Dr Vikas Kapil (Barts and the London School of Medicine and Dentistry, London, UK) and colleagues observed significant reductions in systolic and diastolic BP as measured in the clinic, at home, or by ambulatory blood pressure monitoring (ABPM) among patients who who drank 250 mL of the juice daily, for a nitrate dosage of approximately 6.4 mmol/day. The same amount of nitrate-depleted beetroot juice served as the placebo.
Improvements in endothelial function and a reduction in arterial stiffness were also observed in the dietary-nitrate group compared with no change in either parameter in placebo controls.
"This is the first evidence of durable BP reduction with dietary-nitrate supplementation in a relevant patient group," Kapil writes.
"And these findings suggest a role for dietary nitrate as an affordable, readily available adjunctive treatment in the management of patients with hypertension."
The study, a prospective, single-center, double-blind, randomized, placebo-controlled trial involving 64 evaluable patients, was published online November 24, 2014 in Hypertension.
All patients completed the dietary interventions for the duration of the study. Hypertension was confirmed by ABPM at study enrollment in all patients.
Dietary-nitrate consumption was associated with a decrease in BP in the clinic, at 24-hour ABPM, and on home readings in the beetroot-juice group compared with baseline.
No change in BP on any of the three measurements was observed among placebo controls.
Reductions in BP Compared With Baseline at Study End Point
|Group||Mean clinic BP reductions, mm Hg (P)||Mean ABP monitoring reductions, mm Hg (P) (mean)||Mean home BP reductions (mean) (week 6)|
|Dietary nitrate group|
|Systolic BP||7.7 (<0.001)||7.7 (<0.001)||8.1 (P<0.001)|
|Diastolic BP||2.4 (0.050)||5.2 (<0.001)||3.8 (P<0.01)|
|Systolic BP||No change||No change||No change|
|Diastolic BP||No change||No change||No change|
There was no evidence for a declining nitrate effect over time.
Noteworthy as well, investigators observed about a 20% improvement in endothelial function (P<0.001) after 4 weeks in the nitrate group compared with the placebo group, which showed no change in endothelial function.
They also observed a decrease in arterial stiffness by 0.59 m/s (P<0.01) following dietary-nitrate consumption compared with baseline and a similar reduction of 0.58 m/s compared with placebo (P<0.05).
As the authors explain, ingestion of dietary (inorganic) nitrate elevates circulating and tissue levels of nitrite via bioconversion in the enterosalivary circulation.
In addition, nitrite is a potent vasodilator in humans, an effect thought to underlie the study's observed BP-lowering effects of dietary nitrate.
Supplementation of dietary nitrate as used in this study led to about a 5.5-fold increase in plasma nitrate concentrations, as the authors observe, while plasma nitrite concentrations were elevated by approximately 2.7-fold from baseline.
"Irrespective of the method of measurement, the magnitude of BP reduction is of clinical significance because it resembles the average BP reduction achieved with a single antihypertensive medication at standard dose (9.1/5.5 mm Hg)," the authors state.
"[And] these appropriately powered data are the first to demonstrate sustained BP-lowering with dietary nitrate in patients with hypertension that require BP control."
The study was funded by The British Heart Foundation. Kapil had no relevant financial relationships. Disclosures for the coauthors are listed in the article.
Heartwire from Medscape © 2014 Medscape, LLC
Cite this: Beetroot Juice Lowers Blood Pressure in Hypertensives - Medscape - Dec 02, 2014.