Effects of Beetroot-Derived Nitrate Supplementation in Highly Trained and Elite Athletes: A Scoping Review of...

Background: Beetroot-derived nitrate supplementation is a widely studied nutritional strategy to enhance athletic performance. Although ergogenic benefits have been reported in recreational and moderately trained individuals, evidence for highly trained and elite athletes remains inconsistent. Objectives: This scoping review aimed to map and synthesize evidence from randomized controlled trials (RCTs) investigating the effects of beetroot-derived nitrate supplementation on performance, recovery, and physiological outcomes in highly trained and elite athletes. Methods: The review followed the Joanna Briggs Institute methodology and PRISMA-ScR guidelines. Literature searches were conducted in PubMed, Scopus, and Web of Science. Eligible studies included RCTs involving McKay Tier 3-5 athletes and evaluating beetroot-derived nitrate supplementation as a standalone intervention. Results: Thirty-one RCTs met the inclusion criteria, representing athletes from a wide range of sports. Supplementation protocols varied substantially, with nitrate doses ranging from 4 to 19.5 mmol·day^-1 (248-1209 mg·day^-1) and durations from acute administration to 15 days. Positive effects were most frequently reported for cycling time-trial performance, Yo-Yo intermittent recovery performance, anaerobic power, neuromuscular performance, exercise tolerance, and recovery. In contrast, findings for endurance performance, sport-specific skills, oxygen consumption, and perceptual responses were inconsistent despite marked increases in nitrate and nitrite bioavailability. The outcomes seemed to depend on dosage, duration, sport type, and athletes' training status. Conclusions: Beetroot-derived nitrate supplementation may enhance performance in highly trained and elite athletes, particularly during high-intensity and anaerobic activities. However, the effects are inconsistent, underscoring the need for further research to establish optimal supplementation strategies and evaluate long-term efficacy in elite sporting populations.