Effect of cinnamon supplementation on blood pressure, oxidative stress, and inflammatory biomarkers in adults: An umbrella review of the meta-analyses of randomized controlled trials.

AIMS: Cinnamon has positive effects on markers of cardiometabolic health, including blood pressure (BP), oxidative stress, and inflammation. Despite the evidence accumulated from meta-analysis studies on the effects of cinnamon on these markers, the reported findings are still controversial. This umbrella review was conducted to evaluate the evidence and provide a definitive clarification.

DATA SYNTHESIS: We conducted a systematic search in four scientific databases, including PubMed, Scopus, Web of Science, and Embase electronic databases, up to March 2024 to identify systematic reviews and meta-analyses of randomized clinical trials investigating the impact of cinnamon on blood pressure, oxidative stress, and inflammation. The findings revealed that cinnamon might exert favorable effects on systolic blood pressure (SBP) (ES = -2.36 mmHg; 95% CI: 3.86, -1.40), diastolic blood pressure (DBP) (ES = -1.65 mmHg; 95% CI: 2.41, -0.90), total antioxidant capacity (TAC) (WMD = 0.34; 95% CI: 0.04, 0.64), and interleukin-6 (IL-6) (WMD = -1.48; 95% CI: 2.96, -0.01). However, the results did not show any significant effect of cinnamon on malondialdehyde (MDA) (WMD = -0.47; 95% CI: 0.99, 0.05), C-reactive protein (CRP) (WMD = -1.33; 95% CI: 2.66, 0.00), and intercellular adhesion molecule 1 (ICAM-1) (WMD= 1.53, 95% CI: 12.03, 15.10).

CONCLUSIONS: The results of the studies included in this umbrella review support the usefulness of cinnamon consumption in modulating BP as well as improving TAC and IL-6 in metabolic disorders. Due to the limited number of studies, clinical diversity, and other limitations, more high-quality studies must be conducted to provide more precise and comprehensive recommendations.

REGISTRATION NUMBER: PROSPERO, CRD42023487350.