Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis.

Systematic review and meta-analysis of 16 randomized clinical trials including 254 adults with crossover designs. Participants were mostly healthy, young, nonsmoking men, with some older healthy adults and overweight or obese adults with type 2 diabetes; seven studies also enrolled physically active men for exercise-performance outcomes.

Oral beetroot juice or inorganic nitrate supplementation, typically given daily in short-term randomized crossover trials against placebo. Beetroot juice provided 5.1 to 45 mmol/day nitrate (321 to 2790 mg/day) in 140 to 500 mL/day, and inorganic nitrate provided 2.5 to 24 mmol/day (157 to 1488 mg/day) as sodium nitrate or potassium nitrate; some beetroot juice preparations were concentrated solutions.

Overall, inorganic nitrate and beetroot juice supplementation reduced systolic blood pressure, while the effect on diastolic blood pressure was smaller and less consistent. Pooled systolic BP decreased by 4.4 mm Hg (95% CI 5.9 to 2.8; P < 0.001), whereas diastolic BP decreased by 1.1 mm Hg (95% CI 2.2 to 0.1; P = 0.06). Beetroot juice and inorganic nitrate showed similar systolic BP effects, with reductions of 4.5 mm Hg and 4.2 mm Hg, respectively; diastolic effects were not significant for either intervention. Higher daily inorganic nitrate dose appeared to be associated with greater systolic BP lowering. Findings come from short-term, small crossover trials, mostly in healthy young men, so applicability to women and people with cardiovascular or metabolic disease remains uncertain.

Evidence was based on small, short-duration crossover trials, many of which enrolled mostly healthy young men. Generalizability to women, older adults, and higher-risk cardiometabolic populations is limited, and long-term efficacy and safety were not tested. Reporting of sex distribution, adherence, and dietary control was incomplete in some studies.