Medically reviewed on May 14, 2018
Scientific Name(s): Curcuma longa L. Synonymous with Curcuma domestica Val. Family: Zingiberaceae
Common Name(s): Turmeric , curcuma , Indian saffron , haldi
Turmeric is used as a spice in curry powders and mustard. It is being investigated in clinical trials for the treatment and prevention of cancers, particularly of the GI tract, and for treatment of colitis and Alzheimer and Huntington diseases.
Powdered turmeric root has traditionally been used as a stimulant and carminative at dosages of 0.5 to 3 g/day. Dosages of 3 to 6 g/day have been investigated for protective effects against ulcers. Daily oral doses of curcumin 3,600 mg have been typically used in clinical trials, but dosages of curcumin up to 8 g/day have been used. Higher doses are associated with adverse GI effects.
Contraindications have not been determined.
Documented emmenagogue and abortifacient effects.
None well documented.
Clinical trials report few adverse reactions. Rare cases of contact dermatitis and anaphylaxis have been reported. An increased risk of kidney stone formation is theoretically possible in susceptible individuals.
No reports of toxicity have been reported following ingestion of large amounts of turmeric.
A member of the ginger family, turmeric is a perennial plant that is cultivated throughout tropical Asia, India, and China. The plant grows to a height of 0.9 to 1.5 m and bears large, oblong leaves and funnel-shaped, dull yellow flowers. It is characterized by a thick rhizome, yellowish on the outside and deep orange or reddish brown internally. The lateral rhizomes contain more yellow coloring than the bulb. The dried primary bulb and secondary lateral rhizomes are collected, cleaned, boiled, and dried for use in medicinal and food preparations. 1 , 2 , 3
Turmeric has a warm, bitter taste and is used extensively as a food flavoring and colorant; it is a primary component of curry powders and some mustards. The spice has a long history of traditional use in Asian medicine to treat problems ranging from flatulence to hemorrhage. Use in the treatment of ringworm, as a poultice, an analgesic, and in the management of jaundice and hepatitis has been documented. 2 , 3
The rhizome contains up to 7% of an orange-yellow, volatile oil. Tumerone and artumerone together comprise about 60% of the oil, and zingiberene comprises about 25%. Cineole, d-phellandrene, d-sabinene, and borneol are present in low concentrations. The major yellow pigment has been identified as curcumin (diferuloylmethane), a phenolic antioxidant. Unlike most natural antioxidants that contain either beta-diketone or polyphenolic functional groups, curcumin possesses both active moieties. Its superior antioxidant activity has been attributed to this structural combination. Other curcuminoids structurally related to curcumin also are found in the extract and include demethoxy-curcumin and bis-demothoxy-curcumin. The turmeric rhizome additionally contains protein, fat, minerals, and carbohydrates. 2 , 3 , 4 , 5 , 6
Uses and Pharmacology
Most clinical trials focus on curcumin individually rather than turmeric. The use of curcumin as a pharmacological agent is limited by poor bioavailability. Curcumin is hydrophobic and cannot be given intravenously. Absorption after oral administration is low, and curcumin disappears rapidly from tissues after intraperitoneal administration. An encapsulated liposomal form has been investigated in animals to overcome this limitation. 2 , 7 , 8Cancer
Curcumin and its analogs have been reported to inhibit cancer at multiple stages of development, including initiation, promotion, and metastasis. 2 , 3 , 9 Curcumin is thought to act through a variety of mechanisms including the ability to induce apoptosis, inhibit angiogenesis, and modulate tumor suppressor genes. 2 , 3 , 9 , 10 , 11 Studies have also indicated that curcumin has a radiosensitizing effect on cancer cell cultures. 12 , 13Animal data
Studies conducted in animals largely found chemoprotective effects for curcumin. Cancer studies were conducted in mice and rats, in which oral, stomach, hepatic, colorectal, and skin cancers were induced. 2 , 3 , 9 However, not all experiments have shown positive results. A study in rats failed to demonstrate any effects in the prevention of prostate carcinoma. 14Clinical data
Based on positive results from in vitro studies on animal and human cancer cell lines and experiments in animals, phase I trials of curcumin in cancer patients have been conducted. Curcumin is being investigated by the National Cancer Institute for the prevention of colorectal cancer. 9 , 15 In smokers, turmeric 1.5 g daily for 30 days reduced the urinary excretion of mutagens compared with controls. 16
Trials have been conducted in patients with colorectal cancer refractory to standard therapy, primarily to explore tolerance and safety. 17 , 18 A limited number of patients demonstrated stable radiological conditions for up to 4 months after curcumin treatment. 17 , 18
Administration of curcumin to 12 patients with colorectal cancer showed pharmacologically active levels of the agent in the target tissue. 19 Reduction in the biological marker M1G after curcumin use was attributed to an antioxidant action of curcumin in the tumor. Clinical outcomes were not reported. Investigators concluded that oral doses required for pharmacologically active levels of curcumin to be achieved in similar patients with hepatic metastases were not feasible because of poor bioavailability. 2
A phase II trial of curcumin in patients with pancreatic cancer was conducted with oral curcumin. 7 Twenty-five patients received oral curcumin 8 g daily without treatment-related toxicity. One patient maintained this dosage for 18 months. Changes in cytokine levels (elevated at baseline) were recorded, a nonsignificant reduction in nuclear factor- K B was shown in most patients, and radiological stability was demonstrated in 2 patients. 7Cardiovascular effects
Studies in animals have demonstrated anti-platelet effects and positive effects on lipid profiles, including a decreased susceptibility of low-density lipoprotein to oxidation. 20 , 21 , 22 In experimental atherosclerosis in rabbits, animals receiving the extract had less damage from fatty streaks in the thoracic and abdominal aortas at 30 days than did controls. Markers of oxidative stress also were improved in the trial group. 5Clinical data
Clinical trials are lacking. Among healthy volunteers, curcumin 500 mg daily for 7 days decreased serum cholesterol and lipid peroxide levels and increased high-density lipoprotein. 2 No effect on lipid profile was observed in a trial evaluating the effect of turmeric 1.5 g daily on urinary excretion of mutagens. 16CNS effects
Reviews of animal experiments and in vitro studies describe 10 different neuroprotective mechanisms for curcumin, including reductions in inflammatory cytokines and markers, reduced oxidative damage, and decreased overall burdens of soluble and insoluble amyloid plaques. 2 , 23 , 24 Effects appear to be highly dose-dependent; low-dose dietary curcumin at nM levels is more effective. 23 , 25Clinical data
Clinical trials are generally lacking; however, pilot trials are being conducted among patients with Alzheimer and Huntington diseases. 23Diabetes
Animal studies in diabetic mice and rats have shown hypoglycemic effects for curcumin. 3 , 26 , 27 , 28 In healthy volunteers, oral turmeric 2.8 g daily for 4 weeks had no effect on fasting blood glucose levels. 29Clinical data
Clinical trials are lacking.Gastrointestinal
Pretreatment of rats with curcumin for 5 days before induction of colitis resulted in a reduction in colonic inflammation, histologic damage, and inflammatory markers. Curcumin recipients also demonstrated reduced weight loss compared with controls. 30 Another animal study showed that treatment of mice with curcumin reduced the appearance of diarrhea and the disruption of colonic architecture. 31Clinical data
A pilot study investigated the use of standardized turmeric root extract 1,800 or 3,600 mg/day in 207 patients with irritable bowel syndrome. Improvement in quality of life scores was reported by both groups. A trend favoring the higher dosage was observed in a post hoc analysis of abdominal pain and discomfort. 26 A similar pilot study conducted in patients with Crohn disease found favorable results. 32
A randomized, double-blind, placebo-controlled 6-month trial of curcumin in 89 patients as maintenance therapy in ulcerative colitis showed differences in relapse rate compared with placebo. The dose of curcumin used was 1 g twice daily, and was taken in combination with standard maintenance therapy of mesalamine or sulfasalazine. 33
Improvement in colitis has been attributed to the anti-inflammatory and antioxidant effects of curcumin. 26 , 30 , 31 Results from animal studies 34 and uncontrolled trials 35 , 36 suggest a role for turmeric in the treatment of duodenal or gastric ulcer.Other uses
Curcumin has been shown to interfere with the eicosanoid pathway involving cyclooxygenase and lipoxygenase enzymes, reflecting the traditional use of turmeric in Ayurvedic and Chinese medical systems for inflammation. 37 Older clinical trials have been conducted comparing curcumin with phenylbutazone. 2Hepato-protective
A protective effect against chloroquine-induced hepatotoxicity was demonstrated by curcumin in rats. 38 Curcumin given adjunctively with antituberculosis therapy was able to reduce the incidence of hepatotoxicity in patients in a clinical trial. 39Ophthalmic
Delayed onset of cataracts has been associated with the use of oral curcumin in rats. However, the effect was only observed at low dosages (0.002%), and a higher dosage of 0.01% showed no benefits. 40 In a clinical trial among patients with chronic anterior uveitis, curcumin appeared to be comparable with standard corticosteroid therapy at 375 mg 3 times a day. 2Skin conditions
In vitro studies and animal experiments suggest a role for curcumin in wound healing. An in vitro study demonstrated protective effects of curcumin against hydrogen peroxide in human keratinocytes and dermal fibroblasts. 6 Oral pretreatment with curcumin 100 mg/kg hastened wound healing in mice exposed to postoperative gamma-radiation. 41 Enhancement of collagen synthesis and markers of wound healing were demonstrated. Histological assessment of wound biopsy specimens showed improved collagen deposition as well as increased fibroblast and vascular densities.
Powdered turmeric root has traditionally been used as a stimulant and carminative at dosages of 0.5 to 3 g/day. Dosages of 3 to 6 g/day have been investigated for protective effects against ulcers. 35 , 36 Daily oral doses of curcumin 3,600 mg have been advocated for use in clinical trials, 18 but dosages of up to 8 g/day have been used in patients with advanced pancreatic cancer. 7 Higher doses are associated with adverse GI effects. 2
Potential emmenagogue and abortifacient effects have been described. 42 , 43 , 44 An extract of C. longa had a contraceptive effect in male rats. A reduction in sperm motility was observed in rats receiving turmeric 500 mg/kg/day as an aqueous or alcoholic extract. 45
Antiplatelet activity has been reported with turmeric use, possibly associated with an inhibition in the synthesis of prostaglandins and thromboxanes. Thus, additive effects with nonsteroidal anti-inflammatory agents may be of concern. 22 Bleeding might be enhanced if the spice is taken concomitantly with anticoagulant medication. However, despite widespread use of turmeric, no such reports of interactions have been reported.
Trials generally report few adverse reactions associated with turmeric or curcumin ingestion, even at the high dosages used in cancer trials. 7 , 18 GI symptoms have been reported. 2 , 4 , 17 Allergic contact dermatitis was reported in 2 patients after using curcumin-containing chlorhexidine solutions. 46 Patch tests were positive for curcumin in both cases. A case of anaphylaxis after ingesting turmeric has been documented. 47 Over a 3-day period, the patient experienced recurrent urticaria and angioedema that was unresponsive to treatment with epinephrine, antihistamines, and corticosteroids. Allergy testing for turmeric was positive.
Turmeric contains relatively high concentrations of oxalate, and increased levels of urinary oxalate excretion have been demonstrated. 29 The risk of kidney stone formation may be increased in susceptible individuals; however, reports of kidney problems are lacking.
Reports of toxicity following ingestion of large amounts of turmeric are lacking.
Evaluation in mice of acute and chronic use of C. longa ethanolic extracts 100 mg/kg/day for 90 days found no serious adverse reactions. Weight was not affected by chronic treatment; however, changes in heart and lung weights were reported, and white and red blood cell levels were reduced. 48
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