The effect of natural products use on blood pressure in Iran: Systematic review and meta-analysis

Context: Hypertension (HTN) is the leading risk factor for mortality worldwide. People tend to seek traditional therapies since chemical medicines have various side effects and high costs. Aims: Therefore, the present study investigated the effect of natural products on blood pressure in Iran by meta-analysis. Materials and Methods: In this meta-analysis, those initial studies were included that were randomized clinical trials with or without blinded and studies with quasi-experimental design. The national and international databases included Barekat Gostar, SID, Magiran, IranDoc, PubMed, Scopus, Web of Science, Cochrane, and Google Scholar by keywords: natural products, medicinal plants, herbal medicines, pharmaceutical plant, blood pressure, hypertension, Iran. Statistical Analysis Used: The gathered data were analyzed in STATA ver. 14. Results: In 76 studies with a sample size of 2886 subjects, 60 types of natural products were used to reduce blood pressure. The most to the least effective natural products for systolic blood pressure (SBP) were the mixture of garlic and lemon juice, barberry, sour tea, barberry juice, cumin powder, resveratrol, garlic, olive leaf, orange juice, artichoke, flaxseed, saffron, Berberis vulgaris + apple vinegar, and lemon, respectively. Considering the natural products reducing diastolic blood pressure (DBP), the most to the least effective natural products were the mixture of garlic and lemon juice, sour tea, olive leaf, saffron, and olive oil, respectively. Conclusion: Based on the results, the mixture of garlic and lemon juice had the greatest effect on reducing both SBP and DBP levels. It was also found out that its effect was slightly greater in decreasing the SBP than the DBP.