Acute Effects of Dietary Nitrate on Exercise Tolerance, Muscle Oxygenation, and Cardiovascular Function in Patients With Peripheral Arterial Disease

Abstract

Previous studies have used supplements to increase dietary nitrate intake in clinical populations. Little is known about whether effects can also be induced through vegetable consumption. Therefore, the aim of this study was to assess the impact of dietary nitrate, through nitrate-rich vegetables (NRV) and beetroot juice (BRJ) supplementation, on plasma nitrate and nitrite concentrations, exercise tolerance, muscle oxygenation, and cardiovascular function in patients with peripheral arterial disease. In a randomized crossover design, 18 patients with peripheral arterial disease (age: 73 ± 8 years) followed a nitrate intake protocol (∼6.5 mmol) through the consumption of NRV, BRJ, and nitrate-depleted BRJ (placebo). Blood samples were taken, blood pressure and arterial stiffness were measured in fasted state and 150 min after intervention. Each intervention was followed by a maximal walking exercise test to determine claudication onset time and peak walking time. Gastrocnemius oxygenation was measured by near-infrared spectroscopy. Blood samples were taken and blood pressure was measured 10 min after exercise. Mean plasma nitrate and nitrite concentrations increased (nitrate; Time × Intervention interaction; p < .001), with the highest concentrations after BRJ (494 ± 110 μmol/L) compared with NRV (202 ± 89 μmol/L) and placebo (80 ± 19 μmol/L; p < .001). Mean claudication onset time and peak walking time did not differ between NRV (413 ± 187 s and 745 ± 220 s, respectively), BRJ (392 ± 154 s and 746 ± 176 s), and placebo (403 ± 176 s and 696 ± 222 s) (p = .762 and p = .165, respectively). Gastrocnemius oxygenation, blood pressure, and arterial stiffness were not affected by the intervention. NRV and BRJ intake markedly increase plasma nitrate and nitrite, but this does not translate to improved exercise tolerance, muscle oxygenation, and/or cardiovascular function.

Effects of short-term dietary nitrate supplementation on exercise and coronary blood flow responses in patients with peripheral artery disease

“…The lack of improvement in pain-free (claudication onset) or peak treadmill walk time in the present study was unexpected given previous individual reports showing improved walk test performance after acute ( 26 , 27 , 42 ) or chronic ( 25 ) inorganic nitrate supplementation in PAD patients. However, two additional supplementation studies, one using BR nitrate acutely ( 28 ) (70 mL Beet-IT) and one that administered sodium nitrite tablets for 3 months ( 43 ) reported no significant improvements in walk distances relative to placebo. When examined collectively in a recent meta-analysis of studies investigating dietary nitrate and other upregulators of NO in PAD ( 44 ), it was reported that the improvements in maximum walk distance/duration did not achieve statistical significance.…”

Effect of Dietary Supplements Which Upregulate Nitric Oxide on Walking and Quality of Life in Patients with Peripheral Artery Disease: A Meta-Analysis

“…The dietary interventions tested were diverse and spanned the four different categories as described in Figure 1-NO donors in seven trials [31,45,47,55,58,62,65], antioxidants in nineteen trials [32][33][34][36][37][38][39][40][42][43][44]46,48,49,51,57,59,60,63], NOS inducers in four trials [50,53,61,66] and enhancers of NO availability in five trials (Table S1) [41,52,54,56,64]. Twenty-six RCTs had control groups that received a matched placebo that was identical in all aspects and nine used a non-identical placebo but otherwise similar management to the intervention group.…”

“…Figure 4. Forest plot showing the effect of dietary supplements upregulating the NO pathway versus control on the maximum walking distance; studies stratified by risk of bias[33,34,36,37,39,43,45,47,[50][51][52][53][54][56][57][58]62,64].…”

A Brief Overview of the Effects of Exercise and Red Beets on the Immune System in Patients with Prostate Cancer

“…Most of the studies have been related to the health effects of beet consumption on people with cardiovascular disease who have reduced aerobic capacity, intolerance to exercise, and early onset of fatigue during physical activity and daily activities [86]. Avoort et al studied the effect of beet consumption before exercise in patients with arterial disease [87]. They showed that beets significantly delayed the onset of fatigue while walking on a treadmill.…”

“…They showed that beets significantly delayed the onset of fatigue while walking on a treadmill. The mechanism of this process through the dilation of blood vessels and delivery of oxygen to active tissues have been mentioned [87]. Reddy et al [88] investigated the effect of beets on cancer cell growth and observed the inhibition of MCF-7 cell growth after the consumption of beets for 48 h. The anti-cancer properties of red beets have been investigated [66].…”