Abascal K, Yarnell E. The medicinal uses of cinnamon. Integrative Med. February/March 2010;9(1): 28-32.

"Cinnamon" is used to refer to several different trees and is associated with several Latin names, say the authors, adding that what could be called "true" cinnamon is Cinnamomum verum syn. C. zeylanicum. This article reviews the research of the medicinal uses of cinnamon (C. zeylanicum, C. verum, and C. cassia). N.B. So-called ‘cassia bark’ is Cinnamomum aromaticum syn. C. cassia (Chinese cinnamon).

Because of the confusion about the identity of cinnamon, correct identification and labeling of cinnamon should be required of any study or any commercial cinnamon product, say the authors. This should include not only the Latin name, but, for scientific studies, also a voucher specimen. They also opine that “very little of what passes for cinnamon in the marketplace, traditional medicine, or in modern studies is actually this true cinnamon”—and that cassia can be easily distinguished by its content of "0.45% coumarin and an almost complete absence of eugenol.”

Cinnamon has long been used in traditional Asian medicine and is most often combined with other herbs. It has been used for joint pain, heart palpitations, and dysmenorrhea. Ancient Egyptians used cinnamon as an embalming agent; it was brought to Europe from Asia as a cooking spice and medicine.¹ European herbalists prescribed it for dyspepsia, mild spasms, indigestion, loss of appetite, diarrhea, and uterine hemorrhaging.² American Eclectic physicians in the 19th century used cinnamon as a stimulant, tonic, stomachic, carminative, and astringent.³ They also used it to improve the flavors of other medicines.

The German Commission E approved the internal use of both C. verum and C. aromaticum to treat loss of appetite, dyspeptic complaints such as mild spastic conditions of the gastrointestinal tract, bloating, and flatulence.⁴

Cinnamon barks contain 1% to 2% volatile oils, with cinnamaldehyde as the main constituent, and also containing cinnamic acid, coumarin, tannins, cinncassiols, and melatonin. Cinnamon has strong antioxidant properties; its essential oil has reported antibacterial and antifungal properties in vitro. In animal studies, it has been shown to decrease smooth muscle contractions in the trachea and ileum, colon, and stomach. In a study of 54 human subjects, cinnamon tea increased total serum antioxidant status and decreased lipid peroxidation when compared with the consumption of water or regular tea.

The authors cite a study in which cinnamon bark showed a potential hypoglycemic action. Subsequent clinical trials have shown mixed results and are the subject of two recent systematic reviews.

The first review examined three "strong" to "good" clinical diabetes trials on cassia. The first trial reported reduced serum glucose, low-density lipoprotein cholesterol, and total cholesterol levels in 60 people with type 2 diabetes who took cassia daily for 40 days. The second study, in type 2 diabetes patients, reported a moderate effect of cassia on fasting glucose but no effect on hemoglobin A1c or lipid profiles. The third study reported no change in fasting glucose, insulin hemoglobin A1c, oral glucose tolerance, or lipid profile. The review pointed out that subjects in the first study had elevated baseline fasting glucose values, suggesting that cinnamon might be more effective in patients with poor glucose control. The second review analyzed five clinical trials of cassia given to patients with type 2 diabetes. None of the studies showed a significant change in hemoglobin A1c, fasting blood glucose, or lipid parameters. Thus, say the authors, "the benefit of cinnamon in diabetes remains unclear."

Regarding the antibacterial and antifungal properties of cinnamon, the authors cite a study that concluded that cinnamon was ineffective in eradicating Helicobacter pylori and another study in which a commercially available cinnamon product was reported to improve candidiasis. Also cited is a systematic review of studies investigating a combination formula that included cinnamon. The formula produced beneficial effects on angina with negligible adverse effects. In another recent review, cinnamon was an ingredient in many of the formulas that showed potential benefit in the treatment of endometriosis.

Addressing safety and drug interactions, the authors note that cinnamon bark is generally regarded as safe. Cinnamon-soaked toothpicks, cinnamon-flavored chewing gum, and raw cinnamon have been reported to cause sores, burns, and allergic reactions. A single case report cited by the authors linked cinnamon chewing gum to squamous cell carcinoma.

The authors list the average doses of the dried herb, essential oil, infusions, and tincture.

"Little clinical research has been done on this interesting plant, and that which has been done tends to ignore its traditional indications. As a result, much additional research remains to be conducted on this ancient spice and medicine."

―Shari Henson

References

¹Dugoua J, Seely D, Perri D, et al. From type 2 diabetes to antioxidant activity: a systematic review of the safety and efficacy of common and cassia cinnamon bark. Can J Physiol Pharmacol. 2007;85(9):837-847.

²Wynn SG, Fougere B. Veterinary Herbal Medicine. St. Louis, MO: Elsevier; 2007.

³Felter HW, Lloyd JU. King's American Dispensatory. Sandy, OR: Eclectic Institute; 1993.