The dose–response effects of nitrate-rich beetroot ingestion on cardiovascular and endothelial function: a randomised controlled trial

Abstract

Dietary nitrate (NO₃⁻) supplementation has been reported to improve cardiovascular health, but beyond its effects on brachial artery blood pressure (BP), dose–response effects on other cardiovascular variables are unclear. This study assessed the effects of three acute NO₃⁻ doses (200 mg, 400 mg, 800 mg NO₃^--rich beetroot powder) on brachial and aortic BP, arterial stiffness and macrovascular endothelial function, in a double-blind, randomised, crossover design. Cardiovascular variables and venous blood samples were measured prior to (control) and 2.5 h post supplement ingestion. Dietary NO₃⁻ supplementation increased plasma [NO₃⁻] and plasma [nitrite] but had no effect on cyclic guanosine monophosphate (cGMP) concentration. Arterial stiffness markers improved following all NO₃⁻ doses, with no between-dose differences. However, endothelial function only improved following 400 mg (+3.07% compared to control) and aortic systolic BP only improved following 800 mg (−4 mmHg compared to control) dietary NO₃⁻ supplementation. Acute NO₃⁻ ingestion improved some cardiovascular risk factors, including arterial stiffness, macrovascular endothelial function and aortic systolic BP with different dose–response effects, but had no effect on brachial BP or plasma [cGMP]. These findings improve our understanding of NO₃⁻ supplementation and cardiovascular function in healthy adults.