The effect of nitrate supplementation on blood pressure:A meta-analysis

Objective The meta-analysis was used to systematically evaluate the effects of nitrate supplementation on blood pressure, so as to provide a theoretical reference for prevention and treatment of hypertension. Methods Studies regarding antihypertensive effect of nitrate were collected via retrieving PubMed, Web of Science, Scopus and Science Direct. The Stata software was used to statistically analyze all outcomes included in the eligible literature, and the Egger’s test was used to evaluate the publication bias. Results A total of 24 studies with 379 participants were included in the final analysis. The results indicated that, compared with the placebo, nitrate intake can significantly decrease the systolic blood pressure（SBP:-2.48 mm Hg, 95%CI-4.47 to-0.49 mm Hg, P＜0.05） and the diastolic blood pressure（DBP:-1.85 mm Hg, 95%CI-3.38 to-0.32 mm Hg, P＜0.05）. Meta-regression analysis showed that antihypertensive effect of nitrate was associated with its dose. The further subgroup analysis indicated that high-dose supplementation（≥500 mg/d） can decrease resting SBP（-4.24 mm Hg, 95%CI-5.88 to-2.60 mm Hg, P＜0.01） and DBP（-2.46 mm Hg, 95%CI-4.81 to-0.10 mm Hg, P=0.04） without heterogeneity（both I~2=0%）. Conclusions As a nutritional supplement, nitrate can decrease resting SBP and DBP. Besides, the effect can be enhanced via increment of supplementation dose.