The Effect of Spirulina Supplementation on Blood Pressure in Adults: A GRADE-Assessed Systematic Review and Meta-Analysis of Randomized Clinical Trials

Previous studies have yielded controversial results regarding the effect of spirulina on blood pressure (BP), which need updating. So, this updated systematic review and meta-analysis of randomized controlled trials (RCTs) carry out a more accurate estimation of the effect of spirulina on BP in adults. This systematic searches (in PubMed/Medline, Scopus, and ISI Web of Science) until April 1, 2024, to identify related RCTs based on PICOS guidelines (population (individuals > 18 years old), the intervention (spirulina), the comparison (control or placebo group), the outcomes (systolic BP (SBP) and diastolic BP (DBP)), the study design (RCTs)), and PRISMA-checklist (Supporting Information, data S2). We evaluated the impact of spirulina on DBP and SBP. Conventional procedures were employed for analyzing publication bias, heterogeneity, and sensitivity. The GRADE criteria and the Cochrane assessment method were employed to evaluate the risk of bias (ROB) and certainty of evidence across the studies, respectively. The result shows spirulina consumption decreases SBP (WMD: -4.41 mmHg, 95% CI: -6.74 to -2.07, I-2 = 66.1%) and DBP (WMD: -2.84 mmHg, 95% CI: -4.65 to -1.03, I-2 = 62.3%). Subgroup analysis demonstrated SBP and DBP were still lower in individuals with >= 120 and >= 80 mmHg, hypertension (HTN) individuals, overweight individuals, age > 50 years, and > 8 weeks of intervention. Indeed, we do not observe publication bias, ROB, or interference studies in the overall results of BPs, and based on GRADE, our outcomes have moderate quality. Because of the low number of studies and participants, the dose-response and meta-regression are not significant. His study demonstrated spirulina intervention decreased SBP and DBP in HTN and overweight individuals, age > 50 years, and > 8 weeks of intervention. So, spirulina intake decreases BP and could be used in clinical practice. Furthermore, more and high-quality RCTs are needed to establish the clinical efficacy of the spirulina and determine cutoff spirulina interventions based on dose and duration.