Absence of an effect of high nitrate intake from beetroot juice on blood pressure in treated hypertensive individuals: a randomized controlled trial

Am J Clin Nutr. 2015 Aug;102(2):368-75. doi: 10.3945/ajcn.114.101188. Epub 2015 Jul 1.

Abstract

Background: Dietary nitrate, which is in green leafy vegetables and beetroot, decreases blood pressure through the enterosalivary nitrate-nitrite-nitric oxide pathway in healthy individuals. Whether similar effects would occur in individuals with treated hypertension and, therefore, at increased risk of cardiovascular disease is unclear.

Objective: We assessed whether increased dietary nitrate intake by using beetroot juice for 1 wk lowers blood pressure in treated hypertensive men and women.

Design: Participants (n = 27) were recruited to a randomized, placebo-controlled, double-blind crossover trial. The effect of 1-wk intake of nitrate-rich beetroot juice was compared with 1-wk intake of nitrate-depleted beetroot juice (placebo). The primary outcome was blood pressure assessed by measuring home blood pressure during the intervention and 24-h ambulatory blood pressure on day 7 of the intervention. Other outcomes included nitrate metabolism assessed by measuring nitrate and nitrite in plasma, saliva, and urine.

Results: Relative to the placebo, 1-wk intake of nitrate-rich beetroot juice resulted in a 3-fold increase in plasma nitrite and nitrate, a 7-fold increase in salivary nitrite, an 8-fold higher salivary nitrate, and a 4-fold increase in both urinary nitrite and nitrate (P < 0.001). However, no differences in home blood pressure and 24-h ambulatory blood pressure were observed with 1-wk intake of nitrate-rich beetroot juice in comparison with the placebo.

Conclusion: An increase in dietary nitrate intake may not be an effective short-term approach to further lower blood pressure in treated hypertensive subjects.

Keywords: beetroot; blood pressure; hypertension; nitrate; nitric oxide.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Antihypertensive Agents / therapeutic use*
  • Beta vulgaris* / chemistry
  • Beverages* / analysis
  • Combined Modality Therapy
  • Cross-Over Studies
  • Double-Blind Method
  • Drug Resistance
  • Drug Resistance, Multiple
  • Drug Therapy, Combination
  • Female
  • Humans
  • Hypertension / diet therapy*
  • Hypertension / drug therapy
  • Male
  • Middle Aged
  • Nitrates / analysis
  • Nitrates / therapeutic use*
  • Nitrates / urine
  • Nitrites / analysis
  • Nitrites / blood
  • Nitrites / urine
  • Plant Roots* / chemistry
  • Saliva / chemistry
  • Western Australia

Substances

  • Antihypertensive Agents
  • Nitrates
  • Nitrites

Associated data

  • ANZCTR/ACTRN12613000116729