in one patient with prostate cancer after 12 weeks of the restrictive diet. nnFinally, in vitro studies show that methionine restriction activates pro-apoptotic pathways, such as the JNK1 kinase, leading to tumor cell death.nnThese data suggest a dual role for methionine: a key nutrient for cancer prevention via methylation and a potential therapeutic target to limit tumor growth in patients with certain cancers.nn
Usages associés
Hepatoprotective
Methionine is essential for liver health because of its role in detoxification and lipid metabolism. Increased glutathione production helps the liver neutralize toxins, including heavy metals. It also participates in the synthesis of lipoproteins, a factor in preventing hepatic steatosis.nnIn liver diseases, methionine promotes the regeneration of liver cells and reduces damage induced by toxic agents or an imbalanced diet.nn
Safe dosage
Adult: 19 mg/kg
The recommended dietary allowance (RDA) for methionine plus cysteine is 19 mg/kg/day.
Pregnant woman: 25 mg/kg
During pregnancy, the recommended intake is 25 mg/kg/day.
Lactating woman: 26 mg/kg
During lactation, the recommended intake is 26 mg/kg/day.
Child: 19 mg/kg - 59 mg/kg
Needs vary by age: - 0-6 months: 59 mg/kg/day - 7-12 months: 43 mg/kg/day - 1-3 years: 28 mg/kg/day - 4-8 years: 22 mg/kg/day - 9-13 years: 22 mg/kg/day (boys), 21 mg/kg/day (girls) - 14-18 years: 21 mg/kg/day (boys), 19 mg/kg/day (girls)
Contraindications
Hyperhomocysteinemia: contraindicated
Methionine is contraindicated in individuals with a specific genetic mutation called MTHFR C677T, which affects homocysteine metabolism. In these patients, taking methionine could increase homocysteine levels and raise the risk of vascular problems.
