Cinnamon

1. What Is Cinnamon?

Cinnamon is the dried inner bark of trees of the genus Cinnamomum. These trees belong to the laurel family. Two species are especially important in commerce: Ceylon cinnamon and Cassia cinnamon. In the past, cinnamon was considered a warming remedy and was used, among other things, for digestive complaints.

2. Where Is It Found, and What Is It Made From?

Cinnamon is used as a spice in foods and drinks. It also occurs in capsules, extracts and oils. The trees grow in tropical regions, for example in Sri Lanka, southern India, China, Indonesia and Vietnam. For production, young shoots are peeled, the bark is dried and rolled or ground. Extracts are made with water or alcohol, essential oil by steam distillation.

3. What Does Cinnamon Do? What Research Shows

Blood Glucose and Glucose Metabolism

Several reviews evaluated studies in which people with type 2 diabetes and women with polycystic ovary syndrome (a hormonal disorder of the ovaries) took cinnamon. Their fasting blood glucose fell 416192125. Long-term blood glucose also improved in several studies 41921253739. Post-meal blood glucose also fell 419. In prediabetes (a precursor of diabetes), values remained more stable with cinnamon than with placebo (sham treatment) 5052. One review and several individual studies found no difference in fasting blood glucose 27474951. Many reviews do not state the cinnamon type and form.

Blood Lipids

In adults with type 2 diabetes, PCOS or similar metabolic disorders, LDL cholesterol (the "bad" cholesterol) fell in several reviews 710192228. Total cholesterol and triglycerides (blood fats) also fell in several reviews 7101928. A review of ground Cassia cinnamon bark powder found no differences 32. The findings come predominantly from capsules whose cinnamon type was mostly not reported.

Body Weight and Body Composition

In several reviews, body mass index (ratio of weight to height) fell compared with the control groups 5929. Body weight also improved in several studies 592229. Waist circumference fell in several reviews 91928. One review also found a reduction in fat mass 9. Other studies showed no differences in weight, body mass index or waist circumference 173435364048. The findings come predominantly from capsules or powder, whose cinnamon type is often not stated.

Inflammatory and Oxidative Markers

In adults with metabolic disorders, type 2 diabetes, PCOS, rheumatoid arthritis (joint inflammation) and migraine, several studies found improvements in individual inflammation markers. CRP (an inflammation marker in the blood) improved in several studies 15193349. Malondialdehyde (an oxidation marker) also improved 193342. Antioxidant capacity (the body's protective capacity) also improved 2023263342. Other reviews and one study found no confirmed differences for some of these markers 232647. The findings come predominantly from cinnamon powder in capsules, the cinnamon type is mostly not reported.

Blood Pressure

Several reviews found a reduction in systolic blood pressure (the upper value) from cinnamon in adults, some with metabolic diseases or type 2 diabetes 121319232835. Diastolic blood pressure (the lower value) also fell in the same reviews 121319232835. Another review found no difference for systolic blood pressure, but a reduction for diastolic blood pressure 14. In incipient hypertension, blood pressure at the end of the study did not differ between cinnamon and placebo; only the upper daytime value fell more with cinnamon 51. In type 2 diabetes, one study found no difference 38. Cinnamon type and preparation form are mostly not reported.

Menstrual Pain

In menstrual pain, cinnamon in capsules reduced pain intensity more than placebo in one study 53. In another study, female students received dried figs, cinnamon or a sham treatment. The figs relieved pain more than cinnamon and placebo; whether cinnamon worked better than the sham treatment is not reported 41. The strength of evidence is moderate; the number of studies is small and the number of participants is limited. For several studies, precise information on the type, form and amount of cinnamon is missing.

Digestive Complaints

In cancer patients with nausea and vomiting during chemotherapy, the participants inhaled cinnamon oil. This relieved the symptoms more than a saline control 43. In diarrhea, an aqueous extract of Cassia cinnamon prolonged intestinal transit time and changed stool values and gut flora 44. The strength of evidence is low, the studies are small and examine different forms.

Other Investigations

In fatty liver, cinnamon lowered liver enzymes in one review 1; another review found no difference 31. A cinnamon bark nasal rinse improved quality of life in allergic rhinitis 3. In migraine, cinnamon powder reduced the frequency, intensity and duration of attacks 46. In rheumatoid arthritis, cinnamon powder reduced disease activity and pain 49. In PCOS, cinnamon extract improved the regularity of the menstrual cycle 16. The findings come predominantly from small studies, several without information on cinnamon type, form and amount.

4. How Was Cinnamon Taken in the Studies?

The studies tested cinnamon predominantly as a capsule or powder. In addition, there were aqueous or alcoholic bark extracts, cinnamon oil as well as 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 in only some of the studies. Many reviews do not state the cinnamon type and the preparation form.

5. Is Cinnamon Safe? Side Effects in the Studies

The studies predominantly report good tolerability of cinnamon preparations. A review found no statistically confirmed side effects compared with placebo, regardless of amount and duration 30. Individual studies report skin rash with cinnamon oil 45, digestive complaints with discontinuation in two participants 55, and oral mucosal changes from cinnamon-containing chewing gum and cinnamon-containing candies 54. In a study in prediabetes, no serious adverse events occurred 52.

All details with tables and sources: full expert page on Cinnamon