What is Methionine?
Methionine is an amino acid. Amino acids are the building blocks that our bodies use to make proteins. Methionine is found in meat, fish and dairy products and it plays an important role in many functions within the body.
One of the unique features of methionine is the ability to be converted into important sulfur-containing molecules. These molecules have a variety of functions, including the protection of your tissues, modifying your DNA and maintaining proper functioning of your cells.
These important molecules must be made from amino acids that contain sulfur. Of the amino acids used to make proteins in the body, only methionine and cysteine contain sulfur. Although your body can produce the amino acid cysteine on its own, methionine must come from your diet.
Other Roles in Cell Function
One of its major roles in the body is that it can be used to produce other important molecules. It is involved in the production of cysteine, the other sulfur-containing amino acid used to build proteins in the body.
Cysteine can create a variety of molecules, including proteins, glutathione and taurine. Glutathione is sometimes called the master antioxidant due to its critical role in the defenses of your body. It also plays a role in the metabolism of other nutrients and production of DNA.
Another important molecule that methionine can be converted to is S-adenosylmethionine (SAM), which is used to produce creatine, a very important molecule for cellular energy.
Food Sources of Methionine
Eggs, fish and some meats contain high amounts of this amino acid. It is estimated that around 8% of the amino acids in egg whites are sulfur-containing amino acids (methionine and cysteine).
This value is about 5% in chicken and beef and 4% in dairy products. The highest content (6.8 grams per day) was reported in high-protein diets, while lower intakes were present for vegetarians (3.0 grams per day) and vegans (2.3 grams per day).
Effects on Different Conditions
Studies have shown that methionine is effective in the treatment of acetaminophen (tylenol) poisoning. Research shows that taking methionine by mouth seems to be effective treating this condition. Treatment should begin as quickly as possible but must start within 10 hours of the overdose. Some other conditions it which it has show some level of evidence are:
- Breast cancer. Eating higher amounts of methionine may be linked to a lower risk of breast cancer.
- Colon cancer. Eating a diet rich in methionine and folate, a type of B vitamin, seems to help reduce the chance of colon cancer. This seems to be especially true for people with a family history of colon cancer and people who drink large amounts of alcohol.
- Parkinson ‘s disease. Early research suggests that taking L-methionine by mouth for up to 6 months improves symptoms of Parkinson’s disease, such as tremor, inability to control movements and rigidity.
The daily recommended intake of methionine plus cysteine is 8.6 mg/lb (18 mg/kg) per day in adults, which is around 1.3 grams for someone weighing 150 pounds.
Clinical research study results do not point to serious signs of toxicity, except at very high doses of methionine. Daily doses of 250 milligrams (mg), which is approximately 25% of the recommended daily dose of methionine, are reportedly safe.
Grant Tinsley, PhD. (2018, Apr 13) Methionine: Functions, Food Sources and Side Effects. Healthline. Retrieved from: https://www.healthline.com/nutrition/methionine