Association between dietary phytochemical index adherence and hypertension: a systematic review and meta-analysis of observational studies

Due to inconsistency in the available evidence regarding the association of adherence to dietary phytochemical index (DPI) and hypertension, this study aimed to assess this relationship by conducting a meta-analysis. A comprehensive search was performed in PubMed, Scopus, Web of Science ISI databases, as well as Google Scholar search engine to find eligible studies, including observational studies investigating the association between the score of phytochemical index and odds of hypertension in adults, and reported this association as relative effect measures, up to March 2025. The odds ratio (OR) with 95% confidence interval (95% CI) of included studies, as reported by comparing the highest score of the dietary phytochemical index with the lowest, was used to calculate the overall effect size. Polling ten effect sizes from nine included studies showed that the highest score of the phytochemical index was significantly associated with 14% lower odds of hypertension compared to the lowest score (OR: 0.86; 95% CI: 0.78–0.96, P = 0.006; 81,346 individuals). Also, there was no significant heterogeneity among the combined effect sizes (I2 = 24.5%; P = 0.21). This systematic review and meta-analysis revealed that adherence to the PDI may related to the lower odds of hypertension. However, to assess the impacts of adherence to DPI on blood pressure, randomized controlled trials are needed.