Turmeric

• 1. Introduction

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  Turmeric, known to botanists as Curcuma longa, may owe its English name to the Latin phrase terra merita, which means deserved earth. The Latin word longa in its scientific name simply means long. That modest label sits oddly on a root that has stained robes, painted bodies, flavored curries and ended up in chemistry classrooms. Few plants cross so many worlds at once. This documentary follows turmeric through all of them. Where did the plant come from, and why is its identity still disputed? Who first carried it across open ocean, and for what purpose? Why does a golden powder appear at weddings, in kitchens, in laboratories and in food-safety alerts? And what does careful science say about its reputation as a cure?

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• 2. A Rhizome of Uncertain Identity

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  Temperatures between 20 and 30 degrees Celsius, along with heavy yearly rainfall, are what turmeric needs to thrive. It is a perennial herb in the ginger family, Zingiberaceae, and it is native to the Indian subcontinent and Southeast Asia. Farmers dig up the plants every year. Some rhizomes are saved to be planted the following season, while others go to the kitchen or the dye pot.

  A mature plant stands up to about 1 meter tall. Its rhizomes are highly branched, cylindrical, aromatic, and yellow to orange. The leaves grow in two rows, and their sheaths together form a false stem. Each leaf stalk runs 50 to 115 centimeters, and the blades are usually 76 to 115 centimeters long, though they can reach 230. The blades are 38 to 45 centimeters wide.

  In East Asia, turmeric usually flowers in August. The flower spike is 12 to 20 centimeters long, and the bracts at its tip carry no flowers at all. They range from white to green, and some are tinged reddish-purple. Each flower has three bright-yellow petals fused into a tube up to 3 centimeters long. Only one stamen is fertile, and the rest have turned into sterile structures called staminodes. The fruit is a capsule that splits open into three compartments.

  The genus Curcuma is far larger than the single plant on the spice shelf. India holds the greatest number of species, around 40 to 45, and Thailand has a comparable 30 to 40. Other tropical Asian countries also have many wild species. Several lookalike plants carry overlapping local names, and some of them are sold as turmeric in other parts of Asia.

  Only the specimens from South India can be firmly identified as Curcuma longa, which leaves the plant's wider family tree unsettled.

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• 3. Dye Before Spice

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  Around 3000 BCE, Austronesian peoples began to disperse from Taiwan, and language evidence suggests they already knew turmeric soon afterward, before any contact with India. In Indonesia and the Philippines it served as food, textile dye, medicine and body paint. It was also a regular ingredient in animistic rituals. The linguists Kikusawa and Reid concluded in 2007 that kunij, the oldest reconstructed Proto-Malayo-Polynesian word for turmeric, reflects its value as a dye. Related Curcuma plants from Southeast Asia, such as Curcuma zedoaria, were eaten and used as spice but not as dye.

  The Lapita people carried both turmeric and Curcuma zedoaria into Oceania. Turmeric grows only from rhizomes, so its presence on Pacific islands before European arrival means someone planted it there on purpose. People in Micronesia, Island Melanesia and Polynesia, reaching as far as Hawaii and Easter Island, used it widely for food and dye. On some smaller islands with sandy soil, the rhizomes stayed too small, so the dye was pressed from the leaves. The atolls of the Carolines could not grow it at all. Turmeric became a trade good in the sawei exchange network, which linked those atolls with Yap. Austronesian voyagers also took it to Madagascar.

  In India, turmeric traveled alongside Hinduism and Buddhism, because the yellow dye was used to color the robes of monks and priests.

  Traces of it also turn up far from the tropics. Turmeric was found at Farmana, dated between 2600 and 2200 BCE, and in a merchant's tomb at Megiddo in Israel from the second millennium BCE. Cuneiform medical texts from Ashurbanipal's library at Nineveh, written in the 7th century BCE, list it as a dye plant. In Medieval Europe it went by the name Indian saffron, a label that hints at its later role in the kitchen.

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• 4. The Golden Kitchen

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  Boiling and drying the rhizomes, then grinding them, gives the deep orange-yellow powder found in spice racks around the world. The flavor is warm and bitter, rather like black pepper, and the aroma is earthy and close to mustard. Cooks also use the rhizome fresh, much as they would use ginger.

  By weight, turmeric powder is about 67 percent carbohydrate, 12 percent water, 9 percent protein and 3 percent fat. Dietary minerals make up 3-7 percent, essential oils another 3-7 percent, and fiber 22 percent. Curcuminoids account for 1-6 percent and supply the golden color. Curcumin is the best known of them, alongside demethoxycurcumin and bisdemethoxycurcumin. Assayed commercial turmeric powder averages 3.14 percent curcumin by weight, while curry powder averages only 0.29 percent. Some 34 essential oils are present, and turmerone, germacrone, atlantone and zingiberene are the major ones.

  Regional cooking shows how far the spice has traveled. Iranian khoresh stews often begin with onions caramelized in oil and turmeric. Moroccan ras el hanout typically includes it. South Africans tint boiled white rice with it to make geelrys, or yellow rice, which is traditionally served with bobotie. In Vietnam it colors bánh xèo, bánh khọt and mì Quảng. Cambodian kroeung paste, the base of fish amok, usually contains fresh turmeric. Indonesian Minang curries from Sumatra, including rendang and sate padang, rely on the leaves. In the Philippines it flavors kuning, satti and some versions of adobo. Southern Thai cooks use the fresh rhizome in yellow curry and turmeric soup.

  Sweet dishes use it too. The Lebanese cake sfouf contains turmeric, and in India the leaf wraps patoleo, a steamed parcel of rice flour and coconut-jaggery mixture cooked in a special vessel called a chondrõ. The traditional drink haldī dūdh combines turmeric with heated milk, black pepper and ghee, and some cafes now serve it as a golden latte.

  Food manufacturers value the color above all. Turmeric tints canned beverages, baked goods, dairy products, ice cream, yogurt, yellow cakes, orange juice, biscuits, popcorn, cereals and sauces. In the European Union it is a permitted food color with the code E100. Producers add it to prepared mustards and canned chicken broths, often as a cheaper stand-in for saffron, and they use turmeric oleoresin for products containing oil.

  Curcumin itself is approved as a food additive by the World Health Organization, the European Union and the United States Food and Drug Administration.

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• 5. Rituals and Cloth

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  In Bengal, the wedding ceremony gaye holud takes its name from a phrase meaning yellow on the body. Across many Hindu communities, a similar haldi ceremony has the bride and groom smeared with turmeric paste in the days before the wedding.

  In Tamil Nadu and Andhra Pradesh, the Tamil-Telugu marriage ritual uses a dried turmeric tuber tied with a string to make the Thali necklace. Along the western and coastal parts of India, Marathi and Konkani couples and Kannada Brahmins tie turmeric tubers to their wrists with strings in a ceremony called Kankana Bandhana.

  In Eastern India, turmeric is one of the nine components of nabapatrika. The others are a young plantain or banana plant, taro leaves, barley called jayanti, wood apple called bilva, pomegranate called darimba, Saraca indica, manaka or manakochu, and rice paddy.

  As a fabric dye, turmeric performs poorly because it fades in light. Even so, it is still common in Indian clothing such as saris. Japan's late Edo period, from 1603 to 1867, found another use for it. Dyers there diluted or replaced costly safflower dye with turmeric when producing a patterned cloth called beni itajime shibori. The ethnologist Friedrich Ratzel reported in his 1896 work The History of Mankind that Micronesians applied turmeric powder to their bodies, clothing, utensils and ceremonial objects. Native Hawaiians, who brought the plant to Hawaii, call it ōlena and make a bright yellow dye from it.

  Chemists found a different use for the color. Turmeric paper, also called curcuma paper, or curcumapapier in German literature, is made by soaking paper in a turmeric tincture and letting it dry. It serves as a pH indicator, changing between pH 7.4 and 9.2. The paper stays yellow in acidic and neutral solutions and turns brown to reddish-brown in alkaline ones.

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• 6. Colored With Lead

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  Between 2013 and 2019, the United States Food and Drug Administration issued import alerts on turmeric from India and Bangladesh. The reason was a simple one. Spices are sold by weight, which tempts sellers to mix in cheaper powders of a similar color, some of them toxic. Red lead, or lead(II,IV) oxide, is one example, and it turns turmeric orange-red instead of its natural gold-yellow. In 2014 the United States imported about 12 million pounds of turmeric, used for food coloring, traditional medicine and dietary supplements. Lead found in turmeric products led to recalls through 2016 in the United States, Canada, Japan, Korea and the United Kingdom.

  In Bangladesh, where turmeric is a daily food, researchers found lead chromate, a bright yellow compound, mixed into the spice. Contamination ran up to 500 times above the national limit. The investigators traced a chain of hands. Farmers passed low-grade roots to merchants, who sold them to polishers, and the polishers added lead chromate to brighten the yellow. Wholesalers then sent the product to market. Everyone in the chain, the researchers found, was unaware of what lead toxicity could do.

  Lead is not the only problem. Metanil yellow, also called acid yellow 36, is another common adulterant, and the British Food Standards Agency treats it as an illegal dye in food.

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• 7. Medicine and Doubt

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  Ayurveda, Siddha medicine, traditional Chinese medicine and Unani all count turmeric among their remedies. Wild turmeric grows in the forests of South and Southeast Asia, where it is gathered for classical Indian medicine. In 2019 the European Medicines Agency reached a careful conclusion. Scientific evidence of efficacy was insufficient, but on the strength of long traditional use, herbal teas and other oral forms could be used for mild digestive problems such as a feeling of fullness and flatulence.

  As of 2019, there is no scientific evidence that curcumin reduces inflammation. Clinical trials of turmeric and curcumin have mostly been of low quality and have shown no good evidence of a health benefit or an effect against disease. The evidence is weak that turmeric extracts relieve symptoms of knee osteoarthritis or ease muscle pain after exercise.

  Safety is a separate question from benefit. Turmeric and curcumin are generally safe, yet rare cases of immune-mediated acute liver injury have been linked to them, particularly in high-bioavailability forms. These cases typically resolve once a person stops taking the product, but severe outcomes can follow if use continues. The risk appears greatest in genetically susceptible individuals.

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