Strongest evidence
The highest-quality research supports cinnamon for reducing fasting blood glucose (5 studies, 4 beneficial, high evidence) and hemoglobin A1c (6 studies, 4 beneficial, moderate evidence) in adults with type 2 diabetes. For fasting glucose, effect sizes ranged from moderate to large, while for HbA1c, doses ≤2 g/day showed moderate reductions. Cinnamon also shows moderate evidence for lowering triglycerides (4 of 5 studies beneficial) and blood cholesterol (3 of 4 studies beneficial), with effective doses of 600 mg–2 g/day over 4–12 weeks.
Mixed or weaker evidence
Evidence is weaker for LDL reduction (3 of 3 studies beneficial, but small sample sizes and preliminary conclusions) and for blood glucose in PCOS (4 of 4 studies, low evidence strength). For body mass index and body weight, the evidence is low and predominantly neutral – only 1 of 3 studies showed benefit for BMI, and none of the weight studies reached statistical significance.
Effective dose patterns
Across multiple outcomes (HbA1c, triglycerides, cholesterol, BMI), the most consistent effective dose range is ≤2 g/day, with some studies also using 600 mg/day. Doses are not always reported, and the median study duration is around 8–12 weeks, suggesting that effects may require at least 2 months of supplementation.
Population insights
The vast majority of studies focus on clinical populations – primarily adults with type 2 diabetes, and to a lesser extent individuals with dyslipidemia or PCOS. Generalizability to healthy individuals is unclear, as most research was conducted in metabolically compromised groups.
Notable caveats
Many meta-analyses exhibit high heterogeneity (I² up to 92%), indicating inconsistent results across studies. Several trials combined cinnamon with other interventions (e.g., berberine), making it difficult to isolate cinnamon’s specific effect. Publication bias is a concern for outcomes with overwhelmingly positive but small evidence bases (e.g., LDL, blood glucose in PCOS). Only a minority of studies report study duration, limiting confidence in the time course of effects.