THE IMPACT OF CITRULLINE SUPPLEMENTATION ON CARDIOVASCULAR AND EXERCISE PHYSIOLOGY: A NARRATIVE REVIEW

Abstract

Background: L-citrulline is an endogenous non-proteinogenic amino acid involved in nitric oxide (NO) metabolism by increasing L-arginine bioavailability. Its use in sports and cardiovascular disease prevention has gained considerable interest, although its efficacy remains debatable. Aim of the study: The aim of the study is to evaluate current evidence on the effects of L-citrulline supplementation on physical performance and cardiovascular function. Materials and methods: A narrative review of the literature was conducted using PubMed/MEDLINE and Google Scholar. 148 publications were analysed, mainly from 2017–2025, including meta-analyses, systematic reviews, randomised controlled trials, and international guidelines. Results: L-citrulline supplementation increases L-arginine and NO metabolite concentrations, supporting vasodilation and endothelial function. Beneficial effects were reported more often with chronic than acute supplementation. Some studies showed improvements in blood pressure, vascular stiffness, and blood flow, although results remain inconsistent. In exercise settings, supplementation was associated with improved selected resistance-training outcomes and reduced perceived fatigue and post-exercise muscle soreness. Evidence regarding effects on strength, power, and aerobic capacity remains inconclusive. Conclusions: L-citrulline is a safe and well-tolerated supplement with potential benefits for endothelial function, selected cardiovascular parameters, and some aspects of exercise performance. However, the heterogeneity of available studies prevents firm conclusions, highlighting the need for further long-term randomised clinical trials.