Cinnamon
Cinnamomum spp.
Evidence Rating
Confidence Level
Traditions
Last Updated
Summary
Cinnamon bark has an EMA traditional use monograph for mild GI symptoms (cramping, flatulence). Its use for blood glucose management in type 2 diabetes, while widely marketed, remains clinically inconclusive based on systematic reviews and meta-analyses. A critical distinction exists between cassia cinnamon (high coumarin, more studied for glucose) and Ceylon cinnamon (low coumarin, safer for long-term use but less studied). The European BfR and EFSA have set a tolerable daily intake of 0.1 mg coumarin/kg body weight, which cassia cinnamon can easily exceed.
Drug Interactions
This herb has significant drug interactions. Do not use if you are taking medications without consulting a healthcare provider first. See detailed interaction information below.
Regulatory Status
| Regulatory Body | Status |
|---|---|
| Commission E (Germany) | âś“ Approved |
| ESCOP (European) | âś“ Approved |
| EMA/HMPC (EU) | âś“ Approved |
Metadata
| Field | Detail |
|---|---|
| Common Names (EN) | Cinnamon, cassia cinnamon, Ceylon cinnamon, true cinnamon |
| Common Names (DE) | Zimt, Ceylonzimt, Kassia, Cassiazimt, Chinesischer Zimt |
| Botanical Name | Cinnamomum verum J.S. Presl (syn. C. zeylanicum Nees) [Ceylon]; Cinnamomum cassia (L.) J. Presl (syn. C. aromaticum) [Cassia] |
| Plant Family | Lauraceae |
| Part Used | Bark (Cinnamomi cortex) |
| Evidence Quality Rating | Low-Medium — traditional use for GI well-supported; blood glucose evidence inconclusive; species confusion complicates interpretation |
Approved Indications
Commission E (Germany)
- Approved for loss of appetite, dyspeptic complaints (mild GI cramping, bloating, flatulence)
- Applies to Cinnamomum verum (Ceylon) bark
ESCOP
- Dyspeptic complaints
- Loss of appetite
EMA/HMPC
- Traditional use: Symptomatic relief of mild cramping/spasmodic gastrointestinal complaints, flatulence, and feeling of abdominal fullness
- Traditional use: Symptomatic relief of mild diarrhea associated with flatulence
- Monograph applies to Cinnamomum verum J.S. Presl cortex
- No approved indication for blood glucose management
Agreement/Disagreement Analysis
All European bodies agree on GI/dyspeptic use. None of them approve cinnamon for blood glucose management or diabetes, despite extensive consumer marketing for this purpose. The blood glucose indication exists primarily in the dietary supplement and popular health literature, not in regulatory approvals. This gap between marketed claims and regulatory approval is significant.
The Cassia vs. Ceylon Distinction (Critical)
Why It Matters
This is not a minor taxonomic detail — it has direct clinical safety implications.
| Parameter | Cassia Cinnamon (C. cassia) | Ceylon Cinnamon (C. verum/zeylanicum) |
|---|---|---|
| Origin | China, Vietnam, Indonesia | Sri Lanka, Madagascar, Seychelles |
| Coumarin content | 2,650-7,017 mg/kg (high) | 0.005-0.090 mg/g (trace/negligible) |
| Market share | ~95% of global cinnamon supply | ~5% of global supply; more expensive |
| Blood glucose studies | Most clinical trials used cassia | Very few studies use Ceylon |
| Long-term safety | Coumarin is hepatotoxic; TDI easily exceeded | Safe for long-term use |
| Flavor profile | Stronger, more pungent | Milder, more complex, sweeter |
| Essential oil | 1-4% (primarily cinnamaldehyde) | 0.5-2.5% (cinnamaldehyde + eugenol) |
Coumarin Safety Limits
- EFSA/BfR Tolerable Daily Intake (TDI): 0.1 mg coumarin per kg body weight
- For a 70 kg adult: maximum 7 mg coumarin/day
- 1 teaspoon (2.6 g) of cassia cinnamon may contain 6.9-18.2 mg coumarin — potentially exceeding the TDI in a single dose
- Ceylon cinnamon: Even large daily doses stay well below the TDI
- Implication: Anyone using cinnamon regularly for therapeutic purposes should use Ceylon cinnamon
Conditions Treated
Approved/Monographed
- Dyspepsia, mild GI cramping, flatulence
- Loss of appetite
- Mild diarrhea associated with flatulence
Researched but Not Approved
- Type 2 diabetes — blood glucose management (most researched non-approved indication)
- Dyslipidemia — lipid profile improvement
- Metabolic syndrome
- Polycystic ovary syndrome (PCOS) — insulin sensitizing
- Antimicrobial applications
Mechanism of Action
Key Active Compounds
- Cinnamaldehyde (60-75% of essential oil): Primary bioactive; antimicrobial, anti-inflammatory
- Eugenol (more prominent in Ceylon): Anti-inflammatory, antioxidant
- Coumarin (prominent in cassia): Hepatotoxic at high doses; anticoagulant properties
- Proanthocyanidins (type A polymers): Insulin-mimetic activity
- Cinnamic acid: Antioxidant
Proposed Blood Glucose Mechanisms
- Insulin-mimetic activity: Type A procyanidins may enhance insulin signaling
- Insulin receptor phosphorylation: Increased tyrosine phosphorylase activity
- GLUT4 translocation: May increase glucose transporter expression
- Alpha-glucosidase inhibition: May slow carbohydrate digestion
- Glycogen synthesis: May increase hepatic glycogen synthesis
GI Mechanisms (Traditional Indications)
- Carminative effect (reduces gas formation and bloating)
- Spasmolytic activity on GI smooth muscle
- Antimicrobial activity against GI pathogens
- Stimulation of digestive enzyme secretion
Clinical Evidence Summary
Blood Glucose (Type 2 Diabetes)
Positive Findings
- Khan et al. (2003): Landmark trial with cassia cinnamon (1, 3, or 6 g/day) in 60 type 2 diabetics
- Showed 18-29% reduction in fasting glucose
- Also reduced total cholesterol, LDL, and triglycerides
- This study sparked the entire cinnamon-diabetes research field
Negative/Inconclusive Findings
-
Cochrane Review (2012): Analyzed 10 clinical trials, 577 patients, C. cassia ~2 g/day for 4-16 weeks
- Effect on fasting plasma glucose: inconclusive
- No significant reduction in HbA1c or postprandial glucose
- Concluded: insufficient evidence to support cinnamon for diabetes
-
Meta-analysis (Allen et al., 2013): 10 RCTs, 543 patients
- Found modest reduction in fasting glucose (-0.49 mmol/L) and improvement in lipid profiles
- But high heterogeneity and low quality of included studies
Current Assessment
- Significant effects on fasting and 2-hour glucose found only in medium/high dose studies in persons with diabetes (not in non-diabetics or pre-diabetics)
- Most trials were of low methodological quality
- Species used was predominantly cassia (with its coumarin problem)
- Overall: evidence is inconclusive; long-term efficacy and safety trials are needed
- [UNCERTAIN] Whether cassia or Ceylon cinnamon is more effective for glucose — most data is from cassia
Ceylon Cinnamon Specifically
- Very few RCTs have used pure Ceylon cinnamon
- One RCT (2025) examined effects of C. zeylanicum on lipid profile and glucose — showed some beneficial effects but a single study is insufficient
- [NEEDS-RESEARCH] Head-to-head comparison of cassia vs. Ceylon for blood glucose
Dyspepsia and GI Symptoms
- Traditional use well-documented over centuries
- Limited modern clinical trial data specifically for cinnamon in dyspepsia
- Commission E and ESCOP approval based primarily on traditional evidence
European vs. US/Anglophone Consensus
| Dimension | European Position | US/Anglophone Position |
|---|---|---|
| Regulatory status | EMA traditional use (GI symptoms); no blood glucose approval | Dietary supplement; heavily marketed for blood sugar |
| Blood glucose claims | Not supported by regulatory bodies; evidence inconclusive | Widely marketed; some positive meta-analyses cited |
| Coumarin concern | BfR and EFSA actively warn about cassia coumarin; TDI established | Less regulatory attention to coumarin; most supplement products use cassia |
| Species awareness | Higher awareness of cassia vs. Ceylon distinction | Generally lower; most products are cassia |
| Clinical recommendations | Not recommended for diabetes management | Some integrative practitioners recommend; ADA does not endorse |
Safety Profile
Contraindications
- Allergy to cinnamon or Peru balsam (cross-reactivity)
- Liver disease: Particularly with cassia cinnamon (coumarin hepatotoxicity)
- Pregnancy: Not recommended in therapeutic doses (EMA: insufficient safety data)
Drug Interactions
- Antidiabetic agents: Potential additive hypoglycemic effect; monitor blood glucose
- Hepatotoxic drugs: Additive liver stress risk with cassia cinnamon (coumarin)
- Anticoagulants: Coumarin in cassia has anticoagulant properties; theoretical interaction with warfarin
- Tetracyclines: 1-2 g cinnamon may interfere with tetracycline absorption (EMA recommendation: do not use together)
Side Effects
- Common (mild): Bloating, dyspepsia, heartburn, nausea (dose-related)
- Uncommon: Allergic contact dermatitis (particularly with cinnamon oil)
- With cassia (high coumarin): Potential hepatotoxicity with prolonged high-dose use
- Cinnamon oil: Potential skin sensitizer; should not be used on young children or elderly
Pregnancy/Lactation
- Pregnancy: Not recommended at therapeutic doses; culinary amounts considered safe
- Lactation: Insufficient data; culinary use likely safe
Clinical Dosage
GI Symptoms (EMA Traditional Use)
- Powdered bark: 0.5-1 g, 2-4 times daily (max 4 g/day)
- Bark decoction: 0.5-1 g in 150 mL water, 2-3 times daily
- Tincture (1:5, ethanol 70%): 2-4 mL, 3 times daily
- Cinnamon oil: 0.05-0.2 g daily (in enteric-coated capsules)
Blood Glucose (Research Doses — Not Approved)
- Studies have used 1-6 g/day of cassia cinnamon powder
- Most common research dose: 1-2 g/day
- If using for glucose: strongly prefer Ceylon cinnamon to avoid coumarin toxicity
- Some standardized extracts (e.g., Cinnulin PF, water-soluble extract) remove coumarin
Duration
- GI symptoms: as needed; no specific time limit for Ceylon cinnamon
- If using cassia: limit duration due to coumarin accumulation
Key Products
- Various Ceylon cinnamon bark preparations (tea, capsules)
- Cinnulin PF (water-soluble cassia extract; coumarin reduced)
- Generic cinnamon bark capsules (usually cassia — check label)
Sources
- EMA/HMPC: Community Herbal Monograph on Cinnamomum verum J.S. Presl, cortex
- EMA/HMPC: Assessment Report on Cinnamomum verum cortex and corticis aetheroleum
- Commission E Monograph: Cinnamomi cortex
- ESCOP Monograph: Cinnamomi cortex
- Leach & Kumar (2012) “Cinnamon for diabetes mellitus” Cochrane Database of Systematic Reviews
- Allen et al. (2013) “Cinnamon Use in Type 2 Diabetes: An Updated Systematic Review and Meta-Analysis” PMC3767714
- BfR (German Institute for Risk Assessment): Coumarin in cinnamon assessment
- EFSA: Scientific Opinion on coumarin in food
- Ranasinghe et al. (2017) “Cinnamomum zeylanicum as a potential pharmaceutical agent for type-2 diabetes” Trials PMC5622575
- Khan et al. (2003) Diabetes Care — landmark cassia cinnamon trial
- NCCIH: Cinnamon (nccih.nih.gov)
Connections
- Turmeric Curcumin: Both studied for metabolic syndrome/blood glucose
- Fenugreek: Another herb with blood glucose claims; potentially stronger evidence
- Licorice: Both have traditional GI indications; both have significant safety considerations with prolonged use
- GI herbs module: Cinnamon’s approved indication overlaps with caraway, fennel, peppermint for GI symptoms
Related Herbs
Fenugreek
Trigonella foenum-graecum
Fenugreek seed is one of the oldest medicinal plants, approved by Commission E for internal use (loss of appetite) and external use (local inflammation as poultice). The ESCOP monograph additionally includes adjuvant therapy in diabetes and mild hypercholesterolemia. The EMA/HMPC recognizes traditional use for appetite loss (internal) and mild skin inflammations (external). Clinical evidence for blood glucose reduction in type 2 diabetes is positive in meta-analyses (significant reductions in fasting glucose and HbA1c) but based largely on low-quality trials. A distinctive maple-syrup odor in sweat and urine is a harmless but notable side effect.
Licorice
Glycyrrhiza glabra
Licorice root is one of the most important herbs in both European and Asian medicine, approved by Commission E and ESCOP for gastric/duodenal ulcers, gastritis, and respiratory catarrh. Its primary active compound glycyrrhizin (and its metabolite glycyrrhetinic acid) has potent anti-inflammatory and mucosal-protective effects but also causes mineralocorticoid-like adverse effects: sodium retention, potassium loss, and hypertension. This limits use to 4-6 weeks and a maximum glycyrrhizin intake of 100 mg/day. DGL (deglycyrrhizinated licorice) was developed to provide GI benefits without the hypertension risk and is effective for peptic ulcer symptoms when taken as chewable tablets.
Turmeric / Curcumin
Curcuma longa
Turmeric is approved in Europe as a traditional medicine for mild digestive complaints. Curcumin, its principal active compound, has potent anti-inflammatory and antioxidant activity in vitro but notoriously poor oral bioavailability. This has spawned a generation of enhanced formulations (Meriva, Longvida, Theracurmin) that dramatically improve absorption. Clinical evidence is most promising for osteoarthritis pain, with emerging data for IBD and metabolic syndrome. A rare but real hepatotoxicity signal has emerged, linked to the HLA-B*35:01 allele.