Methionine is an essential amino acid that is necessary for the human body to function properly. This particular amino acid cannot be synthesized by the body, so it must be obtained through dietary intake only.
Methionine may be consumed from various food sources, and it is also available in the form of a supplement. Methionine benefits are purported to include support for liver health, antioxidant effects, improved collagen synthesis, immune system support and mood support.
According to the Natural Medicines Database, this supplement may be used for a variety of different purposes, ranging from schizophrenia to liver problems. L-Methionine is also used as a chelator for detoxification and is taken by bodybuilders to support athletic performance and muscle growth.
Although the United States Food and Drug Administration has not approved methionine for the treatment of any medical ailment, some research studies have indicated that methionine may be effective for certain purposes. Below is some additional information about methionine benefits, uses and side effects.



- Used to make the anti-oxidant glutathione
- Supports detoxification pathways
- Can be converted into SAMe
What does L-Methionine Do for the Body?
In the human body, L-Methionine is responsible for building various protein molecules, as well as the synthesis of L-cysteine, another amino acid.
It plays a role in translation of m-RNA, has been shown to increase glutathione, homocysteine, and taurine levels and supports the absorption of selenium and zinc.
L-methionine also acts as an antioxidant, helping to protect against the damaging effects of free radical particles. It has been used as an anti-aging supplement for this reason.
Methionine is also used to make S-Adenosyl-L-methionine (SAM-e), which is a natural compound that acts as a precursor to important neurotransmitters in the brain. SAM-e is considered effective for reducing depression symptoms and is also used to improve joint functionality and alleviate pain.
Research studies have shown that methionine may have several beneficial effects on the body. For example, some studies have indicated that methionine may reduce the risk of pancreatic cancer.
However, other studies found that depleting methionine may be beneficial to patients with metastatic cancer. Further research is needed to determine the exact effect methionine has on the development of cancerous tumors, as well as the progression of existing cancers.
Methionine Benefits and Uses
The purported benefits of Methionine as a dietary supplement have not been well-researched. We know a lot about the role of this amino acid in the body, but there has been limited research into the effects and benefits of administering exogenous L-Methionine dietary supplements.
The Natural Medicines Database reports that methionine has been used for the following purposes.
- Testing for hyperhomocysteinemia
- Preventing liver damage from acetaminophen poisoning
- Parkinson’s disease
- Drug withdrawal
- Schizophrenia
- Radiation side effects
- Copper toxicity
- Asthma
- Allergies
- Alcoholism
- Depression
Some research has shown that methionine benefits may be effective for the treatment of acetaminophen poisoning. However, further research is needed to verify these findings.
Studies have not yet been able to conclude whether methionine may be effective for the other purposes on this list, but research is ongoing. The FDA has not approved methionine as a drug for the treatment or prevention of any medical conditions.
Methionine Benefits for Bodybuilding
Because of methionine’s role in the production of proteins, some bodybuilders take this amino acid in supplement form in hopes of increasing muscle mass.
L-Methionine is required for the synthesis of new proteins. It is the universal N-terminal amino acid in growing peptide chains, which means that it is found at the end of growing protein molecules.
If you are deficient in L-Methionine, this could impair the synthesis of new protein strands, which could impair muscle growth and recovery following a workout. However, there have not been studies showing that increased consumption of Methionine can increase muscle protein synthesis.
Many bodybuilding websites recommend consuming a minimum of 1 gram of protein per pound of lean muscle mass. If you are below this level, you may be at risk of a Methionine deficiency.
At this time, research on this topic is limited and clear conclusions cannot be drawn. However, researchers are continuing to explore the relationship between methionine and muscle mass.
Recommended Methionine Dosage
Because of the risks associated with higher doses of methionine, it is important to take the proper dosage at all times. The FDA has not approved methionine as a medical treatment, so no standardized dosing guidelines are available.
The recommendations below are based on the dosages that have been used in past clinical studies, according to the Natural Medicines Database.
- Parkinson’s disease – 5 grams of methionine daily for two weeks to six months.
- Insomnia – 500 mg of methionine just before bedtime.
- Acetaminophen toxicity – 2.5 grams of methionine at four hour intervals within 10 hours of acetaminophen ingestion.
Because methionine is an essential amino acid that cannot be produced by the body, all people must consume a certain amount of methionine from foods that we eat.
The dietary reference intake recommendation for cysteine and methionine combined is 25 mg per gram of protein. According to the Natural Medicines Database, dosages of more than 100 mg per kg of body weight should be avoided, as doses of this size may cause severe and potentially fatal cerebral effects.
Methionine Side Effects
The Natural Medicines Database reports that methionine supplementation is considered possibly safe for both children and adults when used appropriately in intravenous or oral form.
However, larger doses of this supplement may not be safe for consumers. According to WebMD, some of the adverse effects of high doses of methionine may include:
- Increased tumor growth
- Increased blood levels of homocysteine, which may raise the risk of cardiovascular problems
- Brain damage
- Death in extreme cases
Women who are pregnant or nursing should avoid methionine supplementation, as it is not known whether the supplement is safe for members of these populations.
Taking Methionine Safely
Because of the purported L-methionine health benefits of methionine, some people choose to take supplements of this amino acid in addition to the amount they consume in food.
However, because of the potentially dangerous methionine effects that may occur with higher dosages of this supplement, exercising caution when taking this supplement is highly recommended.
If you plan to take methionine as a supplement, talk to your doctor before you begin a regimen. Begin with a low dosage and gradually increase the amount you take until you achieve the desired methionine benefits.
Never take more methionine than your doctor recommends, and follow the instructions on the supplement’s label carefully. Do not take methionine for longer than you need to.
If you experience any significant side effects while taking methionine, discontinue your use of the supplement and talk to your doctor. If you think you may have taken too much methionine, seek medical treatment as soon as possible.
Article last updated on: March 12th, 2018 by Nootriment