Curcuma is the name of a genus of flowering plants that represents approximately 80 species belonging to the Zingiberaceae family, more commonly known as the family of gingers. The natural range of these plants includes tropical Southeast Asia, India, and the East Indies, but they are also widely cultivated in other parts of the world that offer a warm, humid climate. They are grown as ornamental plants, or for the harvest of culinary spices or raw botanical material from which herbal remedies and essential oils may be produced.
One of the most notable species of curcuma in terms of commercial production is C. longa, also known as turmeric. Like many of its cousins in the Zingiberale order, turmeric features a tuberous rhizome, which is boiled, oven baked, and then ground into the familiar mustard-colored, peppery-flavored spice. This species is a staple of Middle Eastern and Asian cuisines where it is a traditional addition to curries, soups, and stews.
Curcuma caesia sports a purplish-black rhizome, earning it the common name of black tumeric, even though the species name literally translates to the word blue. This species is highly valued for its medicinal properties since at least 30 active compounds have been identified from oils extracted from its rhizome. It has been used to treat everything from leprosy to toothache to allergies to cancer. Unfortunately, over-harvesting of this species has led to its near extinction.
The properties of many species of curcuma are due to the presence of a group of polyphenols called curcuminoids, namely desmethoxycurcumin, bis-desmethoxycurcumin, and curcumin. These agents are responsible for the vibrant color of the rhizomes. As such, they are used as food additives to lend color to beverages, baked goods, orange juice, popcorn, ice cream, gelatins, and many other foods. They also protect foods from ultraviolet light. For this reason, curcuminoids, particularly curcumin, may also be found in various cosmetics and sunscreens.
Of all the species of curcuma that exhibit medical properties, tumeric is probably the best known since it is the most widely available commercial source of curcumin. The spice has long been significant in Ayurvedic medicine, but has also become increasingly popular in the West due to research findings supporting its possible anti-cancer value. Traditionally, curcumin is used to treat various skin and gastrointestinal disorders due to its antiseptic and antibacterial qualities. However, this substance has also been found to destroy esophageal cancer cells in vitro and has also shown potential in treating colon and pancreatic cancer as well. In addition, there is some evidence to suggest that curcumin may play a future role in treating Alzheimer's disease and multiple myeloma.