Effect of carotenoid supplementation on blood pressure in adults: a GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trials

Context: Hypertension (HTN) is regarded as a serious public health issue throughout the world. High blood pressure (BP) may be improved by carotenoid supplementation; however, randomized controlled trials (RCTs) provide conflicting evidence. Objective: The aim of this study was to evaluate the effects of carotenoid supplementation on BP in RCTs by systematically review and meta-analysis. Data Sources: A comprehensive literature search was performed in the Scopus, PubMed, and Web of Science databases until October 2023, with no limitation on the date or language of publication. Data Extraction: Studies that evaluated the net effects of carotenoids in the form of supplements on BP in adults were selected. Weighted mean differences (WMDs) and 95% confidence intervals (Cls) were calculated on the basis of a fixed or random-effects model. Sensitivity analysis, meta-regression, publication bias, and heterogeneity were assessed using standard methods. Cochrane quality assessments were used to evaluate the included studies' bias risks. Evidence certainty was calculated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework). Data Analysis: Reports on a total of 19 RCTs involving 1151 participants were included in this review. Carotenoid supplementation significantly reduced the systolic BP (SBP) (WMD,-2.492 mmHg; 95%Cl,-4.52,-0.47; P = 0.016) and diastolic BP (DBP) (WMD,-1.60 mmHg; 95%Cl,-2.73,-0.47; P = 0.005). Greater effects were observed in Asian participants, those aged >50 years, nonhealthy participants, and participants with a baseline SBP >130 mmHg and DBP >80 mmHg, at dose >10 mg. Dose-response analysis showed that carotenoid supplementation decreased SBP and DBP levels at doses of, respectively, 0-25 and 0-20 mg/d. Evidence for all SBP, DBP, and heart rate values was high quality. Conclusions: Carotenoid supplementation had a beneficial effect on BP parameters, especially in nonhealthy study participants with high BP baseline levels. PROSPERO registration no: CRD42023402740.