Effects of Nitrate in Vegetables on Blood Pressure in Subjects With Prehypertension

Diet and Nitric Oxide (DINO): A Study on the Effects of Dietary Nitrate on Blood Pressure in Subjects With Prehypertension

The purpose of this study is to examine the effect of different vegetables on cardiovascular function in subjects with moderately increased blood pressure. Specifically we are comparing the effects of vegetables with a high natural content of inorganic nitrate with those of vegetables with a low nitrate content.

Recent studies indicate that dietary-derived inorganic nitrate can affect blood pressure in humans by converting into nitric oxide bioactivity. Here we will study if vegetables that naturally contain high amounts of nitrate (green leafy vegetables) can lower blood pressure and whether any effect is attributed to the nitrate anion. High nitrate vegetables are compared with vegetables low in nitrate (e.g. tomatoes, sweet pepper). After a 2 week run in period where all subjects receive vegetables low in nitrate, the participants are randomized to one of three interventions. One third of the patients receive high-nitrate vegetables + a placebo pill (KCl), one third receives low-nitrate vegetables + placebo and the third group receives low-nitrate vegetables + a nitrate pill (KNO3). The nitrate content in the pill is precisely matched to the nitrate content in the high-nitrate vegetable group.

Inclusion Criteria:

Age 50-70 years Systolic blood pressure >130 at screening visit 2

Exclusion Criteria:

Systolic blood pressure <120 or >159 mm Hg at screening 2 Systolic blood pressure > 169 mm Hg at screening 1 Chronic kidney disease Chronic rheumatic disease Insulin treated diabetes mellitus Atrial fibrillation Major cardiovascular event within 6 months Inflammatory bowel disease Malignancy, actively treated within 6 months Hepatitis Polycytemia Vera