Abstract
- Background
Beetroot is widely recognized as a complementary and alternative dietary intervention for the management of hypertension, an effect traditionally attributed to its exceptionally high inorganic nitrate (NO_3^ )content. However, the precise clinical magnitude of these effects and the contribution of alternative bioactive mechanisms require rigorous quantification. This systematic review and meta-analysis aimed to evaluate the impacts of beetroot juice supplementation on resting systolic blood pressure (SBP) and diastolic blood pressure (DBP), while elucidating potential dose-response dynamics and nitrate-independent pathways.
- Methods
A comprehensive systematic literature search was executed across PubMed, Scopus, and Embase databases, alongside reference lists of relevant prior reviews. Randomized clinical trials investigating the effects of beetroot juice on resting human blood pressure published between 2009 and 2017 were recruited for methodological quality assessment, meta-analyses, subgroup analyses, and meta-regressions. A total of 22 eligible studies comprising 47 intervention groups ($n = 650$) and 43 control groups ($n = 598$) were systematically analyzed.
- Results
The meta-analytic synthesis demonstrated that both systolic blood pressure (weighted mean difference: $-3.55$ mm Hg; 95% confidence interval [CI]: $-4.55$, $-2.54$ mm Hg) and diastolic blood pressure (weighted mean difference: $-1.32$ mm Hg; 95% CI: $-1.97$, $-0.68$ mm Hg) were significantly lower in the beetroot juice-supplemented groups compared to control cohorts. Subgroup evaluations revealed that greater reductions in SBP occurred in studies with longer intervention durations ($\ge 14$ days compared with $< 14$ days; $-5.11$ vs. $-2.67$ mm Hg) and higher daily juice volumes ($500$ mL/day compared with $70$ and $140$ mL/day; $-4.78$ vs. $-2.37$ mm Hg). A positive correlation was observed between total daily beetroot juice volume and blood pressure mean differences. Conversely, a smaller effect size on blood pressure reductions was associated with higher baseline nitrate concentration per 100 milliliters of juice. Furthermore, meta-analysis of trials utilizing nitrate-depleted beetroot juice as a placebo demonstrated notable blood pressure reductions ($-3.09$ mm Hg for SBP and $-0.81$ mm Hg for DBP), highlighting the presence of meaningful nitrate-independent therapeutic effects.
- Conclusions
These findings robustly confirm the blood pressure-لowering efficacy of beetroot juice and underscore the significant role of potential nitrate-independent active compounds within its complex phytochemical matrix.
https://advances.nutrition.org/article/S2161-8313(22)00816-X/fulltext