INTRODUCTION

Cinnamomum verum is a small-to-moderate, bushy, evergreen tree that grows to about 52 feet (16 m) in height with smooth, pinkish bark.^1-3 Fresh leaf growth, called a flush, begins in the monsoon season (June through September) and varies from green to deep purple.² The fragrant flowers are small, pale yellowish-green, and are attractive to insects, particularly bees. Cinnamomum verum is native to Sri Lanka and southern India, from sea level to 2,953 feet (900 m) and is cultivated in Sri Lanka, the coastal regions of India (in the Western Ghats and adjoining hills), parts of Africa (Madagascar and the Seychelles), Indonesia (Java), South America (Brazil), and the West Indies.^1,3 This species is also cultivated in southeastern China’s Guangdong Province and neighboring Taiwan.⁴ Commercial plant material comes primarily from Sri Lanka, India, Malaysia, Madagascar, and the Seychelles.¹

The main part of the tree used commercially is the dried bark, separated from the cork and underlying parenchyma (primary tissue that forms the greater part of the plant and fills the gaps between more specialized cells) of young branches and semi-hard shoots.^1,2 For commercial cultivation, the shoots are coppiced (pruned almost level with the ground) on a regular basis to encourage dense, shrubby growth that results in more harvestable plant material.²

The International Organization for Standardization (ISO) provides quality specifications for 4 main commercial grades of Sri Lankan type cinnamon known as quills, quillings, featherings, and chips. Within the quills grade alone, there are 13 different commercial designations of distinct qualities. There are also 4 commercial designations for grades of Seychelles type and Madagascan type cinnamon: whole tubes, pieces of scraped bark, pieces of unscraped bark, and chips/flakes of unscraped bark.⁵

Processed cinnamon bark products include Ceylon-type cinnamon bark oil (volatile oil obtained by steam distillation of the dried inner bark of the clipped shrub or shoots), liquid extract (ratio of dried bark to extraction solvent 1:1; ethanol 70% V/V), tincture (1:5; ethanol 70% V/V), various aqueous or aqueous-alcoholic dried extracts, and supercritical carbon dioxide (CO2) soft extracts. Cinnamon leaf oil is also used, but to a much lesser extent.

HISTORY AND CULTURAL SIGNIFICANCE

The species name verum refers to it being the “true” cinnamon. The synonym, or former Latin binomial, C. zeylanicum, refers to the species originating in Ceylon, what is now Sri Lanka, the island nation at the southern tip of India. Many Cinnamomum species are referred to as cinnamon, and most Western countries don’t differentiate much between cinnamon and cassia or Chinese cinnamon (C. aromaticum syn. C. cassia). The ISO 6538 defines commercial grades of 3 types of cassia bark, Chinese type cassia (C. aromaticum), Indonesian type cassia (C. burmanii), and Vietnamese type cassia (C. loureirii), with a separate ISO standard for cinnamon bark (C. verum).⁶ The American Spice Trade Association allows both cassia and cinnamon bark to be labeled and sold as cinnamon for seasoning and spice purposes in food products.⁷ However, if cinnamon is used as a dietary supplement ingredient, US Food and Drug Administration (FDA) labeling regulations require use of the common name consistent with the name standardized in the American Herbal Products Association’s Herbs of Commerce, 2^nd ed., which does differentiate between cassia and cinnamon.⁸ For purposes of this article, however, the common name cinnamon refers to C. verum. Other species will be identified by Latin binomial.

Cinnamon played a major role in colonial expansion.¹⁰ In 1536, Portugal invaded what was then Ceylon to monopolize the cinnamon trade. By 1770, the Dutch were cultivating cinnamon and the Dutch East India company dominated the world trade in cinnamon from 1796 to 1833.

The major commercial use of cinnamon is as a spice to flavor food.⁹ It can be found in curry and tea blends, baked goods, beverages, canned fruit, confections, desserts, pickles, liqueurs, marinades, meats, sauces, soups, and chewing gum. In Spanish-speaking countries cinnamon (canela) is popular in chocolate and it is one of the ingredients in Chinese 5-spice blend. Cinnamon, along with other spices and fruit, is used in making mulled wine which is often used as an apéritif to aid digestion.

Cinnamon bark essential oil is used in the food, perfume, and pharmaceutical industries. It has replaced ground cinnamon in the food industry in large part, as it can provide a uniform flavor to confectionery, meat, and other processed foods.⁹ It is also added to food products for its antimicrobial and antioxidant benefits that help retard spoilage. Cinnamon leaf oil, being high in eugenol (65-92%) and cheaper than bark oil, is often used in the food industry to flavor confections and to prepare synthetic vanillin. Cinnamon bark oleoresin — an extremely concentrated, dark brown, viscous liquid — is obtained by solvent extraction and is used for flavoring cakes and confections.

Due to its irritant and skin-sensitizing properties, cinnamon bark oil is used minimally in the perfume industry to add a musky, woody undertone.⁹ It is also a fragrance ingredient in soaps, toothpastes, and mouthwashes. Cinnamon leaf oil is also employed as a fragrance and germicidal ingredient in soaps.^9,11

Cinnamon [bark and its oil] is employed in the pharmaceutical industry as an ingredient in products used for asthma, colds, and coughs for its fever-reducing and expectorant properties.⁹ It is also an ingredient in medicines for treating bad breath, diarrhea, flatulence, gastric distress, impotence, typhoid fever, nausea, and vomiting.

Part of cinnamon’s commercial popularity lies in its ability to both enhance and suppress flavor.⁹ When added to foods containing sugar, cinnamon exerts a synergistic effect and its aroma enhances the sensation of sweetness. Alternatively, cinnamon can help mask undesirable flavors and odors in foods and drugs.

Cinnamon bark oil is antibacterial, antifungal, antimicrobial, an antioxidant, antiviral, and larvicidal.^1,9,11 It has been employed for several millennia in traditional Eastern and Western medicine for anorexia, bloating, dyspepsia with nausea, flatulent colic, and spastic conditions of the gastrointestinal tract.¹ In his classic CRC Handbook of Medicinal Plants, Dr. James Duke lists it as a folk remedy for a wide range of conditions: “amenorrhea, arthritis, asthma, bronchitis, cancer, cholera, coronary problems, cough, diarrhea, dysentery, dyspepsia, fever, fistula, lumbago, lungs, menorrhagia, nephritis, phthisis [pulmonary tuberculosis or other disease that causes wasting of the body], prolapse, proctosis, psoriasis, spasms, tumors, vaginitis, warts, and wens [sebaceous or epidermal inclusion cysts].”¹¹ Additional folk medicine uses include dyspnoea (shortness of breath or labored breathing caused by serious disease of the airways, heart, or lungs), eye inflammation, “frigidity,” impotence, neuralgia, rheumatism, toothache, and wounds.³ It also has been used to alleviate tongue paralysis, as well as externally to relieve poisonous insect stings and acne.⁹ In Indian Ayurvedic and Unani medicine, cinnamon bark oil (dārusitā taila) is used as a single drug to treat flatulence, impaired digestion and metabolism, intestinal tract inflammation, peptic ulcer, vomiting, hemorrhoids, failure of penile erection, worm infestation, dryness of mouth, thirst, rhinitis/sinusitis, acute pain of nervine origin, blood disorders, tubercular ulcers, scorpion bite, and toothache.¹² Cinnamon leaf oil has been used externally for rheumatism and inflammation.⁹

Also in the Ayurvedic system of medicine, the powdered inner bark (tvak) is indicated for treating throat and mouth diseases, dryness of mouth, thirst, urinary bladder diseases, hemorrhoids, worm infestation, rhinitis/sinusitis, and heart disease.¹³ In Siddha medicine, the powdered inner stem bark (ilavankap pattai) is used for treating all types of poisons and toxins, dysentery, painful gastrointestinal disorders with indigestion, flatulence, and wheezing.¹⁴ In Unani medicine, the dried inner bark (darchini) is used for complete suppression of urine formation and excretion, sexual debility, the fungal infection tinea versicolor (Pityriasis versicolor), bad breath, and asthma.¹⁵

In 1990, oral use of cinnamon bark (essential oil, tea infusion, or tincture) was approved by the German Commission E for loss of appetite and dyspeptic complaints such as mild, spastic condition of the gastrointestinal tract, bloating, and flatulence.¹⁶ The European Scientific Cooperative on Phytotherapy (ESCOP) included diarrhea as one of the conditions cinnamon bark can treat.¹⁷

As in many parts of the world, medicinal plants play an important role in primary healthcare in Palestine. Of 1,883 Palestinian patients with diabetes interviewed regarding the use of herbs for treating their condition, 105 (10.8%) reported using C. verum in a dosage form raw or as a decoction or infusion.¹⁸

CURRENT AUTHORIZED USES IN COSMETICS, FOODS, AND MEDICINES

In 2011, the European Medicines Agency (EMA) published final labeling standards monographs on cinnamon bark and cinnamon bark oil, which supersede existing monographs of EU national authorities for the registration and marketing authorization of traditional herbal medicinal products that contain cinnamon. The authorized traditional medicinal uses for cinnamon bark (as herbal tea, liquid extract [1:1], or tincture [1:5]) are (1) for symptomatic treatment of mild, spasmodic gastrointestinal complaints including bloating and flatulence; and (2) for symptomatic treatment of mild diarrhea.19 The essential oil in liquid dosage forms for oral use is authorized for same as cinnamon bark use (1).20 A prerequisite of product registration is that the quality complies with the corresponding quality standards monographs of the European Pharmacopoeia (e.g., Cinnamon PhEur, Cinnamon Tincture PhEur, or Ceylon Cinnamon Bark Oil PhEur).21 Concerning the use of cinnamon in cosmetic products in the EU, the European Commission Health and Consumers Directorate lists “Cinnamomum Zeylanicum Bark Powder” (obtained from the dried, ground bark of C. zeylanicum) for use as a skin conditioning ingredient while “Cinnamomum Zeylanicum Bark Oil” (volatile oil expressed from bark of C. zeylanicum, containing cinnamaldehyde [50-60%], eugenol [4-8%], and phellandrene) is listed for masking, perfuming, and tonic functions. “Cinnamomum Zeylanicum Bark Extract” (obtained from dried bark of C. zeylanicum) is listed for antimicrobial, antioxidant, astringent, emollient, humectant, perfuming, skin-conditioning, and skin-protecting functions.²²

In the United States, cinnamon bark is regulated as a food additive and as a dietary supplement component. Both Ceylon cinnamon bark and leaf are listed as GRAS (Generally Recognized as Safe) for use as a spice, seasoning, or natural flavor ingredients while their essential oils, oleoresins (solvent-free), and natural extractives (including distillates) are GRAS flavoring agents.²³ For use of the essential oil as a flavoring agent, a quality standards monograph for “Ceylon Type Cinnamon Bark Oil” is published by the United States Pharmacopeial Convention in the Food Chemicals Codex.²⁴ For therapeutic use, although initially evaluated as potential active ingredients for inclusion in FDA’s establishment of a monograph for over-the-counter digestive aid drug products in 1982,25 both cinnamon oil and cinnamon tincture eventually became classified as non-monograph (Not Generally Recognized as Safe and Effective, or GRASE) in 1993.²⁶

MODERN RESEARCH

The common name cinnamon is used to refer to a number of species in the genus Cinnamomum. For clarity, Abascal and Yarnell (2010) have suggested that correct labeling of cinnamon species and products made from them should be required in any study and in any commercial product.²⁷ This should include a voucher specimen in addition to correct Latin binomial. They suggest that “very little of what passes for cinnamon in the marketplace, traditional medicine, or in modern studies is actually this true cinnamon.” Indeed, in the writing of this article, 1 author came across a systematic review that included a study on a product (Cinnulin PF^®, Integrity Nutraceuticals Intl, Spring Hill, TN, U.S. patent #6,200,569) referred to as being “made from C. burmannii of the verum genus” [sic].²⁸ Upon further investigation, this author learned that the primary article identified the species as C. cassia.²⁹ An Internet search found the product, Cinnulin PF, referred to as made from C. burmannii [sic], C. cassia, C. cassia, and C. zeylanicum, or just cinnamon bark. The manufacturer states that Cinnulin PF is a proprietary water soluble extract of C. burmannii [sic].³⁰

Chemotaxonomical studies have been conducted on C. verum and related taxa showing much variation in species as regards flavonoids, terpenoids, and steroids.² However, C. verum accessions (distinct varieties) from Sri Lanka and India were found to be chemically identical.

Cinnamomum verum has displayed antibacterial activity in vitro against methicillin-resistant Staphylococcus aureus (MRSA)³¹ and Moraxella cattarhalis.³² It has also been shown to be anti-inflammatory in vitro.³³ A number of in vitro studies have demonstrated the antioxidant potential of cinnamon but no human clinical studies are available to support cinnamon’s antioxidant properties.³⁴

Pharmacological, animal, and, to a lesser extent, clinical research suggests that certain species of Cinnamomum may have potential for the treatment of diabetes, specifically in improving metabolic measures. Cinnamomum aromaticum (syn. C. cassia) is believed to have a better glucose-lowering effect than other species.³⁵ A recent systematic review and meta-analysis of the effects of cinnamon on type 2 diabetes revealed 6 randomized, controlled trials, all on preparations made from bark of C. cassia.³⁶

Another recent systematic review and meta-analysis explored the safety and efficacy of C. verum (as C. zeylanicum) on diabetes and resulted in 16 in vivo and in vitro studies, but no human clinical trials.37 The authors concluded that C. verum displays numerous beneficial effects (and no toxicity in vivo and in vitro), including promoting glycemic control, healthy lipid parameters, reduction of insulin resistance, potentiation of the action of insulin, and amelioration of common complications associated with diabetes. While C. verum may have potential for treating some symptoms associated with type 2 diabetes mellitus, clinical trials, like those being conducted on C. cassia, are required to confirm safety and efficacy in humans.

FUTURE OUTLOOK

A number of studies have concentrated on choosing cinnamon genotypes for crop improvement. Joy et al. (1998) investigated the genetic variability of cinnamon accessions from the Aromatic and Medicinal Plants Research Station at Kerala Agricultural University (KAU) in Odakkali, Kerala, India, and identified superior genotypes recognizable by the color of the flushes.² The accessions with the darker purple flush yielded 29% more bark oil. Additionally, accession collections at the Indian Institute of Spices Research (IISR) and KAU, and collections derived from these 2 sources, have been used to develop better lines of cinnamon based on analysis of their genetic variability (fresh and dry bark yield, leaf oil, percentage of eugenol in leaf oil and cinnamaldehyde in bark oil, regenerative capacity, etc.) and were released for cultivation in India in the latter part of the 1990s.²

In Sri Lankan commercial plantations, cinnamon is usually maintained as a bush with 4-5 slender shoots growing to 6-10 feet (2-3 m).³⁸ The bark can be harvested 2-3 years after planting, 2-3 times per year depending on growing conditions, and each plant has a commercially viable lifespan of 30-40 years. Cinnamon has a few insect pests and diseases that can affect crop production but there is very little information on their management.³⁹

For the analysis of import and export trade data the World Customs Organization (WCO) assigns a general 4-digit harmonized system code that is inclusive of all cassia and cinnamon barks as well as cinnamon tree flowers of all Cinnamomum species (HS 0906). Related 6-digit codes are also assigned which can provide somewhat more specificity. Trade of Ceylon type cinnamon (C. verum) bark and tree flowers is tracked under HS 090611. Individual producing and exporting countries may add additional unique digits to create country-specific 8-, 9-,10- or 12- digit codes which enable quantification of export trade value for different plant parts and processed forms. According to the United Nations COMTRADE database, the world total export trade value for HS 0906 in 2010 was USD $248,558,721. Over 83% of the total was accounted for by just 4 countries. Sri Lanka ranked at #1 with a $82,794,825 export value (mainly C. verum); Indonesia #2 with $48,413,718 (C. burmanii, but also C. aromaticum and C. verum); People’s Republic of China #3 with $46,785,242 (mainly C. aromaticum); and Vietnam at #4 with $29,307,553 (mainly C. loureirii, but also C. aromaticum). If the major non-producing but re-exporting countries (e.g., Germany, France, The Netherlands, and United States) are taken out of the equation, the top-4 exporters account for about 90% of the world total. India and Madagascar (C. verum), respectively, each accounted for less than 1% of total export value in 2010.⁴⁰

—Gayle Engels and Josef Brinckmann

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