Plasma Nitrate and Nitrite Kinetics after Single Intake of Beetroot Juice in Adult Patients on Chronic Hemodialysis and in Healthy Volunteers: A Randomized, Single-Blind, Placebo-Controlled, Crossover Study

Abstract

Nitric oxide (NO) contributes to maintaining normal cardiovascular and renal function. NO is generally formed enzymatically by NO synthase in the vascular endothelium. NO bioactivity can also be attributed to dietary intake of inorganic nitrate, which is abundant in our diet, especially in green leafy vegetables and beets. Ingested nitrate is reduced to nitrite by oral commensal bacteria and further to NO systemically. Previous studies have shown that dialysis, by means of removing nitrate and nitrite from the body, can reduce NO bioactivity. Hence, dietary intervention approaches aimed to boost the nitrate–nitrite–NO pathway may be of benefit in dialysis patients. The purpose of this study was to examine the kinetics of plasma nitrate and nitrite after a single intake of nitrate-rich concentrated beetroot juice (BJ) in adult hemodialysis (HD) patients and in healthy volunteers (HV). Eight HD patients and seven HV participated in this single center, randomized, single-blind, placebo-controlled, crossover study. Each participant received a sequential single administration of active BJ (70 mL 400 mg nitrate) and placebo BJ (70 mL 0 mg nitrate) in a random order separated by a washout period of seven days. For the kinetic analysis, blood samples were collected at different time-points before and up to 44 h after BJ intake. Compared with placebo, active BJ significantly increased plasma nitrate and nitrite levels both in HD patients and HV. The area under the curve and the maximal concentration of plasma nitrate, but not of nitrite, were significantly higher in HD patients as compared with HV. In both groups, active BJ ingestion did not affect blood pressure or plasma potassium levels. Both BJs were well tolerated in all participants with no adverse events reported. Our data provide useful information in planning dietary nitrate supplementation efficacy studies in patients with reduced NO bioactivity.

Renal replacement therapy removes a large number of nitric oxide donors responsible for the nitrate–nitrite–nitric oxide pathway

“…The clinical benefits of dietary supplementation in individuals with reduced NO bioactivity, such as those with chronic kidney disease, including HD patients, are substantial. 15…”

“…The clinical benefits of dietary supplementation in individuals with reduced NO bioactivity, such as those with chronic kidney disease, including HD patients, are substantial. 15 Patients undergoing dialysis thrice per week or continuous RRT may experience rapid changes in NO or lower blood concentrations. After RRT, NO concentration was speculated to be low in the blood stream because of our results showing high NO clearance.…”

Nephroprotective and Anti-Diabetic Potential of Beta vulgaris L. Root (Beetroot) Methanolic Extract in a Rat Model of Type 2 Diabetes Mellitus

“…NO may be produced via the canonical NO synthase-catalyzed oxidation of L-arginine and also by the sequential reduction of nitrate to nitrite and then to NO [ 1 ]. The body’s nitrate stores can be augmented by the ingestion of nitrate-rich foods [ 2 ]. Due to its abundant nitrate content, beetroot ( Beta vulgaris ) intake is well recognized to impart beneficial health effects such as lowering blood pressure, cognitive impairment, and risk of developing cardiovascular and other metabolic diseases [ 3 , 4 ].…”