The effects of dietary nitrate supplementation on endurance exercise performance and cardiorespiratory measures in healthy adults: a systematic review and meta-analysis

Systematic review and meta-analysis of randomized controlled trials; healthy adults ≥18 years engaged in endurance-based activities (distance running, cycling, rowing, swimming, kayaking, triathlon).

Dietary nitrate supplementation (oral) via nitrate-rich foods or supplement products; dosing regimens varied across trials; no standardized regimen specified.

Nitrate supplementation increased power output by 4.59 W, time to exhaustion by 25.27 s, and distance traveled by 163.73 m; reduced VO2 by 0.04 L/min; did not significantly affect VO2max (MD 0.04 L/min, 95% CI −0.02 to 0.10), rating of perceived exertion (−0.11 Borg), time trial performance (−1.98 s), work done (0.02 kJ), or blood lactate (−0.08 mM). This suggests dietary nitrate can improve endurance performance by lowering the oxygen cost of exercise, though effects vary and the overall quality of evidence is low to very low; results should be interpreted with caution.

Insufficient reporting of randomization/allocation concealment in many trials; heterogeneity in tests, nitrate sources, doses, and cointerventions; small, selective study populations; external validity limited; products varied in composition.