Beetroot juice of no benefit to blood pressure, endothelial function

Beetroot juice does not seem to be effective at lowering blood pressure or improving microvascular endothelial function in both young and old people, a recent study has found.

Twenty-five participants were enrolled into the double-blind, randomized, placebo-controlled study. A single dose of beetroot juice providing 6.4 mmol of nitrate was the active treatment, while controls were given nitrate-depleted beetroot juice. Outcomes included microvascular function assessed by laser Doppler flowmetry, urinary nitrate levels, and blood pressure. Analyses were stratified according to age group (18–35 and ≥55 years).

In young patients, the nitrate-containing beetroot juice yielded no significant difference in systolic (SBP; mean difference, –0.74) and diastolic (DBP; mean difference, 1.4) blood pressure and heart rate (HR; mean difference, 0.4) as compared with placebo controls. Similarly, cutaneous vascular conductance at initial peak and at plateau did not significantly differ between the nitrate and placebo arms (p≥0.05 for all).

Older adults likewise derived no significant benefit from nitrate-rich beetroot juice in terms of blood pressure indices: SBP (mean difference, 30.4), DBP (mean difference, 16), and HR (mean difference, –1.2). Microvascular function was also not significantly different between the nitrate and placebo arms (p≥0.05 for all).

“We suggest that future work should be undertaken to elucidate the minimum effective dose for nitrate supplementation and that more work is needed to explore dose-by-time interactions. Such findings are perhaps important if further work is to continue in this area,” the researchers said.