Cinnamon Extract
Commonly used for
Metabolic Health
Where to Buy
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What is it? / Overview
Cinnamaldehyde and procyanidins inhibit carbohydrate-digesting enzymes, enhance insulin signaling, suppress hepatic glucose output, and slow gastric emptying -- lowering fasting and post-meal glucose. Evidence is genuinely mixed across meta-analyses (some find significant HbA1c benefit, an older Cochrane review found none), with very high heterogeneity across trials, largely because studies mix cassia and Ceylon species and doses.
How is it used? / Administration
Form: Cinnamomum verum/Ceylon (low coumarin, preferred for chronic use) vs. C. cassia (higher coumarin) -- species matters for both efficacy and liver safety
Typical dose studied: Up to 2 g/day of standardized extract was most consistently effective in meta-analysis; needs 10+ weeks for HbA1c effect
Timing: Daily, often divided with meals
The coumarin content difference between cassia (can run very high) and Ceylon (much lower) is the dominant safety consideration for regular, long-term use -- favor Ceylon/C. verum.
How well does it work? / Evidence
~ Moderate evidence
Who should avoid it?
Avoid with: NAFLD / MASLD — Fatty liver disease; End-stage liver disease / Cirrhosis
Interacts with: Insulin, sulfonylureas -- additive hypoglycemia risk; Other hepatotoxic drugs -- additive risk if using cassia specifically, which carries more coumarin
Already taking it? Reasonable to continue -- effects are real but modest and not a substitute for glycemic medication. Choose Ceylon (C. verum) over cassia for regular, chronic use given cassia's much higher coumarin content.
Research & references
de Moura SL et al. (2025). Effects of Cinnamon Supplementation on Metabolic Biomarkers in Individuals With Type 2 Diabetes: A Systematic Review and Meta-Analysis. Nutrition Reviews. Leach MJ, Kumar S (2012). Cinnamon for diabetes mellitus. Cochrane Database of Systematic Reviews.
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