Beetroot juice: effects on blood pressure, intraocular pressure, and ocular vessel density in healthy adults

Background: The blood pressure (BP)-lowering effect of beetroot is attributed to its high nitrate concentration, which converts to the vasodilator nitric oxide. Nitric oxide may also mediate ocular aqueous outflow to regulate intraocular pressure (IOP). Aims: We investigated the effect of beetroot juice on IOP and ocular vessel density. Subjects and Methods: With a single-blind, crossover design, 19 healthy young adults participated on 2 days 1 week apart. On Visit 1, baseline IOP, BP, and ocular vessel density (optical coherence tomography angiography, disc, and macula) were measured. Three hours after consumption of 16 ounces of beetroot juice or water (randomly assigned), all measurements were repeated.  On Visit 2, baseline and 3-hour post-consumption measurements were assessed, with each subject consuming the drink not ingested on Visit 1. Results: Paired-samples t-test showed 1) no difference in IOP change post-water vs post-beet root juice (P = 0.27), and 2) mean systolic and diastolic BPs were lower only post-beet root juice (systolic:  -4.8 (SEM ± 2.1) mm Hg, P = 0.032, 95% CI (0.47, 9.11); diastolic: -6.2 (SEM± 1.4) mm Hg, P <0.001, 95% CI (3.27, 9.15)). Superficial vessel density was significantly lower in several macular regions post-beet root juice, but not post-water (Wilcoxon signed ranks test, immediately superior, inferior, and temporal to center; respective P values of 0.016, 0.035, and 0.046). Conclusions: Beetroot juice lowers BP and macular vessel density, but does not lower IOP in young, healthy adults. Further investigation into its effect on IOP and vessel density in glaucomatous eyes is warranted.