NutriDex

The Supplement Research Compendium
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Cinnamon

Cinnamomum spp.

A common spice with small, inconsistent effects on blood sugar and lipids — and a real coumarin safety catch in the Cassia type.

Mixed evidence 🫀Heart & Metabolic

✚ Updated · How we grade evidence

Evidence tier
Mixed
Research weight
Citations
19 verified / 19
Classification
Heart & Metabolic
❝
What the evidence says. Conflicting results across studies; benefit uncertain.

What is Cinnamon?

Cinnamon (Cinnamomum spp.) is a heart and metabolic supplement used for may modestly lower fasting blood glucose in type 2 diabetes (meta-analyses report reductions of roughly 10–15 mg/dl), though effect sizes vary widely across trials. NutriDex grades the human evidence as Mixed. Cinnamon is a culinary bark spice from Cinnamomum species, sold mainly as cheaper Cassia (C. cassia/aromaticum) or the lower-coumarin Ceylon (C. verum, "true cinnamon"). Multiple meta-analyses suggest cinnamon supplementation can produce small reductions in fasting glucose, HbA1c and insulin resistance in people with type 2 diabetes, plus modest improvements in cholesterol, but results are inconsistent and heavily influenced by trial quality, dose, and cinnamon type. The lipid changes in pooled umbrella analyses are statistically borderline and likely too small to matter clinically on their own. Overall the human evidence is best described as mixed: a real but minor and unreliable metabolic effect that does not substitute for proven medications or lifestyle change. The most important practical issue is safety rather than efficacy: Cassia cinnamon is rich in coumarin, which can stress the liver and interact with anticoagulants at high or prolonged intakes. People interested in supplemental doses should favor Ceylon cinnamon and keep coumarin exposure within regulatory limits.

Purported Benefits

✓May modestly lower fasting blood glucose in type 2 diabetes (meta-analyses report reductions of roughly 10–15 mg/dL), though effect sizes vary widely across trials
✓Small reductions in HbA1c reported (about 0.1–0.6%), of uncertain clinical importance
✓Modest, statistically borderline improvements in total and LDL cholesterol and a small rise in HDL in pooled analyses; triglyceride effects are inconsistent
✓May slightly improve insulin resistance (HOMA-IR) in some diabetic and PCOS populations
✓Best signals appear at lower capsule doses (around 1.5–2 g/day or less); benefits are not robust enough to replace standard glucose- or lipid-lowering therapy

Evidence by outcome

The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.

OutcomeEvidenceEffectStudies
Lower fasting blood glucose (type 2 diabetes)Many meta-analyses show ~10-15 mg/dL reductions but effect sizes vary widely; NCCIH says evidence does not clearly support any condition. Mixed ↑ benefit · small 5
Reduced HbA1cPooled reductions of ~0.1-0.6% are small and of uncertain clinical importance. Mixed ↑ benefit · negligible 3
Improved lipid profile (TC/LDL/HDL)Umbrella analysis shows statistically significant but clinically trivial changes (~1 mg/dL); triglyceride effects inconsistent. Mixed ↔ mixed · negligible 3
Improved insulin resistance (HOMA-IR)Modest HOMA-IR reductions in diabetic and PCOS subgroups; PCOS meta-analysis based on only 5 small RCTs. Preliminary ↑ benefit · small 3
Coumarin hepatotoxicity (Cassia cinnamon)Cassia is coumarin-rich (TDI 0.1 mg/kg/day); high/prolonged intake can reversibly raise liver enzymes in sensitive people. Favor Ceylon. Moderate ⚠ risk 1

Dosing & Compounds

Typical Dose
1–2 g/day of cinnamon powder or standardized extract in divided doses; trials commonly use 1.5–6 g/day, but ≤2 g/day capsules show the most consistent metabolic signal. Prefer Ceylon (Cinnamomum verum) to limit coumarin exposure.
Active Compounds
Cinnamaldehyde (primary bioactive)Cinnamic acidCinnamyl acetateProcyanidin-type polyphenols (type-A polymers)EugenolCoumarin (high in Cassia, trace in Ceylon — a toxicity concern, not a benefit)

Safety & Cautions

Generally safe as a food/spice. The main concern with supplemental doses is coumarin, abundant in Cassia cinnamon (the common grocery type) and present only in traces in Ceylon (C. verum). Coumarin is hepatotoxic at sustained high intake: the EFSA/BfR tolerable daily intake is 0.1 mg/kg body weight (~7 mg/day for a 70 kg adult), and 1 tsp of Cassia (~5 mg) can approach or exceed this. High or prolonged Cassia use can raise liver enzymes or, in sensitive people, cause reversible hepatitis/jaundice — avoid with pre-existing liver disease. Coumarin and cinnamaldehyde may affect drug-metabolizing enzymes; cinnamon may increase bleeding risk with warfarin and other anticoagulants/antiplatelets and could alter blood glucose, so people on antidiabetic drugs should monitor for hypoglycemia and adjust under medical supervision. Use cautiously with hepatotoxic medications. Cinnamaldehyde can cause oral/skin irritation and allergic contact reactions. Pregnant and breastfeeding women should limit intake to culinary amounts and avoid concentrated supplements. Choose Ceylon cinnamon for regular supplemental use and discuss with a clinician if diabetic, on blood thinners, or having liver concerns. Educational only — always check with your doctor or pharmacist before combining Cinnamon with any medicine.

Cinnamon drug interactions

Known or theoretical interactions between Cinnamon and common medications — educational, not exhaustive. Always check with your doctor or pharmacist before combining Cinnamon with any medicine.

Monitor
Insulin & oral antidiabetics
Cassia cinnamon may modestly lower blood sugar, adding to diabetes medications.
May enhance insulin sensitivity and slow gastric emptying, additive with antidiabetics. NCCIH — Cinnamon

Key Studies ★ 19 studies

Systematic review Zhang 2025 ✓ Full text
Umbrella review of 21 meta-analyses (139 comparisons) found cinnamon significantly reduced fasting blood glucose (SMD -0.61; 95% CI -0.70 to -0.52), upgraded to 'highly suggestive' on reanalysis (SMD -0.74; 95% CI -0.99 to -0.48), with greater effects at >1.5 g/day and durations <=2 months.
Meta-analysis Moridpour 2024 ✓ PubMed
Updated dose-response meta-analysis of 24 RCTs in type 2 diabetes found cinnamon supplementation significantly lowered fasting blood sugar (SMD -1.32; 95% CI -1.77 to -0.87; p<0.001).
Meta-analysis Jafari 2025 (J Health Popul Nutr) ✓ PubMed
GRADE-assessed dose-response meta-analysis of 49 RCTs: cinnamon significantly lowered SBP (SMD -0.85), DBP (SMD -1.04), fasting glucose (SMD -1.28), HbA1c (SMD -0.71), HOMA-IR (SMD -0.54), LDL-C (SMD -0.71), total cholesterol (SMD -1.15), triglycerides (SMD -0.91) and CRP (SMD -0.78), and raised HDL-C (SMD +0.56).
Systematic review Gou 2025 (Front Nutr) ✓ PubMed
AMSTAR-2 umbrella review of 21 meta-analyses (139 comparisons): cinnamon supplementation significantly improves fasting glucose and lipid profiles, with larger effects in diabetes and metabolic syndrome; higher doses (>1.5 g/day) and shorter durations (<=2 months) enhanced benefit.
Meta-analysis Heshmati 2021 (J Food Biochem) ✓ PubMed
Meta-analysis of 5 RCTs in women with polycystic ovary syndrome: cinnamon significantly reduced insulin resistance (HOMA-IR SMD -0.84; 95% CI -1.52, -0.16, p=0.010) versus placebo.
umbrella meta-analysis 11 meta-analyses of RCTs (umbrella) ✓ PubMed
In type 2 diabetes and PCOS, cinnamon supplementation modestly reduced fasting plasma glucose (-10.93 mg/dL), insulin (-2.01 IU/mL), HOMA-IR (-0.61) and HbA1c (-0.10%), indicating small but consistent glycemic improvement.
systematic review and meta-analysis 28 RCTs, 3,054 patients with type 2 diabetes ✓ PubMed
Cinnamon lowered fasting blood glucose (WMD -15.26 mg/dL) and HbA1c (WMD -0.56%), with the strongest effects from capsules at ≤2 g/day, alongside improvements in lipids and BMI.
systematic review and meta-analysis Meta-analysis of RCTs, dose subgroups ✓ PubMed
Cinnamon had non-significant overall effects on total cholesterol and LDL but significantly reduced triglycerides (WMD -6.88 mg/dL); LDL and triglyceride benefits were limited to doses <500 mg/day.
umbrella meta-analysis 11 meta-analyses of RCTs (umbrella) ✓ PubMed
Cinnamon produced small, statistically significant improvements in total cholesterol (WMD -1.01 mg/dL), LDL (-0.82 mg/dL) and HDL (+0.47 mg/dL) but no significant effect on triglycerides, suggesting minimal clinical impact.
meta-analysis Meta-analysis of 8 RCTs, 582 adults ✓ PubMed
Cinnamon supplementation significantly reduced diastolic blood pressure (WMD -0.93 mmHg, 95% CI -1.55 to -0.32) but had no significant overall effect on systolic blood pressure (-0.61 mmHg), with a small systolic benefit only at durations >=8 weeks.
meta-analysis Dose-response meta-analysis of 12 RCTs, 786 adults ✓ PubMed
Cinnamon supplementation modestly reduced body weight (WMD -1.02 kg, 95% CI -1.66 to -0.38), BMI (-0.51 kg/m2) and waist circumference (-2.40 cm), with larger effects in adults <50 years or with baseline BMI >=30.
meta-analysis Systematic review and meta-analysis of RCTs (liver enzymes) ✓ PubMed
Cinnamon had no significant overall effect on ALT, AST or ALP, but significantly lowered ALT and AST in subgroups of type 2 diabetes patients and trials >12 weeks, suggesting benefit limited to metabolically impaired populations.
meta-analysis Meta-analysis of 6 RCTs, 285 adults ✓ PubMed
Cinnamon (Cinnamomum zeylanicum) supplementation significantly lowered serum C-reactive protein (WMD -0.81 mg/L, 95% CI -1.36 to -0.26), with larger anti-inflammatory effects when baseline CRP exceeded 3 mg/dL and in trials lasting over 12 weeks.
meta-analysis Systematic review and meta-analysis of RCTs (cardiometabolic inflammation/oxidative stress) ✓ PubMed
Cinnamon supplementation significantly reduced C-reactive protein and IL-6 and increased total antioxidant capacity in adults, supporting a modest anti-inflammatory and antioxidant effect.
rct Randomized double-blind crossover RCT, 18 adults with prediabetes and obesity ✓ PubMed
Cinnamon 4 g/day for 4 weeks significantly lowered 24-hour continuously monitored glucose concentrations and reduced postprandial glucose peaks versus placebo, indicating improved glycemic response in prediabetes.
rct Double-blind placebo-controlled RCT, 54 adults with prediabetes ✓ PubMed
Cinnamon 500 mg three times daily for 12 weeks kept fasting plasma glucose stable while it rose in placebo (5 mg/dL between-group difference) and significantly lowered 2-hour OGTT glucose and glucose AUC, improving glucose tolerance.
rct Prospective double-blind placebo-controlled RCT, 45 women with PCOS ✓ PubMed
Cinnamon 1.5 g/day improved menstrual cyclicity over 6 months (+0.23 cycles/month from baseline vs no change with placebo, P=.0085), with luteal progesterone confirming ovulatory menses, suggesting a reproductive benefit in PCOS.
government safety assessment Regulatory risk assessment (EFSA-aligned) ✓ Source
Coumarin TDI is 0.1 mg/kg body weight/day; Cassia cinnamon averages ~3,000 mg/kg coumarin (up to ~10,000) versus only trace levels in Ceylon, and high intake can reversibly raise liver enzymes or cause hepatitis in sensitive individuals.
government/authority NIH NCCIH evidence and safety statement ✓ Source
NCCIH concludes research does not clearly support cinnamon for any health condition including diabetes or weight loss; it is likely safe as a food spice but high-dose or prolonged cassia cinnamon use risks liver harm in susceptible people due to coumarin.
19 sources cited · 19 verified Search all studies on PubMed ↗

Common questions about Cinnamon

What is Cinnamon used for?

Cinnamon is most often taken for May modestly lower fasting blood glucose in type 2 diabetes (meta-analyses report reductions of roughly 10–15 mg/dL), though effect sizes vary widely across trials, Small reductions in HbA1c reported (about 0.1–0.6%), of uncertain clinical importance, Modest, statistically borderline improvements in total and LDL cholesterol and a small rise in HDL in pooled analyses; triglyceride effects are inconsistent, May slightly improve insulin resistance (HOMA-IR) in some diabetic and PCOS populations. A common spice with small, inconsistent effects on blood sugar and lipids — and a real coumarin safety catch in the Cassia type.

Does Cinnamon work — what does the evidence say?

Mixed evidence. Conflicting results across studies; benefit uncertain. Cinnamon is a culinary bark spice from Cinnamomum species, sold mainly as cheaper Cassia (C. cassia/aromaticum) or the lower-coumarin Ceylon (C. verum, "true cinnamon"). Multiple meta-analyses suggest cinnamon supplementation can produce small reductions in fasting glucose, HbA1c and insulin resistance in people with type 2 diabetes, plus modest improvements in cholesterol, but results are inconsistent and heavily influenced by trial quality, dose, and cinnamon type. The lipid changes in pooled umbrella analyses are statistically borderline and likely too small to matter clinically on their own. Overall the human evidence is best described as mixed: a real but minor and unreliable metabolic effect that does not substitute for proven medications or lifestyle change. The most important practical issue is safety rather than efficacy: Cassia cinnamon is rich in coumarin, which can stress the liver and interact with anticoagulants at high or prolonged intakes. People interested in supplemental doses should favor Ceylon cinnamon and keep coumarin exposure within regulatory limits.

What is the typical dose of Cinnamon?

1–2 g/day of cinnamon powder or standardized extract in divided doses; trials commonly use 1.5–6 g/day, but ≤2 g/day capsules show the most consistent metabolic signal. Prefer Ceylon (Cinnamomum verum) to limit coumarin exposure.

Is Cinnamon safe? Any cautions or side effects?

Generally safe as a food/spice. The main concern with supplemental doses is coumarin, abundant in Cassia cinnamon (the common grocery type) and present only in traces in Ceylon (C. verum). Coumarin is hepatotoxic at sustained high intake: the EFSA/BfR tolerable daily intake is 0.1 mg/kg body weight (~7 mg/day for a 70 kg adult), and 1 tsp of Cassia (~5 mg) can approach or exceed this. High or prolonged Cassia use can raise liver enzymes or, in sensitive people, cause reversible hepatitis/jaundice — avoid with pre-existing liver disease. Coumarin and cinnamaldehyde may affect drug-metabolizing enzymes; cinnamon may increase bleeding risk with warfarin and other anticoagulants/antiplatelets and could alter blood glucose, so people on antidiabetic drugs should monitor for hypoglycemia and adjust under medical supervision. Use cautiously with hepatotoxic medications. Cinnamaldehyde can cause oral/skin irritation and allergic contact reactions. Pregnant and breastfeeding women should limit intake to culinary amounts and avoid concentrated supplements. Choose Ceylon cinnamon for regular supplemental use and discuss with a clinician if diabetic, on blood thinners, or having liver concerns.

How many studies support Cinnamon?

NutriDex cites 19 sources for Cinnamon, graded "Mixed".

Does Cinnamon interact with any medications?

Yes — known or theoretical interactions include: Diabetes drugs (insulin, metformin) (monitor). This is educational and not exhaustive; always check with your doctor or pharmacist before combining Cinnamon with any medicine.

Cite this page
APA

Peh, D. (2026). Cinnamon (Cinnamomum spp.): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 26 Jun 2026, from https://nutridex.info/s/cinnamon

BibTeX
@misc{nutridex_cinnamon,
  author       = {Peh, Daryl},
  title        = {Cinnamon (Cinnamomum spp.): Benefits, Dosage, Side Effects \& Evidence},
  year         = {2026},
  howpublished = {NutriDex --- The Supplement Research Compendium},
  url          = {https://nutridex.info/s/cinnamon},
  note         = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-06-26}
}

For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.

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