Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise

Abstract

Dietary nitrate (NO(3)(-)) supplementation with beetroot juice (BR) over 4-6 days has been shown to reduce the O(2) cost of submaximal exercise and to improve exercise tolerance. However, it is not known whether shorter (or longer) periods of supplementation have similar (or greater) effects. We therefore investigated the effects of acute and chronic NO(3)(-) supplementation on resting blood pressure (BP) and the physiological responses to moderate-intensity exercise and ramp incremental cycle exercise in eight healthy subjects. Following baseline tests, the subjects were assigned in a balanced crossover design to receive BR (0.5 l/day; 5.2 mmol of NO(3)(-)/day) and placebo (PL; 0.5 l/day low-calorie juice cordial) treatments. The exercise protocol (two moderate-intensity step tests followed by a ramp test) was repeated 2.5 h following first ingestion (0.5 liter) and after 5 and 15 days of BR and PL. Plasma nitrite concentration (baseline: 454 ± 81 nM) was significantly elevated (+39% at 2.5 h postingestion; +25% at 5 days; +46% at 15 days; P < 0.05) and systolic and diastolic BP (baseline: 127 ± 6 and 72 ± 5 mmHg, respectively) were reduced by ∼4% throughout the BR supplementation period (P < 0.05). Compared with PL, the steady-state Vo(2) during moderate exercise was reduced by ∼4% after 2.5 h and remained similarly reduced after 5 and 15 days of BR (P < 0.05). The ramp test peak power and the work rate at the gas exchange threshold (baseline: 322 ± 67 W and 89 ± 15 W, respectively) were elevated after 15 days of BR (331 ± 68 W and 105 ± 28 W; P < 0.05) but not PL (323 ± 68 W and 84 ± 18 W). These results indicate that dietary NO(3)(-) supplementation acutely reduces BP and the O(2) cost of submaximal exercise and that these effects are maintained for at least 15 days if supplementation is continued.

Effect of dietary nitrate on blood pressure, endothelial function, and insulin sensitivity in type 2 diabetes

“…53 We conclude that the blood pressure lowering effect of a short period of dietary nitrate supplementation seen in healthy young adults does not appear to be applicable to individuals with T2DM. This may reflect diminished vascular reactivity in T2DM, or with ageing, and particularly impaired responsiveness to NO.…”

Dietary nitrate supplementation enhances high-intensity running performance in moderate normobaric hypoxia, independent of aerobic fitness

“…A further strength of this investigation was that the consumption of nitrate-rich foods was not restricted during the study period. This approach, first employed by Vanhatalo and colleagues [51] and later adopted in several subsequent investigations [25,68], preserves ecological validity and demonstrates that nitrate supplementation can alter physiological functioning and exercise performance when participants are consuming their normal diet.…”

“…Blood pressure (BP) of the brachial artery was measured using an automated sphygmomanometer (Omron Healthcare Ltd., Kyoto, Japan) pre-supplementation, pre-hypoxic exposure, pre-exercise, and 5 minutes post-TT. Mean arterial pressure (MAP) was calculated as 1/3·systolic pressure + 2/3·diastolic pressure [51]. At the same time points, a measure of exhaled NO was also recorded, using a hand-held electrochemical analyser (NObreath, Bedfont Scientific Ltd., UK).…”

Improvement in blood pressure after short-term inorganic nitrate supplementation is attenuated in cigarette smokers compared to non-smoking controls

“…However, in spite of a lower salivary [NO 3 -] after NO 3 -ingestion in smokers, the increase in salivary [NO 2 -] was not different between the smokers and non-smokers [44]. It is therefore unclear whether cigarette smoking interferes with the increases in plasma [NO 2 -] and the associated reduction of blood pressure that has been observed following dietary NO 3 -ingestion in non-smokers [12,13,31,33].…”