Functionality of Supplements and Anti-aging: Functionality of Supplements—Male Medical

Phosphodiesterase (PDE) 5 inhibitors maintain erectile ability by increasing the concentration of cyclic guanosine monophosphate (cGMP) in penile corpus cavernosum smooth muscle cells. Nitric oxide (NO), synthesized from l-arginine, is involved in the increase of cGMP. Therefore, arginine, the substrate, has been attracting attention as a supplement to improve erectile dysfunction (ED). Also, citrulline, which is converted from arginine by NO synthase, is easily reconverted to arginine, and improvement of ED by citrulline intake has been reported (Fig. 114.1). In addition, resveratrol, a type of polyphenol, induces an increase in NO synthase activity by enhancing the activity of one of the sirtuin/sirtuin family, SIRT1, and contributes to the improvement of erectile ability, as reported in animal experiments and clinical studies in humans (Fig. 114.1). The author has reported the improvement of erectile ability by a combination of citrulline and resveratrol in a placebo-controlled double-blind crossover trial [1] (Fig. 114.2). In addition, maca, a species of plant in the Brassicaceae family that grows in Peru, has been reported to be useful for ED in a few studies, although its mechanism is not yet clear, and it is a familiar supplement in Japan.