Cinnamon

We evaluated 138 human studies on Cinnamon, including 44 randomised controlled trials and 38 meta-analyses or systematic reviews; the controlled studies include 3,313 participants in total. As of 23 October 2026.

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1. What Is Cinnamon? Occurrence, Origin and Forms

Cinnamon is the dried inner bark of trees of the genus Cinnamomum in the laurel family (Lauraceae) and is used worldwide as a spice. Two species dominate trade: Ceylon cinnamon (Cinnamomum verum) and cassia (Cinnamomum cassia). Traditionally, cinnamon is regarded as a warming remedy that was used, among other things, for digestive complaints.

The trees grow in tropical regions, including Sri Lanka, southern India, China, Indonesia and Vietnam. Cinnamon is used as a spice in foods and drinks as well as in capsules, extracts and oils.

For harvesting, young shoots are peeled, and the bark is dried and rolled into quills or ground. Extracts are made with water or alcohol, and the essential oil by steam distillation. In human studies, bark powder in capsules, aqueous and alcoholic extracts, and the essential oil are the forms mainly examined.

Forms and Preparations Studied

• Ceylon cinnamon (Cinnamomum verum) as bark or powder
• Cassia cinnamon (Cinnamomum cassia) as bark or powder
• Aqueous or alcoholic bark extract, usually in capsule form
• Essential oil from the bark
• Cinnamon infusion or cinnamon tea
• Cinnamon as an ingredient in fortified foods

Not covered on this page:

• Isolated cinnamaldehyde or cinnamic acid as a single substance; a study on it is not a study on cinnamon.
• Other spices such as clove, nutmeg or ginger.
• Leaves and flowers of other Cinnamomum species traded as spice leaf or bud.

2. What Does Cinnamon Do? Results by Area

How to read the table: counted are human studies whose results concern the area. “High” means at least one meta-analysis and two controlled studies showing improvement, or at least three controlled studies of which three quarters show improvement, with at least 300 participants in total. “Moderate” means at least two controlled studies showing improvement, as a majority, or one meta-analysis alongside controlled studies. “Low” means one controlled study showing improvement. Where an area has no controlled study, the strength of evidence is at most “low” (result “reviews only” or “observational data only”). Everything else is “unclear”. A study counts as showing improvement when at least half of its outcomes in this area improved. Reviews of combination products do not count as meta-analyses; results that only describe side effects or shares of users do not count as an effect. The same study is counted only once.

3. What the Studies Show in Detail

Cinnamon, Blood Glucose and Glucose Metabolism: Human Studies

In adults with type 2 diabetes and in women with polycystic ovary syndrome, cinnamon lowered fasting blood sugar in several meta-analyses 419242636. Long-term blood sugar also improved in several controlled studies and meta-analyses 42426365862. Blood sugar after eating fell in meta-analyses 424. With a single test meal, cinnamon flattened the rise in blood sugar compared with the control meal 9496. In prediabetes, continuously measured glucose levels were lower with cinnamon than with placebo 97, and fasting blood sugar did not rise with cinnamon, but did with placebo 99. One meta-analysis and several randomized studies found no difference in fasting blood sugar 38879298. For HbA1c, insulin or insulin resistance, individual meta-analyses and one randomized study found no difference 63847525387. A single cinnamon infusion did not significantly change capillary glucose in healthy students shortly after drinking 61. The strength of evidence is high, but the results are mixed; many reviews do not state the cinnamon type and form, and the amounts tested differ; results for one form cannot be transferred to another. It remains open which cinnamon type and which preparation at which amount has the greatest benefit.

Further studies in this area: 28 30 31 32 34 36 38 39 41 44 46 47 50 52 53 54 55 56 57 58 61 62 63 64 67 68 72 73 77 87 89 90 92 94 96 97 98 99 100 104 105 108 112 116 117 118 119 120 121 122 125 128 129 130 131 132 133 135 136 137

Cinnamon and Blood Lipids: Human Studies

In adults with type 2 diabetes and related metabolic disorders, LDL cholesterol fell in several meta-analyses 710242841. Total cholesterol and triglycerides also fell in several meta-analyses 7102441; one meta-analysis found a reduction only in triglycerides and total cholesterol 11, another only in triglycerides 27. For HDL cholesterol, some meta-analyses found an increase 243841, others no difference 671127. A meta-analysis on ground Cassia cinnamon bark powder found no differences in total cholesterol, triglycerides, LDL and HDL 47, and a further review without stating type and form likewise found no differences in blood lipid levels 52. Individual randomized studies found no difference compared with placebo in LDL cholesterol 6064 and in the lipid profile 8992; after a cinnamon test meal, triglycerides did not differ from the control meal 94. The findings come predominantly from supplements in capsule form, whose cinnamon type was mostly not reported. The strength of evidence of the reviews is high, but the nonspecific statement of cinnamon type, form and amount as well as the short study durations limit the transferability to concrete preparations.

Further studies in this area: 25 27 28 30 32 37 38 39 41 46 47 50 52 58 60 64 66 68 71 77 89 92 93 94 97 98 100 112 122 127 129 132 133

Cinnamon, Body Weight and Body Composition: Human Studies

In several meta-analyses, body mass index fell compared with the control groups 5942. Body weight also improved in several studies 592842. Waist circumference fell in several meta-analyses 92441 and in one randomized study in migraine 84; the waist-to-hip ratio fell in one meta-analysis and in the same study 584. One meta-analysis also found a reduction in fat mass 9. This is contrasted by several studies that showed no difference in weight, body mass index or waist circumference 205051536588; body adiposity index and neck circumference also did not differ in one randomized study 65. The findings come predominantly from cinnamon supplements in capsule or powder form, whose cinnamon type is often not stated. In one randomized study in type 2 diabetes, cinnamon added to black tea showed no confirmed difference in body measurements 59. The strength of evidence is high, but the results are mixed; preparations, forms and participant groups differ, and the cinnamon type is often missing.

Further studies in this area: 46 50 51 53 59 65 72 73 82 88 89 100 103 112 122 132

Cinnamon, Inflammatory and Oxidative Markers: Human Studies

In adults with metabolic disorders, type 2 diabetes, PCOS, rheumatoid arthritis and migraine, several controlled studies and meta-analyses found improvements in individual inflammation and oxidation markers. For CRP, improvements were shown in several controlled studies and meta-analyses 17244892. Malondialdehyde improved in several controlled studies and meta-analyses 244871. Antioxidant capacity improved in several controlled studies and meta-analyses 2529374871. Interleukin-6 fell borderline significantly in several meta-analyses and in one randomized study in migraine compared with placebo 29374883. Reviews of meta-analyses, by contrast, found no confirmed difference for malondialdehyde and CRP 2937, and one randomized study in type 2 diabetes found no difference for malondialdehyde and antioxidant capacity 87. The findings come predominantly from cinnamon powder in capsules, as well as from bark extracts and unspecified cinnamon supplements; the cinnamon type (Ceylon or Cassia) and the amount tested are mostly not reported. After a cinnamon test meal, interleukin-6 did not differ from the control meal 94. The strength of evidence is high, but most individual controlled studies found no difference; it remains open which preparation reliably influences which inflammation markers.

Further studies in this area: 37 40 46 48 49 59 67 71 72 83 85 86 87 92 94 121 122 132 133

Cinnamon and Blood Pressure: Human Studies

Several meta-analyses found a reduction in systolic blood pressure from cinnamon in adults, some with metabolic diseases or type 2 diabetes 131424294151. For diastolic blood pressure, the same meta-analyses also showed a reduction 131424294151. Another meta-analysis found no overall difference for systolic blood pressure, but a reduction for diastolic blood pressure 15. In early-stage hypertension, blood pressure at the end of the study did not differ between cinnamon and placebo; only the daytime change in the systolic value was greater with cinnamon 98. In type 2 diabetes, a randomized study with cinnamon added to black tea found no difference 59. In the meta-analyses and reviews, cinnamon type and preparation form are mostly not reported, so it remains open whether the findings apply to Ceylon cinnamon, Cassia cinnamon, powder or extract; the amount tested is also not stated there.

Further studies in this area: 59 92 98 112 126

Cinnamon and Menstrual Pain: Human Studies

In menstrual pain, cinnamon in capsules reduced pain intensity more than placebo in a randomized study 102. In a randomized study with female students, dried figs relieved pain intensity and duration more than cinnamon and placebo; a benefit of cinnamon over placebo is not reported 70. The strength of evidence is moderate; the number of controlled studies is small, the number of participants is limited, and for several studies precise information on the type, form and amount of cinnamon tested is missing. It remains open whether the findings can be transferred to a specific cinnamon type or preparation.

Cinnamon and Digestive Complaints: Human Studies

In cancer patients with nausea and vomiting during chemotherapy, inhaling cinnamon oil relieved the symptoms more than a saline control 74. In diarrheal symptoms, an aqueous extract of Cassia cinnamon prolonged intestinal transit time and changed stool values and gut flora compared with placebo 75. In functional dyspepsia, symptoms improved with cinnamon oil capsules and with a sesame oil placebo, with no difference between the groups 78. The strength of evidence is low, the studies are small and examine different forms, so findings cannot be transferred to other preparations.

Cinnamon: Further Outcomes in Studies

In a network meta-analysis, cinnamon lowered liver enzymes in fatty liver (MASLD/MASH) 1; a meta-analysis in adults found no overall difference in liver enzymes 45. A cinnamon bark nasal rinse improved quality of life in allergic rhinitis 3, and a systematic review describes lower leptin and visfatin levels 16. In migraine, cinnamon powder reduced the frequency, intensity and duration of attacks compared with placebo 83. In women with rheumatoid arthritis, cinnamon powder reduced disease activity, pain and the number of painful and swollen joints compared with placebo 92. In women with polycystic ovary syndrome, cinnamon extract improved the regularity of the menstrual cycle in a meta-analysis 19. A systematic review describes favorable findings on ovarian function in women with polycystic ovary syndrome, which further studies should confirm 46. In women with polycystic ovary syndrome, cinnamon lowered testosterone levels similarly to metformin 73. DHEA levels remained without difference 2073. Adiponectin remained without difference 16. The findings come predominantly from small studies, some with incomplete reporting, several without information on cinnamon type, form and amount. Since findings for one form cannot be transferred to another, the type, preparation and amount tested remain open for most of these outcomes.

Further studies in this area: 43 45 46 63 69 70 73 74 76 79 80 81 82 83 88 89 91 92 95 101 106 107 109 110 111 113 114 115 118 121 123 124 134

4. How Is Cinnamon Dosed? Preparation, Dose and Duration in Studies

The studies tested cinnamon predominantly as a capsule or powder, and also as an aqueous or alcoholic bark extract, as cinnamon oil and as a cinnamon infusion or cinnamon tea. Individual investigations used cinnamon as an ingredient in fortified foods or as a nasal rinse. Ceylon cinnamon and Cassia cinnamon were explicitly distinguished only in some of the studies; many reviews do not name the cinnamon type and the preparation form.

5. Is Cinnamon Safe? Side Effects in Studies

The studies predominantly report good tolerability of cinnamon preparations. An overview of meta-analyses found no significant toxic or side effects compared with placebo, regardless of dose and duration 43. Individual studies report skin rash with cinnamon oil 78, dyspepsia with discontinuation in two participants 112, and oral mucosal changes from cinnamon-containing chewing gum and cinnamon-containing candies 109; in a study in prediabetes, no serious adverse events occurred 99.

6. What Remains Open: Limits of the Evidence

• Many reviews name neither the cinnamon type (Ceylon or Cassia) nor the preparation form, so it remains open for which form the findings apply.
• The amounts tested differ between the studies, and results for one form cannot be transferred to another.
• Some of the studies investigated combination preparations with other active substances, whose results cannot be attributed to cinnamon alone.
• The study durations are predominantly short, and several investigations are small or incompletely reported.
• For menstrual pain and digestive complaints, the number of controlled studies is small.

7. Bottom Line: What Is Established About Cinnamon

Cinnamon is the dried inner bark of trees of the genus Cinnamomum, traded mainly as Ceylon cinnamon and Cassia cinnamon. Human studies show improvements in fasting blood sugar, long-term blood sugar and postprandial glucose as well as in body mass index, body weight, waist circumference and blood pressure in adults with type 2 diabetes, PCOS and related metabolic disorders. Several meta-analyses also found improvements in LDL cholesterol, total cholesterol and triglycerides, while other studies showed no differences. For inflammation and oxidation markers, the findings are mixed: improvements in individual markers stand alongside studies with no difference.

The strength of evidence is high for blood sugar, blood lipids, inflammation markers, body weight and blood pressure, moderate for menstrual pain and low for digestive complaints. However, the results are clearly favorable only for blood pressure; for blood sugar, blood lipids and weight they are mixed, and for inflammation markers most individual studies found no difference. It is crucial that many reviews do not report the cinnamon type, form and amount tested, and some of the studies investigated mixed preparations with other active ingredients. Results therefore apply only to the form and preparation tested in each case.