Leaves from a wild cinnamon tree Cinnamon is a spice obtained from the inner bark of several trees from the genus Cinnamomum that is used in both sweet and savoury foods. While Cinnamomum verum is sometimes considered to be "true cinnamon", most cinnamon in international commerce is derived from related species, which are also referred to as "cassia" to distinguish them from "true cinnamon". Cinnamon is the name for perhaps a dozen species of trees and the commercial spice products that some of them produce. All are members of the genus Cinnamomum in the family Lauraceae. Only a few of them are grown commercially for spice. History Cinnamomum verum, from Koehler's Medicinal-Plants (1887) In classical times, four types of cinnamon were distinguished (and often confused): Cassia, the bark of Cinnamomum iners from Arabia and Ethiopia, literally 'the peel of the plant' which is scraped off the tree. True cinnamon, the bark of C. verum (also called C. zeylanicum) from Sri Lanka Malabathrum or malobathrum, several species including C. tamala from the north of India Serichatum, C. cassia from Seres, that is, China. Cinnamon has been known from remote antiquity. It was imported to Egypt as early as 2000 BC, but those who report that it had come from China confuse it with cassia. Flavour, aroma and taste The flavour of cinnamon is due to an aromatic essential oil that makes up 0.5% to 1% of its composition. This essential oil is prepared by roughly pounding the bark, macerating it in sea water, and then quickly distilling the whole. It is of a golden-yellow colour, with the characteristic odour of cinnamon and a very hot aromatic taste. The pungent taste and scent come from cinnamic aldehyde or cinnamaldehyde (about 90% of the essential oil from the bark) and, by reaction with oxygen as it ages, it darkens in colour and forms resinous compounds. Other chemical components of the essential oil include ethyl cinnamate, eugenol (found mostly in the leaves), beta-caryophyllene, linalool, and methyl chavicol. Uses Cinnamon bark Besides use as flavourant and spice in foods, cinnamon-flavoured tea, also flavoured with cardamom, is consumed as a hot beverage in Bangladesh, India and Pakistan. Cinnamon bark is widely used as a spice. It is principally employed in cookery as a condiment and flavouring material. It is used in the preparation of chocolate, especially in Mexico, which is the main importer of cinnamon. It is also used in many dessert recipes, such as apple pie, doughnuts, and cinnamon buns as well as spicy candies, coffee, tea, hot cocoa, and liqueurs. True cinnamon, rather than cassia, is more suitable for use in sweet dishes. In the Middle East, cinnamon is often used in savoury dishes of chicken and lamb. In the United States, cinnamon and sugar are often used to flavour cereals, bread-based dishes, such as toast, and fruits, especially apples; a cinnamon-sugar mixture is even sold separately for such purposes. It is also used in Turkish cuisine for both sweet and savoury dishes. Cinnamon can also be used in pickling. Cinnamon bark is one of the few spices that can be consumed directly. Cinnamon powder has long been an important spice in Persian cuisine, used in a variety of thick soups, drinks, and sweets. It is often mixed with rosewater or other spices to make a cinnamon-based curry powder for stews or just sprinkled on sweet treats (most notably Shole-zard, Persian شله زرد). It is also used in sambar powder or BisiBelebath powder in Karnataka, which gives it a rich aroma and unique taste. Cinnamon has been proposed for use as an insect repellent, although it remains untested. Cinnamon leaf oil has been found to be very effective in killing mosquito larvae. Of the compounds found in the essential oil from cinnamon leaves, cinnamyl acetate, eugenol, and anethole, and in particular cinnamaldehyde, were found to have the highest effectiveness against mosquito larvae. Cinnamon, as a warm and dry substance, was believed by doctors in ancient times to cure snakebites, freckles, the common cold, and kidney troubles, among other ailments. However, newer studies showed that some substances in cinnamon, particularly coumarin, may cause liver damage in some sensitive people. Cinnamon along with garlic is used as a fish and meat preservative and in the future might be used in an inner layer of plastic as it has antimicrobial properties up to 120 degree Celsius; they can also be used to preserve fried and deep fried foods. Beneficial effects Cinnamon is used in traditional medicine, and several studies have tested chemicals extracted from cinnamon for various possible medicinal effects. Anti-viral In an experiment testing the effects of various plants used in traditional Indian medicine, an extract of Cinnamomum cassia had an effect on HIV-1. Another study found that eugenol, a chemical found in cinnamon essential oils, and in other plants, inhibited the replication of the virus causing herpes in vitro.The compound cinnzeylanine, from C. zeylanicum, also had antiviral properties in a model system using silkworm cells. Diabetes Two studies have shown that including cinnamon and cinnamon extract in the diet may help type 2 diabetics to control blood glucose levels. One study used C. cassia, while the other study used an extract (made from "Chinese Cinnamomum aromaticum", an older name for C. cassia). Apart from the most common flavanol (epi)catechin and (epi)afzelechin, cinnamon proanthocyanidins contain (epi)catechingallate and (epi)gallocatechin units. Furthermore, these proanthocyanidins are bioavailable and may have an effect on the target tissues. However a Cochrane review study published in 2012 found that cinnamon was not more effective than placebo in reducing glucose levels and glycosylated haemoglobin A1c (HbA1c) (a long-term measurement of glucose control in diabetes). Authors concluded that "There is insufficient evidence to support the use of cinnamon for type 1 or type 2 diabetes mellitus". Antioxidant Pharmacological experiments suggest that dietary cinnamon-derived cinnamic aldehyde (cinnamaldehyde) activates the Nrf2-dependent antioxidant response in human epithelial colon cells and may therefore represent an experimental chemopreventive dietary factor targeting colorectal carcinogenesis. Recent research documents antimelanoma activity of cinnamic aldehyde observed in cell culture and a mouse model of human melanoma. Alzheimer's disease A 2011 study isolated a substance (CEppt) in the cinnamon plant that inhibits development of Alzheimer's disease in mice. CEppt, an extract of cinnamon bark, seems to treat a mouse model of Alzheimer's disease. Adverse effects The European Food Safety Authority in 2008 considered toxicity of coumarin, known to cause liver and kidney damage in high concentrations and a significant component of cinnamon, and metabolic effect on humans with CYP2A6 polymorphism, and confirmed a maximum recommended Tolerable Daily Intake (TDI) of 0.1 mg of coumarin per kg of body weight. 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. These limits are low enough to affect the flavour of cinnamon pastries. Complexion problems Over the ages, cinnamon has been used in unconventional medicine as a good way to treat skin problems. Cinnamon enjoys the largest popularity in Asia – especially in India and China. The minerals contained in this old spice sooth the skin and help to eliminate acne and pimples. Therefore, cinnamon is used as an ingredient in plenty of traditional beauty masks.