Other common name(s): jiang huang, haridra, Indian saffron
Scientific/medical name(s): Curcuma longa, Curcuma domestica
Turmeric is a spice grown in India and other tropical regions of Asia. It has a long history of use in herbal remedies, particularly in China, India, and Indonesia. The root and rootstock, or rhizome, of the plant contain curcumin, which is considered to be the active ingredient. Curcumin is not related to cumin, which is a spice made from the seeds of a different plant.
Turmeric is a common food flavoring and coloring in Asian cooking. Animal and laboratory studies have found that curcumin, an antioxidant that is an active ingredient in turmeric, demonstrated some anti-cancer effects in the lab. But human research is needed to determine curcumin's role in cancer prevention and treatment in people. Several types of cancer cells are inhibited by curcumin in the laboratory, and curcumin slows the growth and spread of some cancers in some animal studies. Clinical trials are underway to find out if it can help humans as well.
Curcumin is being studied to find out whether it helps other diseases such as arthritis, Alzheimer’s disease, and stomach ulcers. It is also being studied to see whether it can help lower “bad cholesterol” and improve outcome in kidney transplants. A few early studies have been done in humans, but much more human research is still needed to find out if curcumin can be effective in these uses.
How is it promoted for use?
Some proponents believe turmeric may prevent and slow the growth of a number of types of cancer, particularly tumors of the esophagus, mouth, intestines, stomach, breast, and skin.
Turmeric is promoted mainly as an anti-inflammatory herbal remedy and is said to produce fewer side effects than commonly used pain relievers. Some practitioners prescribe turmeric to relieve inflammation caused by arthritis, muscle sprains, swelling, and pain caused by injuries or surgical incisions. It is also promoted as a treatment for rheumatism and as an antiseptic for cleaning wounds. Some proponents claim turmeric interferes with the actions of some viruses, including hepatitis and HIV.
Supporters also claim that turmeric protects against liver diseases, stimulates the gallbladder and circulatory systems, reduces cholesterol levels, dissolves blood clots, helps stop external and internal bleeding, and relieves painful menstruation and angina (chest pains that often occur with heart disease). It is also used as a remedy for digestive problems such as irritable bowel syndrome, colitis, Crohn’s disease, and illnesses caused by toxins from parasites and bacteria.
Because lab studies suggest that curcumin can help slow the growth of cancer cells, some people say that it can do the same in humans.
What does it involve?
Turmeric root is on the Commission E (Germany’s regulatory agency for herbs) list of approved herbs, used for dyspepsia (upset stomach) and loss of appetite. It is available in powdered form as a spice in most grocery stores. It can also be made into a tea or purchased as a tincture, capsule, or tablet, and is sometimes sold in combination formulas with other herbs. Ointments or pastes made from turmeric can be applied to the skin. Although there is no standardized dose for turmeric, some practitioners recommend taking a teaspoon of the powdered spice with each meal. The dried root of turmeric normally contains from 3% to 5% curcumin.
Because curcumin is thought to be the most active component of turmeric, many buyers seek out purer formulas of curcumin rather than whole turmeric. Some sellers market supplements that claim to be standardized to contain 95% curcumin compounds. Others sell mixed products that are supposed to promote the absorption of curcumin into the bloodstream.
What is the history behind it?
The use of turmeric was described in traditional Chinese and Indian medicine as early as the seventh century AD. In various Asian folk medicine traditions, turmeric has been used to treat a long list of conditions, including diarrhea, fever, bronchitis, colds, parasitic worms, leprosy, and bladder and kidney inflammations. Herbalists have applied turmeric salve to bruises, leech bites, festering eye infections, mouth inflammations, skin conditions, and infected wounds. Some people inhale smoke from burning turmeric to relieve chronic coughs. Turmeric mixed with hot water and sugar is considered by some herbalists to be a remedy for colds.
In India and Malaysia, there is a custom of making turmeric paste to apply directly onto the skin, a practice now under study for the possibility that it may prevent skin cancer. The bright red forehead mark worn by some Hindu women is sometimes created by mixing turmeric with lime juice. Chefs frequently add turmeric to their creations because of its rich flavor and deep yellow-orange color. The seasoning is an important ingredient in Indian curries. It is also used to add color to foods such as butter, margarine, cheese, and mustard; to tint cotton, silk, paper, wood, and cosmetics; as a food preservative; and to make pickles.
What is the evidence?
Curcumin, an active ingredient in turmeric, is an antioxidant. Antioxidants are compounds often found in plants that can protect the body’s cells from damage caused by activated molecules known as free radicals. Laboratory studies have also shown that curcumin interferes with several important molecular pathways involved in cancer development, growth, and spread. Researchers have reported that curcumin inhibited the formation of cancer-causing enzymes in rodents.
Recently, curcumin has received a great deal more attention in studies than turmeric as a whole herb. Researchers are studying curcumin to learn whether it is an effective anti-inflammatory agent and whether it holds any promise for cancer prevention or treatment. A number of studies of curcumin have shown promising results. Curcumin can kill cancer cells in laboratory dishes and also slows the growth of the surviving cells. Curcumin has been found to reduce development of several forms of cancer in lab animals and to shrink animal tumors.
Human studies of curcumin in cancer prevention and treatment are in the very early stages. In scientific studies, curcumin does not absorb well from the intestine, so that big doses must be taken for even small amounts to get into the blood circulation. Large doses of curcumin would need to be taken in order to study any effects it might have in the body.
One study of 15 patients with colorectal cancer was done to find out how much curcumin they could safely take, and whether they could take a dose large enough to even be detected in the blood. The patients were able to take 3.6 grams of curcumin without noting ill effects. At this high dose, some curcumin and its products were found in the blood. Lower doses may be enough to directly affect the stomach and intestine. Even though it does not absorb well into the bloodstream, curcumin absorbs into the colon lining and into cancerous tissues in the colon. Small studies have found most people in study groups were able to take up to 10 grams of curcumin per day for a period of a few weeks without noticing problems other than the large volume of pills. There are also studies going on now that try different ways to formulate curcumin so that it absorbs well enough to be tested in humans.
A 2011 study took advantage of the fact that curcumin stays in the intestine rather than absorbing into the blood. Researchers tested it to find out if it could reduce the number of cancer precursors in the colon and rectum. They measured compounds that help promote cancer in rats, did colonoscopies to count abnormal crypt foci (a very early sign that colon cancer may be developing) in biopsy samples, then gave 2 to 4 grams of curcumin a day to 44 smokers. After a month on the curcumin, the researchers did second colonoscopies and biopsies to see if there was a lower concentration of pro-carcinogenic substances in the colon and rectum. The compounds were at the same level as they were before the study. But the smokers who took 4 grams of curcumin a day had fewer abnormal crypt foci after the study, while the smokers who took 2 grams a day had the same number as before. Researchers are still looking at whether curcumin might actually reduce the number of colon and rectum cancers.
Further clinical trials are going on to find out what role, if any, turmeric and curcumin may play in the prevention or treatment of cancer.
Curcumin is being studied to see whether it helps other diseases as well. One small study of curcumin and another antioxidant called quercetin was done in adults who had kidney transplants. Those who took the combination in high dosages had fewer transplant rejections than those who received lower doses or placebo. More studies are needed to find out whether this holds true. Curcumin may also promote the emptying of the gallbladder, but again, more studies are needed.
Early research has suggested that curcumin may help lower "bad" cholesterol, reduce inflammation, help ulcerative colitis, and reduce arthritis symptoms, although more reliable human studies are still needed. Tests of curcumin in HIV disease have been mixed and have generally not shown it to be helpful. In studies of mice, curcumin appeared to help block the plaques and proteins that cause problems in the brain during Alzheimer’s disease. Human studies have already started to look at this.
Although laboratory and animal tests look very promising, careful study is needed to find out whether curcumin will be useful for treating these conditions in humans. It is important to remember that extracted compounds such as curcumin are not the same as the whole herb. Studies that look at a whole herb often show different effects, and the quantity of whole herb needed to produce a certain effect in the body would be greater than for an extract.
Are there any possible problems or complications?
This product is sold as a dietary supplement in the United States. Unlike companies that produce drugs (which must be tested before being sold), the companies that make supplements are not required to prove to the Food and Drug Administration that their supplements are safe or effective, as long as they don't claim the supplements can prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or substance that is on the label, and some may include other substances (contaminants). Actual amounts per dose may vary between brands or even between different batches of the same brand. In 2007, the FDA wrote new rules to improve the quality of manufacturing for dietary supplements and the proper listing of supplement ingredients. But these rules do not address the safety of the ingredients or their effects on health.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.
When used as a spice in foods, turmeric is considered safe. More research is needed to establish the safety of turmeric when used in herbal remedies. Little is known about the potential risks of taking the larger amounts used to treat illnesses. Taking large amounts by mouth may result in stomach pain, gas, indigestion, and nausea. Skin rash and stomach ulcers have been reported after long-term use, and allergic reactions are possible. People who are allergic to ginger or yellow food colorings are more likely to be allergic to turmeric. There have also been reports of rashes (contact dermatitis) after touching curcumin.
A recent safety study in humans suggested that curcumin changes metabolism of oxalate, a substance that can form kidney stones. The researchers urged caution in use of this supplement by people with other conditions that make them susceptible to kidney stones..
People taking blood-thinning medications, drugs that suppress the immune system, or non-steroidal pain relievers (such as ibuprofen) should avoid turmeric because of the risk of harmful drug interactions. In animal and laboratory studies, turmeric made certain anti-cancer drugs less effective. Antioxidant supplements can interfere with the effectiveness of chemotherapy or radiation treatment. Patients who are in cancer treatment should talk to their doctor before taking vitamins, minerals, or other supplements.
In addition, other potential interactions between turmeric and other drugs and herbs should be considered. Always tell your doctor and pharmacist about any herbs or supplements you are taking.
People with bile duct blockage or gallstones and those who have had stomach ulcers also should avoid turmeric. Women who are pregnant or breast-feeding should not use this herb. The amount of turmeric found in foods is thought to be safe for those who are not allergic to it. Applying turmeric to the skin for long periods of time can cause a yellow stain that may be difficult to remove.
Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.
To learn more
More information from your American Cancer Society
Here is more information you might find helpful. You also can order free copies of our documents from our toll-free number, 1-800-227-2345, or read them on our Web site, www.cancer.org.
The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management
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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.
Last Revised: 12/07/2012