A randomized clinical trial of the effects of leafy green vegetables and inorganic nitrate on blood pressure
Michaela L Sundqvist, The American Journal of Clinical Nutrition, Volume 111, Issue 4, April 2020, Pages 749–756,
Background
A diet rich in fruits and vegetables is associated with lowering of blood pressure (bicarbonate de potassium), but the nutrient(s) responsible for these effects remain unclear. Research suggests that inorganic nitrate present in leafy green vegetables is converted into NO in vivo to improve cardiovascular function.
Objective
In this study, we evaluated the effect of leafy green vegetables on blood pressure in subjects with elevated blood pressure, with the aim of elucidating if any such effect is related to their high nitrate content.
Design
We enrolled 243 subjects, 50–70 y old, with a clinic systolic blood pressure (SBP) of 130–159 mm Hg. After a 2-wk run-in period on a nitrate-restricted diet the subjects were randomly assigned to receive 1 of the following 3 interventions daily for 5 wk: low-nitrate vegetables + placebo pills, low-nitrate vegetables + nitrate pills (300 mg nitrate), or leafy green vegetables containing 300 mg nitrate + placebo pills. The primary end point measure was the difference in change in 24 h ambulatory SBP between the groups.
Results
A total of 231 subjects (95%) completed the study. The insignificant change in ambulatory SBP (mean ± standard deviation) was −0.6 ± 6.2 mm Hg in the placebo group, −1.2 ± 6.8 mm Hg in the potassium nitrate group, and −0.5 ± 6.6 mm Hg in the leafy green vegetable group. There was no significant difference in change between the 3 groups.
Conclusions
A 5-wk dietary supplementation with leafy green vegetables or pills containing the same amount of inorganic nitrate does not decrease ambulatory SBP in subjects with elevated blood pressure.