A systematic review and meta-analysis of the effects of Hibiscus sabdariffa on blood pressure and cardiometabolic markers

CONTEXT: Hibiscus sabdariffa (hibiscus) has been proposed to affect cardiovascular risk factors. OBJECTIVE: To review the evidence for the effectiveness of hibiscus in modulating cardiovascular disease risk markers, compared with pharmacologic, nutritional, or placebo treatments. DATA SOURCES: A systematic search of the Web of Science, Cochrane, Ovid (MEDLINE, Embase, AMED), and Scopus databases identified reports published up to June 2021 on randomized controlled trials using hibiscus as an intervention for lipid profiles, blood pressure (BP), and fasting plasma glucose levels in adult populations. DATA EXTRACTION: Seventeen chronic trials were included. Quantitative data were examined using a random effects meta-analysis and meta-regression with trial sequential analysis to account for type I and type II errors. DATA ANALYSIS: Hibiscus exerted stronger effects on systolic BP (−7.10 mmHg [95%CI, −13.00, −1.20]; I(2) = 95%; P = 0.02) than placebo, with the magnitude of reduction greatest in those with elevated BP at baseline. Hibiscus induced reductions to BP similar to that resulting from medication (systolic BP reduction, 2.13 mmHg [95%CI, −2.81, 7.06], I(2) = 91%, P = 0.40; diastolic BP reduction, 1.10 mmHg [95%CI, −1.55, 3.74], I(2) = 91%, P = 0.42). Hibiscus also significantly lowered levels of low-density lipoprotein compared with other teas and placebo (−6.76 mg/dL [95%CI, −13.45, −0.07]; I(2) = 64%; P = 0.05). CONCLUSIONS: Regular consumption of hibiscus could confer reduced cardiovascular disease risk. More studies are warranted to establish an effective dose response and treatment duration. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42020167295