Kang Chao, Lin Ning, Xiong Yanle, Yang Yi, Shi Jiaojiao, Zeng Kaihong, Ma Xin
Department of Clinical Nutrition, The General Hospital of Western Theater Command, Chengdu, Sichuan, China.
Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
PLoS One. 2025 Apr 9;20(4):e0319667. doi: 10.1371/journal.pone.0319667. eCollection 2025.
Nitrate is a dietary intervention commonly used to enhance exercise capacity, including cardiopulmonary fitness, yet its effectiveness has been recently questioned at high altitudes. This meta-analysis systematically evaluates the effects of dietary nitrate supplements on cardiopulmonary fitness at high altitude, as reflected in the biomarker of cardiopulmonary fitness, paving the way for informed dietary strategies.
We conducted a systematic assessment and meta-analysis of randomized controlled trials to examine the effects of dietary nitrate supplementation on biomarkers of cardiorespiratory health at high altitude. Studies were included if they involved healthy individuals (≥16 years of age) engaging in endurance activities such as hiking, long-distance running, mountain climbing, or bicycling at high altitude. Outcomes of interest included nitrite levels (NO2-), maximal oxygen uptake (VO2max), heart rate (HR), perceived exertion (RPE), and pulse oxygen saturation (SpO2). Exclusion criteria included duplicate publications, non-human studies, studies with missing data that could not be retrieved, non-randomized clinical trials, and non-original research articles such as conference papers, expert consensus, or reviews. Our search for articles was conducted across PubMed, Scopus, Web of Science, and Embase, without any language restrictions. A random effects model was employed for quantitative data analysis, utilizing Standardized Mean Difference (SMD) and 95% confidence intervals as summary statistics. The methods and results were reported according to the PRISMA2020 statement.
A total of 9 studies with a sample size of 161 cases were included in the analysis. The meta-analysis indicated that dietary nitrate supplement significantly elevated NO2- concentration (95% CI: 1.38 to 3.12; SMD = 2.25, P < 0.00001; I2 = 70%). However, there was no significant effect observed on VO2max (95% CI: -0.58 to 0.23; SMD = -0.17, P = 0.76; I2 = 0%), HR (95% CI: -0.31 to 0.23; SMD = -0.04, P = 0.77; I2 = 0%), RPE scores (95% CI: -0.49 to 0.18; SMD = -0.16, P = 0.36; I2 = 0%), and SpO2 percentage (95% CI: -0.36 to 0.20; SMD = -0.08, P = 0.58; I2 = 0%).
The current meta-analysis indicates that dietary nitrate intake is less correlated with cardiopulmonary fitness at high altitudes, and further research is required to clarify its impact on exercise capacity.
硝酸盐是一种常用的饮食干预手段，用于提高运动能力，包括心肺适能，但最近其在高海拔地区的有效性受到质疑。本荟萃分析系统评估了膳食硝酸盐补充剂对高海拔地区心肺适能的影响，以心肺适能生物标志物为依据，为合理的饮食策略提供依据。
我们对随机对照试验进行了系统评估和荟萃分析，以研究膳食硝酸盐补充剂对高海拔地区心肺健康生物标志物的影响。纳入的研究需涉及健康个体（≥16岁），在高海拔地区进行耐力活动，如徒步、长跑、登山或骑自行车。感兴趣的结局指标包括亚硝酸盐水平（NO2-）、最大摄氧量（VO2max）、心率（HR）、主观用力程度（RPE）和脉搏血氧饱和度（SpO2）。排除标准包括重复发表的文献、非人体研究、无法获取缺失数据的研究、非随机临床试验以及非原创研究文章，如会议论文、专家共识或综述。我们在PubMed、Scopus、Web of Science和Embase上进行文献检索，无语言限制。采用随机效应模型进行定量数据分析，以标准化均数差（SMD）和95%置信区间作为汇总统计量。根据PRISMA2020声明报告方法和结果。
分析共纳入9项研究，样本量为161例。荟萃分析表明，膳食硝酸盐补充剂显著提高了NO2-浓度（95%CI：1.38至3.12；SMD = 2.25，P < 0.00001；I2 = 70%）。然而，未观察到对VO2max（95%CI：-0.58至0.23；SMD = -0.17，P = 0.76；I2 = 0%）、HR（95%CI：-0.31至0.23；SMD = -0.04，P = 0.77；I2 = 0%）、RPE评分（95%CI：-0.49至0.18；SMD = -0.16，P = 0.36；I2 = 0%）和SpO2百分比（95%CI：-0.36至0.20；SMD = -0.08，P = 0.58；I2 = 0%）有显著影响。
当前的荟萃分析表明，高海拔地区膳食硝酸盐摄入量与心肺适能的相关性较低，需要进一步研究以阐明其对运动能力的影响。
