What is cinnamon

Cinnamon (Cinnamomum zeylanicum and Cinnamon cassia) is a spice obtained from the inner bark of several tree species from the genus Cinnamomum that belongs to the Lauraceae family 1). Used as a spice for thousands of years, cinnamon comes from the bark of the cinnamon tree. Preparation of cinnamon involves stripping of the outer bark of the tree and letting the inner bark to dry and curl up into its customary cinnamon quills. Cinnamon is available in either its whole quill form (Cinnamon sticks) or as ground powder in the market 2). The aromatic bark of the various cinnamon species tree is used worldwide for culinary purposes, but is also used in Ayurvedic and traditional Chinese medicine for its hypoglycaemic, digestive, antispasmodic and antiseptic properties 3), 4). Overall, approximately 300 species have been identified among the cinnamon genus, with trees being scattered all over the world 5), 6). Cassia cinnamon, native to China, is the most common type sold in the United States and Canada. Ceylon cinnamon (Cinnamomum verum or Cinnamomum zeylanicum), native to Sri Lanka, is common in other countries and is known as “true” cinnamon 7). Indonesia (Cinnamomum burmanii) and China (Cinnamomum cassia) contribute 76% of the world’s production of cinnamon 8). Essential oils are made from the bark, leaves, or twigs of cassia cinnamon.

Cinnamon is mainly used in the aroma and essence industries due to its fragrance, which can be incorporated into different varieties of foodstuffs, perfumes, and medicinal products 9). The most important constituents of cinnamon are cinnamaldehyde and trans-cinnamaldehyde (Cin), which are present in the essential oil, thus contributing to the fragrance and to the various biological activities observed with cinnamon 10). A study on Cinnamomum osmophloeum (C. osmophloeum) indicated that the essential oil from cinnamon leaves contains a high level of trans-cinnamaldehyde (Cin). Consequently, Cinnamomum osmophloeum is also used as an alternative spice for cinnamon cassia 11). One of the major constituents of essential oil extracted from Cinnamomum zeylanicum named (E)-cinnamaldehyde has an antityrosinase activity 12), while cinnamaldehyde is the principal compound responsible for this activity 13).

Cinnamon bark contains procyanidins and catechins 14). The components of procyanidins include both procyanidin A-type and B-type linkages 15). These procyanidins extracted from cinnamon and berries also possess antioxidant activities 16).

Cinnamon has a long history as a traditional medicine, including for bronchitis. Today, some people use cinnamon as a dietary supplement for gastrointestinal problems, loss of appetite, and diabetes, among other conditions. Cinnamon is used in capsules, teas, and extracts.

However, studies done in humans don’t support using cinnamon for any health condition 17), 18), 19). A 2013 systematic review 20) of 10 randomized controlled clinical trials in people with type 1 or type 2 diabetes suggests that cinnamon doesn’t help to reduce levels of glucose or glycosylated hemoglobin A1c (HbA1c), a long-term measure of glucose (blood sugar) control. A 2012 Cochrane systematic review 21) of 10 randomized controlled trials involving a total of 577 participants found insufficient evidence to support the use of cinnamon for type 1 or type 2 diabetes. A product containing cinnamon, calcium, and zinc didn’t improve blood pressure in a small study of people with type 2 diabetes 22).

Traditional uses of cinnamon

In addition to being used as a spice and flavoring agent, cinnamon is also added to flavor chewing gums due to its mouth refreshing effects and ability to remove bad breath 23). Cinnamon can also improve the health of the colon, thereby reducing the risk of colon cancer 24).

Cinnamon is a coagulant and prevents bleeding 25). Cinnamon also increases the blood circulation in the uterus and advances tissue regeneration 26). This plant plays a vital role as a spice, but its essential oils and other constituents also have important activities, including antimicrobial 27), antifungal 28), antioxidant 29), and antidiabetic 30).

Cinnamon has been used as anti-inflammatory 31), antitermitic 32), nematicidal 33), mosquito larvicidal 34), insecticidal 35), antimycotic 36) and anticancer agent 37). Cinnamon has also been traditionally used as tooth powder and to treat toothaches, dental problems, oral microbiota, and bad breath 38). At present Cinnamon is sold as both a preventative and therapeutic supplement for many ailments including, metabolic syndrome, insulin resistance, type 2 diabetes, hyperlipidaemia and arthritis 39).

Note: All of the traditional uses outlined above have not be proven by well conducted scientific randomized clinical studies in human. Most of the traditional uses of cinnamon have all be done in laboratory test tubes and using animals as test subjects. We only list them here only to show what ailments and treatments cinnamon has been used traditionally and not because cinnamon has been proven to work in humans. More research are required before their benefits in human can be confirmed. Until larger and more rigorous clinical studies are available on the safety and efficacy of cinnamon as well as the feasibility of it as a component of integrative medicine, we recommend that patients continue to follow existing recommendations from their health care professionals.

Cinnamon nutrition facts

Almost every part of the cinnamon tree including the bark, leaves, flowers, fruits and roots, has some medicinal or culinary use. The volatile oils obtained from the bark, leaf, and root barks vary significantly in chemical composition, which suggests that they might vary in their pharmacological effects as well 40). The different parts of the plant possess the same array of hydrocarbons in varying proportions, with primary constituents such as; cinnamaldehyde (bark), eugenol (leaf) and camphor (root) 41). Thus cinnamon offers an array of different oils with diverse characteristics, each of which determines its’ value to the different industries. For example the root which has camphor as the main constitute, has minimal commercial value unlike the leaf and bark 42). It is this chemical diversity that is likely to be the reason for the wide-variety of medicinal benefits observed with cinnamon.

Table 1. Ground cinnamon nutrition content

[Source: United States Department of Agriculture Agricultural Research Service 43)]

Table 2. Chemical constituents of different parts of cinnamon

Part of the plantCompound
LeavesCinnamaldehyde: 1.00 to 5.00%
Eugenol: 70.00 to 95.00%

BarkCinnamaldehyde: 65.00 to 80.00%
Eugenol: 5.00 to 10.00%

Root barkCamphor: 60.00%

Fruittrans-Cinnamyl acetate (42.00 to 54.00%)
and caryophyllene (9.00 to 14.00%)

C. zeylanicum budsTerpene hydrocarbons: 78.00%
alpha-Bergamotene: 27.38%
alpha-Copaene: 23.05%
Oxygenated terpenoids: 9.00%

C. zeylanicum flowers(E)-Cinnamyl acetate: 41.98%
trans-alpha-Bergamotene: 7.97%
Caryophyllene oxide: 7.20%
[Source 44)]

Health benefits of cinnamon

Studies have been consistent in showing that diabetic patient adherence to current conventional treatment protocols are poor 45). Diabetic patients are 1.6 times more likely than non-diabetics to use a complementary and alternative medicine for a host of reasons 46). The worldwide trend for the use of complementary and alternative medicines in diabetes has increased with an overall prevalence ranging between 30-57 % 47).

Recent estimates show that over 80 % of people living in developing countries depend on complementary and alternative medicine for treatment of health conditions 48). More recently in 2013, Herman estimates the cost of Complementary and Integrative Medicine in the US to be 34 billion dollars 49).

Cinnamon has been a research interest in patients with diabetes since the 1990s 50). Various data from randomized clinical trials show conflicting results of the effects of cinnamon on glycemic and lipid parameters. Consumption of 1 to 1.2 g/d was associated with an increase in fasting plasma glucose levels 51), 52) and hemoglobin A1c levels 53), 54); however, others have reported reductions in glycemic parameters at doses between 1 to 6 g/d 55), 56), 57) and in hemoglobin A1c 58), 59), 60). The same conflict occurs in lipid parameters, at 1 g/d total cholesterol 61), LDL-“bad” Cholesterol 62), 63) and triglyceride levels were reported to increase 64), while HDL-“good” Cholesterol levels decreased 65), 66). Only 1 trial identified statistically significant increases in hemoglobin A1c and fasting plasma glucose levels; however, this trial was published only as a research brief, so many of the study characteristics were unclear 67). Based on currently available literature, cinnamon may have a beneficial effect on fasting plasma glucose, LDL-“bad” Cholesterol, HDL-“good” Cholesterol and triglyceride levels in patients with type 2 diabetes 68). But there is no statistically significant effect on hemoglobin A1c (HbA1c). Contrary to the finding of this study, a Cochrane Review 69) involving oral monopreparations of cinnamon (primarily Cinnamomum cassia) in tablet or capsule form, at an average daily dose of 2 g, for a mean period of 11 weeks, found that in people with type 1 or type 2 diabetes mellitus, orally administered cinnamon (Cinnamomum cassia) in tablet or capsule form, at a dose of 0.5 to 6 g daily for a period of four to 16 weeks, is no more effective than placebo at improving glycosylated haemoglobin A1c (HbA1c) or serum insulin levels. The effect of cinnamon on fasting and postprandial blood glucose levels is inconclusive 70).

In conclusion, cinnamon should not be used in place of conventional medical care or to delay seeking care if you have health problems. This is particularly true if you have diabetes.

Cinnamon side effects

Side effects of cinnamon have been poorly documented in humans, because most research focusing on safety and efficacy has been conducted either in test tubes or in animals. Potential side effects found in animal studies include liver toxicity that results from coumarin isolates found in cinnamon cassia bark, decreased platelet counts, increased the risk of bleeding and allergy/hypersensitivity to cinnamon 71).

Cassia cinnamon contains varying amounts of a chemical called coumarin, which might cause or worsen liver disease. In 2008, The European Food Safety Authority considered toxicity of coumarin, a significant component of cinnamon, and confirmed a maximum recommended tolerable daily intake (TDI) of 0.1 mg of coumarin per kg of body weight. Coumarin is known to cause liver and kidney damage in high concentrations and metabolic effect in humans with CYP2A6 polymorphism 72). Based on this assessment, the European Union set a guideline for maximum coumarin content in foodstuffs of 50 mg per kg of dough in seasonal foods, and 15 mg per kg in everyday baked foods 73).

According to the maximum recommended tolerable daily intake (TDI) of 0.1 mg of coumarin per kg of body weight, which is 7 mg of coumarin for a body weight of 70 kg.

  • Cinnamomum cassia (Chinese cinnamon) has 0.10 mg – 12.18 milligrams of coumarin per grams of cinnamon.
  • Cinnamomum verum (Ceylon cinnamon) has less than 0.10 milligrams of coumarin per grams of cinnamon.

In most cases, cassia cinnamon doesn’t have enough coumarin to make you sick. However, for some people, such as those with liver disease, taking a large amount of cinnamon (coumarin) might worsen their condition 74). These possible effects may be a concern for patients with impaired liver function, concurrent anticoagulant or antiplatelet therapy, patients on antilipidemic agents, and those who are known to be hypersensitive to cinnamon or its components. There are reports of nonimmunologic contact urticaria occurring in people coming into contact with cinnamon products 75); however, because no human studies have been conducted to test this theory, these concerns remain hypothetical. Isolated case reports of cinnamon-induced stomatitis venenata (inflammation of the mucous lining of any of the structures in the mouth) secondary to contact allergy have been reported with consumption of the herb as a flavouring agent 76). However, there have been no documented adverse effects associated with the oral administration of cinnamon extract in clinical studies to date.

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