Overview
Turmeric is a widely used tropical herb in the ginger family. Its stalk is used both in food and in medicine, yielding the familiar yellow ingredient that colors and adds flavor to, or spices, curry. In the traditional Indian system of herbal medicine known as Ayurveda, turmeric is believed to strengthen the overall energy of the body and to relieve gas, dispel worms, improve digestion, regulate menstruation, dissolve gallstones, and relieve arthritis, among other uses.
Modern interest in turmeric began in 1971 when Indian researchers found evidence suggesting that turmeric may possess anti-inflammatory properties. Much of this observed activity appeared to be caused by the presence of a constituent called curcumin. Curcumin is also an antioxidant. Many of the studies mentioned here used curcumin rather than turmeric.
Uses and Applications
Turmeric’s antioxidant abilities make it a good food preservative, provided that the food is already yellow in color, and it is widely used for this purpose. Turmeric has been proposed as a treatment for dyspepsia. “Dyspepsia” is a catchall term that includes a variety of digestive problems, such as stomach discomfort, gas, bloating, belching, appetite loss, and nausea. Although many serious medical conditions can cause digestive distress, the term “dyspepsia” is most often used when no identifiable medical cause can be detected.
In Europe, dyspepsia is commonly attributed to inadequate bile flow from the gallbladder. While this has not been proven, turmeric does appear to stimulate the gallbladder. More important, one double-blind, placebo-controlled study suggests that turmeric does reduce dyspepsia symptoms. Another double-blind, placebo-controlled study suggests that, when taken with standard medications, curcumin can help maintain remission in people with ulcerative colitis.
Other proposed uses of turmeric or curcumin have little supporting evidence. Based on test-tube and animal studies, and on human trials too preliminary to provide any meaningful evidence, curcumin and turmeric are frequently described as anti-inflammatory substances and are recommended for the treatment of such conditions as osteoarthritis and menstrual pain. Some advocates state that curcumin is superior to standard medications in the ibuprofen family, because, at standard doses, it does not appear to harm the stomach. However, until turmeric is actually proven to meaningfully reduce pain and inflammation, such a comparison is premature. Also, high doses of curcumin might increase the risk of ulcers, and, contrary to some reports, turmeric does not appear to be effective for treating ulcers.
Animal and test-tube studies suggest (but do not prove) that turmeric might help prevent cancer. Weak evidence hints that curcumin might help prevent the heart and kidney injury potentially caused by the chemotherapy drug doxorubicin.
Some researchers have reported evidence that curcumin or turmeric might generally help protect the liver from damage. However, other researchers have failed to find any liver-protective effects, and there are even some indications that turmeric extracts can damage the liver when taken in high doses or for an extended period.
On the basis of even weaker evidence, curcumin or turmeric has also been recommended for preventing Alzheimer’s disease, cataracts, chronic anterior uveitis (an inflammation of the iris of the eye), fungal infections, and multiple sclerosis, and for treating high cholesterol.
One preliminary study failed to find curcumin helpful for lichen planus, a disease of the skin and mucous membranes. A six-month, double-blind, placebo-controlled study of thirty-six elderly persons failed to find that the consumption of curcumin (at a dose of up to 4 grams [g] daily) led to improvements in cholesterol profile.
Scientific Evidence
Dyspepsia. A double-blind, placebo-controlled study performed in Thailand compared the effects of 500 milligrams (mg) curcumin four times daily with placebo and with a locally popular over-the-counter treatment. A total of 116 people were enrolled in the study. After seven days, 87 percent of the curcumin group experienced full or partial symptom relief from dyspepsia, compared with 53 percent of the placebo group; this difference was statistically significant.
Ulcerative colitis
. Ulcerative colitis is a disease of the lower digestive tract marked by alternating periods of quiescence and flare-up. Curcumin has shown some promise for helping to maintain remission and prevent relapse. In a double-blind, placebo-controlled study, eighty-nine people with quiescent ulcerative colitis were given either placebo or curcumin (1 g twice daily) with standard treatment. In the six-month treatment period, the relapse rate was significantly lower in the treatment group than in the placebo group.
Dosage
For medicinal purposes, turmeric is frequently taken in a form standardized to curcumin content, at a dose that provides 400 to 600 mg of curcumin three times daily.
Safety Issues
Turmeric is on the GRAS (Generally Recognized As Safe) list of the U.S. Food and Drug Administration, and curcumin too is believed to be fairly nontoxic. Reported side effects are uncommon and are generally limited to mild stomach distress.
However, there is some evidence to suggest that turmeric extracts can be toxic to the liver when taken in high doses or for a prolonged time. For this reason, turmeric products should probably be avoided by persons with liver disease and by those who take medications that are hard on the liver.
In addition, because of curcumin’s stimulating effects on the gallbladder, persons with gallbladder disease should use curcumin only on the advice of a physician. Safety in young children, pregnant or nursing women, and those with severe kidney disease also has not been established.
Bibliography
Afaq, F., et al. “Botanical Antioxidants for Chemoprevention of Photocarcinogenesis.” Frontiers in Bioscience 7 (2002): 784-792.
Baum, L., et al. “Curcumin Effects on Blood Lipid Profile in a Six-Month Human Study.” Pharmacol Res. 2007
Cheng, A. L., et al. “Phase I Clinical Trial of Curcumin, a Chemopreventive Agent, in Patients with High-Risk or Pre-malignant Lesions.” Anticancer Research 21 (2001): 2895-2900.
Fowler, J. F., et al. “Innovations in Natural Ingredients and Their Use in Skin Care.” Journal of Drugs in Dermatology 9, suppl. 6 (2010): S72-S81.
Hanai, H., et al. “Curcumin Maintenance Therapy for Ulcerative Colitis.” Clinical Gastroenterology and Hepatology 4 (2006): 1502-1506.
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