Methionine — is an essential amino acid involved in protein synthesis, detoxification, regulation of metabolism, and protection of cells from oxidative stress. It is necessary for the formation of other amino acids, such as cysteine, as well as for the synthesis of creatine, taurine, and glutathione.
Methionine plays an important role in methylation — a process that regulates gene expression and liver function.
A deficiency or excess of this nutrient can affect the functions of the immune, nervous, and cardiovascular systems.
Beneficial Properties
- involved in the synthesis of proteins, taurine, creatine, and other compounds;
- helps eliminate toxins and supports liver function;
- has antioxidant properties due to its involvement in glutathione synthesis;
- regulates fat metabolism and cholesterol levels;
- provides sulfur for the construction of other amino acids, including cysteine.
Daily Requirement and Sources
The average daily intake of methionine for an adult is about 13 mg per kilogram of body weight, which is equivalent to 900–1000 mg per day for a weight of 70 kg.
The requirement may increase with high physical activity, pregnancy, or liver diseases.
Foods rich in methionine:
- meat — beef, chicken, pork;
- fish — tuna, salmon;
- eggs;
- dairy products — cheese, yogurt, cottage cheese;
- nuts and seeds — sesame, sunflower, cashews.
Possible forms and their learnability
Nutrient forms are listed from best to worst:
| Product | Price, $ |
|---|---|
Nutricology, L-Methionine, 500 mg , 100 Vegetarian Capsules | 23.26 |
NOW Foods, L-Methionine, 500 mg, 100 Capsules | 16.04 |
Source Naturals, SAMe S-Adenosyl-L-Methionine, 200 mg, 60 Enteric Coated Tablets | 30.79 |
Swanson, L-Methionine, Featuring AjiPure, 500 mg, 60 Veggie Caps | 10.86 |
Swanson, L-Methionine, 500 mg, 30 Capsules | 3.54 |
Symptoms and Consequences of Deficiency
- increased toxin levels and impaired liver function;
- weakened immune system and reduced resistance to infections;
- mental and physical fatigue, decreased concentration;
- disruptions in lipid metabolism and increased cholesterol levels;
- decreased synthesis of creatine and glutathione.
Chronic deficiency may manifest as metabolic disorders, reduced cognitive functions, and the development of liver diseases.
Possible Risks of Excess and Their Manifestations
- increased homocysteine levels — a risk factor for cardiovascular diseases;
- stress on the liver and possible development of fatty degeneration;
- anxiety, irritability, and disruptions in neurotransmitter balance;
- allergic reactions: itching, rash, swelling;
- exacerbation of chronic diseases, including oncological risks.
For most people, excess methionine is only possible with excessive consumption of protein supplements.
A safe dose is considered to be up to 3 g per day, but exceeding this norm requires monitoring by a specialist.