Effects of Nutritional Supplements on Vascular Function: A Narrative Review

Vascular aging is a key determinant of cardiovascular risk and is characterized by endothelial dysfunction, oxidative stress, inflammation, arterial stiffness, and alterations of the endothelial glycocalyx. In recent years, increasing scientific interest has focused on whether selected nutritional supplements can modulate these mechanisms. The objective of this narrative review is to summarize and critically evaluate the current evidence regarding the effects of selected nutritional supplements on endothelial function and vascular health, with emphasis on their proposed mechanisms of action, available preclinical and clinical evidence, and current limitations. This review examines nutritional supplements targeting nitric oxide biology (L-arginine/L-citrulline and citrulline derived from watermelon), polyphenol-rich foods and extracts (cocoa flavan-3-ols and grape polyphenols), mitochondrial redox balance (coenzyme Q10 and the mitochondria-targeted antioxidant MitoQ), endothelial glycocalyx-supporting formulations, olive-derived bioactive compounds, curcumin, and S-allyl cysteine. Across studies, improvements have been reported primarily in surrogate vascular endpoints, including flow-mediated dilation, pulse wave velocity, and blood pressure, although effect sizes vary and substantial heterogeneity exists among studies. Overall, current evidence suggests that several nutritional supplements may improve surrogate markers of vascular function; however, evidence demonstrating reductions in major cardiovascular events or cardiovascular mortality remains limited. Future research should prioritize adequately powered randomized controlled trials with longer follow-up, standardized supplement formulations, and clinically meaningful cardiovascular outcomes to more clearly define the role of nutritional supplements in cardiovascular prevention.