These results from a clinical study published by the International Society for Sexual Medicine demonstrate that the combination of citrulline and resveratrol are effective at reducing symptoms of ED. In this study, 20 patients ages 29-78 were given these ingredients found in Alpha Male Plus (or placebo) for 4 weeks and then followed up with a standard sexual health questionnaire, the Sexual Health Inventory for Men. Citrulline and resveratrol improved erection firmness, erection confidence, intercourse satisfaction and total score. The SHIM score questionnaire has been shown to be simple, reliable, and valid for the assessment of erectile function in clinical trials , .
In pre-clinical experiments, citrulline improved intracavernous pressure and arterial pressure (ICP/MAP), smooth muscle/collagen ratios, and serum levels of NOx in patients with vascular-related ED and low-testosterone ED .Although few experiments have been performed on humans, one recent clinical study showed that oral L-citrulline supplementation improves the Erection Hardness Score (EHS) without adverse events in men with mild ED .
Previous studies have shown that resveratrol treatment leads to SIRT1 activation, and subsequently increased NOx leads to enhancement of cGMP synthesis via the NO/cGMP pathway that is responsible for maintaining an erection . Resveratrol also causes an increase in firmness of the corpus cavernosum and an increase in blood testosterone levels .
Excitingly, this new clinical study combines those earlier insights and shows that citrulline and resveratrol have a synergistic effect on helping to improve erectile function and overall intercourse satisfaction.
Data adapted from Shirai M, Hiramatsu I, Aoki Y, et al. Sex Med 2018; 6:291-296.
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