Taking 6 grams of L-arginine might help healthy young men lower their blood pressure and increase a chemical in their blood that helps blood vessels relax.

A double-blind, placebo-controlled RCT in healthy young men aged 19–38 years, where participants receive either 6 g of L-arginine or a placebo daily for 4–8 weeks, with plasma nitrite levels and systolic blood pressure measured at baseline, 2 weeks, and 4–8 weeks.

A crossover RCT in the same population where each participant receives both 6 g L-arginine and placebo in randomized order, separated by a 2-week washout, with plasma nitrite and systolic BP measured after each phase to assess within-subject changes.

A prospective cohort study tracking healthy young men taking 6 g L-arginine daily over 6 weeks, measuring plasma nitrite and systolic BP at baseline and weekly to observe temporal associations without randomization.

A case series reporting plasma nitrite and systolic BP changes in a small group of healthy young men (n=10–15) who took 6 g L-arginine daily for 4–6 weeks, with pre- and post-intervention measurements.

An in vitro study using human endothelial cells exposed to 6 g/L L-arginine (equivalent to plasma concentration after 6 g oral dose) to measure nitric oxide production and nitrite accumulation, supporting the proposed mechanism.