Background

• Methionine is one of nine essential amino acids, so called because they cannot be made by the human body and must be obtained through the diet. Sources of methionine include protein-rich foods such as beef, chicken, fish, liver, pork, cottage cheese, eggs, lentils, pumpkin seeds, sesame seeds, sunflower seeds, and yogurt.
• Supplementary L-methionine has been used to treat symptoms of Parkinson's disease, insomnia, and severe acetaminophen (e.g., Tylenol®) poisoning. In addition, increased dietary intake of methionine has been shown to reduce the risk of a specific type of brain and spinal cord birth defect known as neural tube defects (NTDs). More well-designed human studies are needed to determine if methionine is safe and effective for treating any medical condition.
• Very high doses of supplementary methionine have been shown to increase levels of the amino acid homocysteine. High homocysteine levels are a risk factor for heart disease. Some studies have suggested links between methionine and cancer, but more research is needed before firm conclusions can be made.

References

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