L-Methionine
L-methionine is an essential sulfur-containing amino acid that has to come from food. The body uses it to make proteins, cysteine and SAMe.
What it is studied for
The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.
Why does the body need methionine?
Methionine is essential: the body needs a dietary supply. It also provides material for making cysteine. 1
A nutritional role is a starting point
A clinical review discusses methionine in protein metabolism and the rationale for studying it in nutrition aimed at preserving lean tissue. That biological rationale does not establish a benefit from extra methionine in well-nourished people. 2
Why people take it
SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.
Questions people ask
Does essential mean a supplement is necessary?
Essential means methionine must come from the diet. It does not mean that an isolated supplement is automatically needed. 1
Did the German study prove cardiovascular harm?
No. It measured a rise in homocysteine, not cardiovascular events. 3
Is 210 mg a recommended daily nutrient intake?
No. It is VKM’s tentative guidance for supplemental methionine, based on a safety assessment. 4
Lysine
L-Threonine
L-Cysteine
Leucine