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L-methionine: the discovery

L-methionine is an essential amino acid that was discovered in 1921 by John Howard Mueller. Mueller, an American biochemist, isolated L-methionine from the milk protein casein. The discovery of this amino acid was groundbreaking, as it was one of the first isolated amino acids to be discovered that is not only of great importance for nutrition, but is also indispensable for numerous biochemical processes in the human body.

Dosage forms and dosage

It can be taken in a variety of forms. It is often sold as a dietary supplement in the form of tablets or capsules. It is also available in powder form, which allows for flexible dosing. The typical dosage for adults is 500 to 2000 mg per day, depending on the individual’s needs and medical advice. It is advisable to discuss the dosage with a doctor, especially if it is used to treat certain health conditions.

Diseases that L-methionine can cure

It has many health benefits and can help in the treatment of various diseases. Here are a few examples:

Liver disease

It plays a key role in sulfur metabolism and contributes to the formation of glutathione, an important antioxidant that protects the liver. In liver diseases such as fatty liver or cirrhosis, it can help to improve liver function and support detoxification.

Depression and anxiety

Methionine is a precursor for the synthesis of SAMe (S-adenosylmethionine), a molecule involved in the production of neurotransmitters such as serotonin and dopamine. A sufficient supply can help to alleviate depressive symptoms and stabilize mood.

Urinary tract infections

It can acidify urine, which inhibits the growth of bacteria and can be helpful in the treatment and prevention of urinary tract infections. This property makes it particularly valuable for people who are prone to recurrent urinary tract infections.

Wound healing

Methionine promotes collagen synthesis and the formation of new tissue, which can accelerate wound healing. It is therefore often used in the follow-up treatment of operations and injuries.

L-methionine: effect in the body

It is essential for the body because it supports various important functions:

  • Source of sulfur: As a sulfur-containing amino acid, methionine provides the sulfur needed for the synthesis of other important molecules such as cysteine and taurine.
  • Antioxidant effect: Methionine contributes to the formation of glutathione, one of the body’s most powerful antioxidants, which prevents cell damage caused by free radicals.
  • Protein biosynthesis: As an essential amino acid, methionine is needed for the production of proteins that are important for growth and repair processes in the body.

When to take it and how much

L-methionine should be taken if:

  • Deficiency symptoms due to insufficient intake through food
  • Increased physical or mental stress that increases the need for amino acids.
  • Certain health conditions such as liver disease, depression or urinary tract infections that may benefit from additional supplementation.

Contraindications and precautions

Not everyone should take it. People with:

  • Severe kidney disease should avoid methionine, as it can further impair kidney function.
  • Those with homocystinuria, a rare genetic disorder in which methionine is metabolized poorly, should not take methionine.

Dietary supplements and medicinal plants

The following dietary supplements can help to support the effect of L-methionine:

  • Vitamin B complex: vitamins B6, B12 and folic acid in particular are important for the methionine metabolism.
  • Antioxidants: supplements such as vitamins C and E can enhance the antioxidant effect of methionine.
  • Medicinal plants: Milk thistle can support liver function and, in combination with methionine, promote detoxification.

Foods rich in methionine

The main natural sources are:

  • Meat and fish: beef, chicken, pork and tuna are rich in methionine.
  • Eggs: egg yolks in particular contain high levels.
  • Dairy products: Cheese and milk also provide methionine.
  • Nuts and seeds: sesame, Brazil nuts and soybeans are good plant sources.

L-methionine: Possible side effects

In most cases it is safe, but occasionally side effects may occur, such as:

  • Nausea and digestive disorders.
  • Dizziness or headaches at high doses.

Overdose and its consequences

Overdosing can have serious consequences:

  • Hyperhomocysteinemia, an elevated level of homocysteine in the blood, which can increase the risk of cardiovascular disease.
  • Symptoms of poisoning such as confusion, nausea and, in the case of extremely high doses, even neurological disorders.

L-methionine in naturopathy

In naturopathy, it is often used to support liver health and promote detoxification. It is also a component of many protective and regenerative therapies, especially after surgery or in chronic diseases that require improved cell regeneration.

It is a remarkable amino acid with a wide range of applications and health benefits. By consciously integrating it into our diet and, if necessary, taking targeted supplements, it can make a valuable contribution to our health.

Important information on storage and shelf life

As with many dietary supplements, it is important to store it correctly to ensure its effectiveness. Store it in a cool, dry place, away from direct sunlight and moisture. Make sure that the packaging is tightly closed to prevent air from entering. Most methionine supplements can be stored for about two years if stored properly. Always check the expiry date on the packaging and dispose of expired products.

L-methionine and special diets

It can also play an important role in certain diets. For people who follow a vegan or vegetarian diet, it can be difficult to obtain sufficient amounts of methionine from plant sources alone. In such cases, supplementation can be useful to prevent deficiency symptoms.

Research and future developments

Scientific research on L-methionine is constantly progressing. Current studies are investigating the antitumor effect of methionine and its possible role in cancer therapy. There is evidence that methionine can influence tumor metabolism, which makes it an interesting target for new therapies. Other areas of research include the role of methionine in the aging process and its effects on longevity.


L-methionine is an essential amino acid with numerous health benefits. It plays a crucial role in sulfur metabolism, supports liver function, promotes wound healing and may help in the treatment of depression, urinary tract infections and other health problems.

However, it should be carefully dosed and preferably discussed with a doctor, especially if you have existing health problems or are taking other medications. Although it is generally well tolerated, side effects may occur in rare cases, and overdosing should be avoided to prevent serious health problems.

It is found in both animal and plant foods, with animal sources tending to contain higher amounts. For people with special dietary needs, such as vegetarians and vegans, supplementation may be necessary to ensure an adequate supply.

In naturopathy, methionine is valued for its detoxifying and regenerative properties and is often used to support liver health and cell regeneration.

As research progresses, our understanding of its diverse functions and potential therapeutic applications will continue to grow, making it an exciting topic in both medicine and nutrition.

Published on: 23. June 2024


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