Nitrate-rich beet juice intake on cardiovascular performance in response to exercise in postmenopausal women with arterial hypertension: study protocol for a randomized controlled trial

Abstract

Background There is no evidence of the use of beetroot juice with a previously recommended dose of nitrate (NO3) (> 300 mg) on the cardiovascular performance during and recovery following exercise in postmenopausal women with systemic arterial hypertension (SAH). Methods We will investigate the effects of beetroot juice rich in NO3 acutely (800 mg) and during a week with daily doses (400 mg) on blood pressure, heart rate (HR), cardiac autonomic control, endothelial function, inflammatory, hormonal, and stress biomarkers oxidative stress and enzymes involved in nitric oxide synthesis and mitochondrial regulation, under resting conditions, as well as mediated by submaximal aerobic exercise sessions. Through a randomized, crossover, triple-blind, placebo-controlled clinical trial, 25 physically inactive women with SAH will undergo an acute and 1-week trial, each with two intervention protocols: (1) placebo and (2) beetroot, in which will ingest beet juice with or without NO3 in its composition with a 7-day washout interval. On collection days, exercise will be performed on a treadmill for 40 min at a speed corresponding to 65–70% of VO2peak. The collection of variables (cardiovascular, autonomic, and blood samples for molecular analyses) of the study will take place at rest (135 min after ingestion of the intervention), during exercise (40 min), and in the effort recovery stage (during 60 min) based on previously validated protocols. The collections were arranged so that the measurement of one variable does not interfere with the other and that they have adequate intervals between them. Discussion The results of this research may help in the real understanding of the nutritional compounds capable of generating safety to the cardiovascular system during physical exercise, especially for women who are aging and who have cardiovascular limitations (e.g., arterial hypertension) to perform physical exercise. Therefore, our results will be able to help specific nutritional recommendations to optimize cardiovascular health. Trial registration ClinicalTrials.gov NCT05384340. Registered on May 20, 2022.

Dietary antioxidants and hypertension among menopausal women in Rafsanjan Cohort Study

“…Compared to men, women of reproductive age show a lower risk of hypertension; however, postmenopausal women present a higher risk of hypertension compared to age-matched male counterparts 6 , 7 . This elevated risk has been attributed to multiple factors ranging from estrogen and 17-β-estradiol deficiencies to vascular dysfunction 8 , 9 .…”

The Cardioprotective Role of Nitrate-Rich Vegetables

“…Fresh beetroot fresh juice is most commonly used for nitrate supplementation, but it has a lower concentration compared to other beetroot products ( Table 2 ). Nevertheless, various studies have demonstrated a significant increase in nitrite levels (a marker of NO) in plasma after intake of beetroot juice [ 23 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ].…”

“…Moreover, different papers describe the fact that nitrate supplementation (including green leafy and root vegetables) may have an effect on cardiovascular health. They may help regulate blood pressure, limit a the progression of atherosclerosis, and improve myocardial contractility in healthy subjects and patients with cardiovascular diseases [ 8 , 10 , 23 , 36 , 37 , 39 ]. Figure 1 presents the beneficial action of nitric oxide (its regulatory and protective functions) in the cardiovascular system, together with the nitrate/nitrite/nitric oxide pathways.…”

“…Fresh beetroot fresh juice is most commonly used for nitrate supplementation, but it has a lower concentration compared to other beetroot products (Table 2). Nevertheless, various studies have demonstrated a significant increase in nitrite levels (a marker of NO) in plasma after intake of beetroot juice [23,[28][29][30][31][32][33][34][35][36][37][38][39]. The stability of NO3 − in vegetables and their food products is important when considering their functional activity.…”

“…The cardioprotective action associated with the consumption of fruits and vegetables have been attributed to their constituents, including minerals, fiber, vitamins and secondary metabolites. These cardioprotective properties may be also associated with the consumption of nitrate-rich food products [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Although vegetables represent the primary source of dietary nitrate (about 70–80% of intake), the European Food Safety Authority [ 25 ] report that fruits are also important sources, contributing 50% to 75% to the overall dietary intake.…”