Effect of l-arginine, asymmetric dimethylarginine, and symmetric dimethylarginine on ischemic heart disease risk: A Mendelian randomization study.

Background: l-arginine is a commonly consumed dietary conditional essential amino acid found in food items and supplements, which is closely related to asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). l-arginine is thought to increase nitric oxide and be cardioprotective, whereas ADMA and SDMA may inhibit nitric oxide synthesis and increase cardiovascular disease risk. Unexpectedly, l-arginine increased mortality in a small trial.