Effectiveness of herbs taken concurrently with antihypertensive drugs in managing hypertension and lipid outcomes. A systematic review and meta-analysis.

Purpose

Hypertension is the primary cause of mortality. Hence globally, there is a growing interest in complementing antihypertensive drugs with herbs to alleviate blood pressure among hypertensive patients. Thus, this review aimed to evaluate the effectiveness of complementing drugs with herbs on blood pressure and lipid profile outcomes, the associated factors and the types of complementary herbs alongside their consumption regimes.

Methods

This review is registered in PROSPERO on the National Institute of Health Database with an ID: CRD42021270481. Using the PICOS (population, intervention, comparison, outcome, study type) mnemonic formula and search strategy, we searched (January 2010 to February 2024) five electronic databases including Pubmed, Scopus, Web of Science, CINAHL (Cumulative Index for Nursing and Allied Health Literature) and Psychology & Behavioral Sciences Collection (PBSC). The inclusion criteria of the review were that all included papers had to be randomised control trials in English among hypertensive adults who complemented antihypertensive drugs with herbs. A Cochrane risk of bias assessment as well as a meta-analysis and narrative synthesis were conducted to answer the objectives.

Results

Twenty-five randomised controlled trials involving 1996 participants from 14 countries were included. The risk of bias among included articles was assessed and presented using the Cochrane risk of bias tool and the graphs were generated. The effects of complementing antihypertensive drugs with different herb regimes on blood pressure and lipid profile outcomes were compared to those solely on antihypertensive drugs and placebo via a random model effects meta-analysis using the Revman manager. Systolic blood pressure (SBP) and triglycerides gave a significant reduction in favour of the intervention group which complemented herbs. The overall pooled systolic blood pressure showed a reduction of (SMD=0.81, 95 % CI 0.14–1.47, p < 0.02, p for heterogeneity=0.00001, I² =97 %) while triglycerides were (SMD=0.73, 95 % CI 0.17–1.28, p < 0.01, p for heterogeneity=0.00001, I² =85 %). However, diastolic blood pressure, total cholesterol, HDL and LDL did not exert significant outcomes.

Conclusion

The complemented herbs with antihypertensive drugs did show improvement in overall blood pressure management in the majority of the studies compared to the placebo group. Blood pressure and lipid profiles are the health outcomes that enable access to complementing herbs in controlling high blood pressure. Some limitations of this review are attributed to performance, detection and attrition bias in a few included articles alongside the presence of a high heterogeneity overall.