Beetroot Supplementation as a Nutritional Strategy to Support Post-Exercise Autonomic Recovery in Postmenopausal Women: A Systematic Review and Meta-Analysis

Background/Objectives: Beetroot supplementation is a rich source of inorganic nitrate and has been proposed to enhance nitric oxide bioavailability and support cardiovascular recovery after exercise. This study aimed to evaluate the effects of beetroot supplementation on post-exercise cardiovascular and autonomic recovery in postmenopausal women. Methods: A systematic review and meta-analysis were conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Searches were performed in PubMed, Scopus, and Web of Science databases from inception to July 2025. Ten trials involving postmenopausal women were included. Outcomes assessed included cardiovascular measures (blood pressure and vascular function), autonomic parameters derived from heart rate variability (HRV)—specifically the root mean square of successive differences (RMSSD), the standard deviation of normal-to-normal intervals (SDNN), and high-frequency power (HF)—as well as physical performance (peak oxygen uptake [VO2peak or VO2max] and functional fitness tests). Four independent reviewers extracted data, assessed risk of bias, and evaluated the certainty of evidence using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Results: Pooled analyses from two trials (n = 54) revealed a statistically significant improvement in RMSSD with beetroot supplementation (mean difference: 6.68 ms; 95% CI: 0.86 to 12.50; p = 0.02), suggesting enhanced parasympathetic reactivation after exercise. No significant effects were detected for HF (mean difference: 61.75 ms2; 95% CI: −70.92 to 194.43; p = 0.36) or SDNN (mean difference: 6.20 ms; 95% CI: −9.69 to 22.09; p = 0.44). Substantial to considerable heterogeneity was identified across outcomes (I2 = 73–86%). Certainty of evidence was rated moderate for RMSSD, low for SDNN, and very low for HF. Conclusions: Beetroot supplementation may enhance post-exercise autonomic recovery in postmenopausal women, primarily through improvements in RMSSD. However, further trials with standardized protocols, larger samples, and longer intervention durations are required to clarify its impact on broader HRV domains, cardiovascular function, and clinical outcomes.