When Citrulline is consumed in combination with Arginine, the body is prevented from breaking down Arginine too quickly. As a result, this special amino acid synergizes with Arginine to increase nitric oxide (NOx) levels to more sustained levels allowing for longer duration of sexual performance. Clinical trials show that Citrulline supplementation improves erection hardness in men with mild ED. Moreover, Citrulline also increased the frequency of sexual intercourse per month by almost 20%.
M. Shirai et al., “Oral L-citrulline and Transresveratrol Supplementation Improves Erectile Function in Men With Phosphodiesterase 5 Inhibitors: A Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study,” Sex. Med., 2018.
L. Cormio et al., “Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction,” Urology, 2011.