Turmeric has been shown in vitro to inhibit platelet-activating factor and platelet aggregation. Therefore, turmeric may potentiate the effects of anticoagulants, platelet inhibitors, and thrombolytic agents, and could increase risk of bleeding. Caution should be used when taking warfarin, clopidogrel bisulfate, aspirin, and similar drugs along with turmeric.1
An active constituent of turmeric, curcumin, may potentiate the effects of chemotherapeutic drugs such as paclitaxel. Caution should be taken when considering the addition of turmeric or curcumin to cancer therapeutic drugs.2
Turmeric may interfere with drugs that reduce production of stomach acid such as cimetidine, famotidine, ranitinide, esomeprazole, omeprazole, and lansoprazole.3
Since turmeric may alter insulin production or glucose metabolism, turmeric may interfere with drugs that lower blood sugar. 3
Turmeric is a shrub related to ginger and is native to tropical regions of southern Asia. The root is used as a spice, a coloring agent, and in traditional medicine.
Turmeric has been used to aid digestion and liver function, relieve arthritis pain, and regulate menstruation in Chinese and Ayurvedic medicine.
Curcumin is thought to be the active compound in turmeric, and is approximately 2-8% of the dried root.4 Curcumin is a non-water soluble polyphenolic compound and imparts the yellow color to turmeric. Curcuminoid compounds found in turmeric include curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Turmeric also contains several volatile oils including tumerone, atlantone, and zingiberone.
In vitro and animal studies suggest that turmeric has antioxidant5, anti-inflammatory5,6,7, and anticancer6,7 properties. Clinical trials are currently in progress to investigate these possible activities.5
Curcumin may regulate transcription factors (nuclear factor-kB), growth factors (vascular endothelial cell growth factor), inflammatory cytokines (tumor necrosis factor, interleukin 1 and interleukin 6), protein kinases (mammalian target of rapamycin, mitogen-activated protein kinases, and Akt) and other enzymes (cyclooxygenase 2 and 5 lipoxygenase). 5,6,7
Effects of Curcuma longa (turmeric) on postprandial plasma glucose and insulin in healthy subjects.
A small crossover design trial investigated the effects of turmeric on plasma glucose and insulin after an oral glucose tolerance test. Fourteen healthy people without diabetes or metabolic syndrome participated in the trial. Participants each consumed either 6 g turmeric with 170 mg lactose or 560 mg lactose prior to the oral glucose tolerance test. The glucose tolerance test was accomplished with a standard 75 g glucose beverage; finger-prick capillary and venous blood samples were collected at baseline, 15, 30, 45, 60, 90, and 120 min. For the turmeric supplement, the glucose beverage also contained 390 mg lactose to provide the same amount of lactose in both placebo and turmeric trials. Turmeric supplements increased serum insulin at 30 and 60 minutes after the oral glucose tolerance test (P=0.048 and 0.033). The change in insulin level was significantly different from the change in insulin level after the reference meal 30 and 60 min (P=0.03 and P=0.041, repectively). Consumption of the turmeric supplements also produced a significantly higher postprandial serum insulin area under the curve (AUC) at 15, 30, 90, and 120 min after the oral glucose tolerance test (P=0.048, P=0.035, P=0.03, P=0.02, respectively). This preliminary trial suggests that turmeric supplements may increase insulin response but did not alter glucose levels in healthy people. Further trials should be conducted to assess the interaction between turmeric, insulin secretion, and blood glucose.4
Efficacy and safety of Curcuma domestica extracts in patients with knee osteoarthritis.
A six-week randomized clinical trial investigated the efficacy of Curcuma domestica extracts, a variety of turmeric, on symptoms of knee osteoarthritis. One-hundred-seven people with osteoarthritis of the knee participated in the study. Participants had pain scores greater than or equal to 5 at the beginning of the trial. Study participants were randomly assigned to receive 800 mg ibuprofen (55 people) or 2 g C. domestica extracts (52 people) daily. The outcomes were improvement in pain on level walking, pain on stairs, and functions of knee assessed by time spent during 100-m walk, and going up and down a flight of stairs; outcomes were significantly improved at weeks 0, 2, 4, and 6 compared with the baseline values for both groups. There was no difference between the groups, except for pain on stairs (p=0.016). This study suggests that C. domestica extracts are as effective as ibuprofen for osteoarthritis of the knee. Further trials are necessary to evaluate these results.8
Turmeric extract may improve irritable bowel syndrome symptomology in otherwise healthy adults: a pilot study.
A partially-blinded, randomized, two-dose pilot study investigated the use of turmeric tablets for irritable bowel syndrome (IBS) symptoms. The study was only partially-blinded: participants knew there were two supplemented groups but did not know their group assignments. Two-hundred-seven people with IBS participated in the eight week trial. Participants consumed either one or two tablets daily containing 72 mg curcumin/tablet (i.e. one group consumed 72 mg curcumin daily while the other consumed 144 mg curcumin daily); the tablets are a commercially available proprietary product. Symptoms were assessed by questionnaire. Both one and two tablets daily significantly decreased IBS prevalence (41% and 57%) between initial screening and the baseline measurements. Between baseline and the end of treatment (eight weeks), a significant decrease was found for each group: one tablet (53%) and two tablet (60%) (p<0.001). The abdominal pain/discomfort score was significantly reduced in each group: one tablet (22%) and two tablet (25%) (tending to significance p=0.071). Approximately two thirds of all subjects reported improvement in symptoms: one tablet (67%) and two tablet (70%). The results of this pilot study suggest that turmeric supplements may help people with IBS. Since these results are preliminary and some studies have not found the same benefits, further trials are essential to evaluate the efficacy of turmeric for IBS.9
Content of redox-active compounds (ie, antioxidants) in food consumed in the United States.
This extensive in vitro study investigated the amounts of antioxidants and differences in activity of antioxidants from various foods. The antioxidant assay used determined the mmol electrons per donated hydrogen per 100 g. (Some studies use Trolox equivalents; to convert between the two measurements, the activity of the synthetic antioxidant Trolox is 831.00 mmol electrons/donated H/100 g.) Turmeric powder was found to have 15.679 mmol/100 g. A serving of turmeric is 1 teaspoon (2.2 g) which provides 0.345 mmol antioxidant activity. Turmeric was in the top ten antioxidant containing foods studied. This in vitro study suggests that turmeric provides a significant quantity of antioxidants in the diet. This antioxidant capacity may contribute to the functions of turmeric.10
Lipophilic and hydrophilic antioxidant capacities of common foods in the United States.
The antioxidant capacities of common foods were determined. Lipophilic and hydrophilic antioxidant capacities were determined independently relative to Trolox (Trolox equivalents; TE), a synthetic antioxidant. Total antioxidant capacity was determined from the sum of the lipophilic and hydrophilic antioxidant capacities. For turmeric, the lipophilic antioxidant capacity was determined to be 1193.46 micromol TE/g while the hydrophilic antioxidant capacity was found to be 399.31 micromol TE/g (total antioxidant capacity 1592.77 micromol TE/g). Since daily total hydrophilic and lipophilic antioxidant capacity intakes were calculated to be 5558 and 166 micromol TE, turmeric is a significant source of antioxidant capacity.11
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