Siervo Mario, Oggioni Clio, Jakovljevic Djordje G, Trenell Michael, Mathers John C, Houghton David, Celis-Morales Carlos, Ashor Ammar W, Ruddock Alan, Ranchordas Mayur, Klonizakis Markos, Williams Elizabeth A
Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne, NE4 5PL, UK.
Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne, NE4 5PL, UK.
Nutr Res. 2016 Dec;36(12):1361-1369. doi: 10.1016/j.nutres.2016.11.004. Epub 2016 Nov 14.
Although dietary nitrate (NO) ingestion appears to enhance exercise capacity and performance in young individuals, inconclusive findings have been reported in older people. Therefore, we conducted a double-blind, crossover randomized clinical trial using beetroot juice in older healthy participants, who were classified as normal weight and overweight. We tested whether consumption of beetroot juice (a rich source of NO) for 1 week would increase nitric oxide bioavailability via the nonenzymatic pathway and enhance (1) exercise capacity during an incremental exercise test, (2) physical capability, and (3) free-living physical activity. Twenty nonsmoking, healthy participants between 60 and 75 years of age and with a body mass index of 20.0 to 29.9 kg/m were included. Presupplementation and postsupplementation resting, submaximal, maximal, and recovery gas exchanges were measured. Physical capability was measured by hand-grip strength, time-up-and-go, repeated chair rising test, and 10-m walking speed. Free-living physical activity was assessed by triaxal accelerometry. Changes in urinary and plasmaNOconcentrations were measured by gas chromatography-mass spectrometry. Nineteen participants (male-to-female ratio, 9:10) completed the study.Beetroot juice increased significantly both plasma and urinary NOconcentrations (P<.001) when compared with placebo. Beetroot juice did not influence resting or submaximal and maximal oxygen consumption during the incremental exercise test. In addition, measures of physical capability and physical activity levels measured in free-living conditions were not modified by beetroot juice ingestion. The positive effects of beetroot juice ingestion on exercise performance seen in young individuals were not replicated in healthy, older adults. Whether aging represents a modifier of the effects of dietary NOon muscular performance is not known, and mechanistic studies and larger trials are needed to test this hypothesis.
尽管摄入膳食硝酸盐（NO）似乎能增强年轻人的运动能力和表现，但关于老年人的研究结果尚无定论。因此，我们在年龄较大的健康参与者中进行了一项双盲、交叉随机临床试验，这些参与者被分为正常体重和超重两类，并使用了甜菜根汁。我们测试了连续1周饮用甜菜根汁（富含NO）是否会通过非酶途径提高一氧化氮的生物利用度，并增强：（1）递增运动试验中的运动能力；（2）身体机能；（3）日常体力活动。纳入了20名年龄在60至75岁之间、体重指数为20.0至29.9kg/m²的不吸烟健康参与者。测量了补充前和补充后静息、次最大、最大和恢复时的气体交换情况。通过握力、起立行走测试、重复椅子起立测试和10米步行速度来测量身体机能。通过三轴加速度计评估日常体力活动。通过气相色谱 - 质谱法测量尿液和血浆中NO浓度的变化。19名参与者（男女比例为9:10）完成了研究。与安慰剂相比，甜菜根汁显著提高了血浆和尿液中的NO浓度（P<0.001）。在递增运动试验中，甜菜根汁对静息、次最大和最大耗氧量没有影响。此外，在自由生活条件下测量的身体机能和体力活动水平指标并未因摄入甜菜根汁而改变。年轻人中观察到的摄入甜菜根汁对运动表现的积极影响在健康的老年人中并未重现。衰老是否是膳食NO对肌肉性能影响的调节因素尚不清楚，需要进行机制研究和更大规模的试验来验证这一假设。
