Increased nitrate intake from beetroot juice over 4 weeks affects nitrate metabolism, but not vascular function or blood pressure in older adults with hypertension

Fig. 1. Study design. FBF, forearm blood flow.

Fig. 2. Consort flow diagram for participant recruitment. Consort, consolidated standards of reporting trials.

Fig. 3. Plasma and salivary concentrations of nitrate and nitrite before (PRE), and 3 hours (3h post) after intake of the first dose of nitrate-rich (nitrate; ∼400 mg nitrate) versus nitrate-depleted (placebo) beetroot juice, and 4 weeks (4WK POST) after daily nitrate-rich (nitrate; ∼800 mg nitrate) versus nitrate-depleted (placebo) juice consumption. Group data (bars) are presented as mean ± sd, and individual data are indicated with circles (n = 15; 10 men, 5 women). PRE versus POST: *, p < 0.05; **, p < 0.01; ***, p < 0.001; nitrate versus placebo: #, p < 0.01; ##, p < 0.001. Data were compared using a repeated-measures linear mixed-model.

Fig. 4. POST- versus pre-intervention forearm blood flow (FBF)-area under the curve (AUC) ratios for FBF measurements in response to acetylcholine (ACH) or glyceryltrinitrate (GTN) 3 hours (3H POST) versus baseline (PRE) and 4 weeks (4WK POST) versus PRE after the interventions with nitrate-rich (nitrate) or nitrate-depleted (placebo) beetroot juice. Data are presented as mean and 95% confidence interval (n = 15; 10 men, 5 women). Data were compared using a repeated-measures linear mixed-model and a tukey post hoc-correction.

Fig. 5. Forearm blood flow (FBF) responses calculated as area under the curve (AUC) in the interventional- versus control arm in response to acetylcholine (FBFACh-AUC) and glyceryltrinitrate (FBFGTN-AUC) before (PRE), and 3 hours (3H POST) and 4 weeks (4WK POST) after the interventions with nitrate-rich (nitrate) or nitrate-depleted (placebo) beetroot juice. Group data (bars) are presented as mean ± sd, and individual data are indicated with circles (n = 15; 10 men, 5 women). PRE versus 3H POST: *, p < 0.05. Data were compared using a repeated-measures linear mixed-model.