Acute hemodynamic and autonomic modulation following beetroot and grapefruit juice consumption, alone and in combination, in adults with hypertension: A randomized crossover pilot study

BackgroundDietary strategies such as beetroot juice and grapefruit juice have been proposed to acutely influence blood pressure and autonomic regulation through nitrate and polyphenol-related pathways. However, evidence comparing their individual and combined acute effects in hypertensive adults remains limited.ObjectiveTo investigate the acute effects of beetroot juice, grapefruit juice, and their combined ingestion on blood pressure and heart rate variability (HRV) in adults with hypertension.MethodsIn a randomized crossover pilot study, 15 adults with hypertension consumed beetroot juice, grapefruit juice, and a combined beetroot-grapefruit juice intervention in randomized order, with appropriate washout between visits. Systolic (SBP) and diastolic blood pressure (DBP) and HRV indices were assessed at baseline and at multiple time points up to 4.5 h post-ingestion. Data were analysed using repeated-measures models testing the effects of condition, time, and their interaction. Inferential conclusions were based on between-condition analyses.ResultsSignificant main effects of time were observed for SBP (<i>p</i> = 0.002), DBP (<i>p</i> = 0.006), heart rate (<i>p</i> = 0.004), and selected HRV indices, including the standard deviation of NN intervals (<i>p</i> = 0.034), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (<i>p</i> = 0.028), and the proportion derived by dividing NN50 by the total number of NN intervals (<i>p</i> = 0.049). However, no significant main effects of condition or condition × time interactions were detected for any outcome, indicating that temporal physiological responses did not differ significantly between beetroot juice, grapefruit juice, and their combination.ConclusionAcute time-dependent changes in haemodynamic and autonomic parameters were observed following juice ingestion in hypertensive adults, with no clear differential effects between interventions. These findings are hypothesis-generating and highlight the need for larger, placebo-controlled trials incorporating biochemical validation to clarify potential dietary influences on cardiovascular regulation.