Posted: 12/14/2013 Last Update: 2/4/2017
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What It Is:
Turmeric is a spice used commonly as a food coloring, flavoring agent, and is a key ingredient in curry powders and mustards. Turmeric is used in Ayurveda (traditional East Indian medicine) for abdominal ailments and arthritis. The dried, powdered roots (or rhizomes) of the plant, Curcuma longa, are used medicinally. Most research has focused on compounds in turmeric called curcuminoids and, more specifically, on the compound curcumin, which gives turmeric its orange-yellow color and is the predominant curcuminoid in turmeric. The other two curcuminoids in turmeric are demethoxycurcumin and bisdemethoxycurcumin.
What It Does:
Many uses of turmeric relate to the anti-oxidant or anti-inflammatory activities of curcumin. The anti-inflammatory action might involve blocking cyclooxygenase-2 (COX-2), the target of non-steroidal anti-inflammatory drugs (NSAIDs) like Celebrex (celecoxib) and Motrin (ibuprofen).
A critical analysis of research on curcumin extracts (as opposed to whole turmeric powder or extracts with a broader range of turmeric compounds) by experts in medicinal chemistry suggested that: 1) much of the activity of curcumin in laboratory experiments may be "false" and only due to its interference with tests; 2) regular curcumin lacks features common to useful medicines since it is poorly absorbed and unstable; and 3) several well-controlled clinical studies have failed to show clinical benefits with curcumin (Nelson, J Med Chem 2017). The analysis makes valid points -- studies to-date which have shown benefit have been small — but it avoids discussion of the potential for bioavailability-enhanced curcumin formulations which overcome absorption issues and are now the most commonly used types of curcumin supplements.
One well designed study found turmeric powder better than placebo for symptoms of indigestion. In this study, 116 participants took either a placebo or 500 mg of turmeric four times daily for seven days. Eighty-seven (87%) percent of the people who took turmeric reported improvement compared to 53% of the placebo group (Thamlikitkul, J Med Assoc Thai 1981).
Some small, but well-designed, studies have found curcumin helpful to people with ulcerative colitis. In one study, 50 people with active, mild to moderate ulcerative colitis not responsive to standard therapy with 5ASA were given 1.5 grams of curcumin twice a day (3 grams per day of curcumin) or placebo for one month with continued 5ASA treatment. At week four, none of the patients who received placebo achieved remission, while a startling 53.8% of those receiving curcumin did. Adverse events were rare and comparable between the two groups. The curcumin used was Cur-Cure™ (Bara Herbs, Israel), a 95% pure curcumin preparation (Lang, Clin Gatroenterol Hepatol 2015). Another well-designed study found that curcumin, in addition to conventional medications, was better than placebo for maintaining remission in people with ulcerative colitis. During the six months of this study with 89 participants, those treated with one gram of curcumin twice daily had fewer relapses than the people who took placebo (Hanai, Clin Gastroenterol Hepatol 2006). A very small pilot study also suggested a benefit with curcumin in treating ulcerative proctitis and Crohn's disease (Holt, Digestive Diseases and Sciences 2005).
The results of human studies using turmeric for treating gastric or duodenal ulcers conflict. At least two studies found no benefit while a third found that turmeric improved symptoms. Additionally, while some animal research suggests that turmeric might help prevent ulcers, other animal research suggests that turmeric might increase the risk of ulcers.
As noted in a meta-analysis of several clinical studies, there is compelling evidence that curcumin (about 1,000 mg per day) can be effective in treating symptoms (mainly pain and inflammation) of osteoarthritis and rheumatoid arthritis, although larger studies are needed to confirm these findings before a definitive recommendation can be made (Daily, J Med Food 2016). More details regarding the use of curcumin in each type of arthritis are below.
Two small studies have shown that curcumin may reduce symptoms of rheumatoid arthritis including joint
swelling and stiffness and walking time. In one study, 1,200 mg of curcumin
reduced symptoms, but not as well as the non-steroidal anti-inflammatory drug
(NSAID), phenylbutazone (Deodhar,
Indian J Med Res, 1980). In a more recent study, 500 mg twice daily of a bioavailability-enhanced curcumin product (BCM-95, Biocurcumin) was comparable to a low-dose (50 mg) of diclofenac (an NSAID) twice daily, after 8 weeks. Symptoms were reduced by about 40% from the beginning to the end of the study. Combining the curcumin and diclofenac was no more effective than either one alone (Chandran, Phytother Res 2012). A weakness of this study is that there was no placebo control group. (Note: The curcumin used in this study, BCM-95 is listed as an ingredient in the Life Extension and Progressive Laboratories products tested and discussed in this Review, below.)
A small placebo-controlled study of people with mild to moderate osteoarthritis of the knee found treatment with curcuminoids to be helpful. Six weeks of daily treatment with 1,500 mg of a curcuminoid complex resulted in significantly greater reductions in the severity of osteoarthritis symptoms than with placebo, with a particular reduction in pain and an improvement in physical function. Reports of stiffness were reduced in both the treatment and placebo groups, although not significantly more so in the treatment group (Panahi, Phytother Res 2014). Those receiving curcumin were able to reduce their use of anti-inflammatory drugs by 84% during the study -- significantly more than the 19% reduction among those in the placebo group. The curcumin used in the study was taken three times each day as a capsule containing 500 mg of cucuminoids as C3 complex® including 5 mg of Bioperine®, a bioavailability enhancer. This ingredient, C3 complex®, is found in two products listed below in this review: Doctor's Best Best Curcumin C3 Complex and Nutrigold Turmeric Cucumin Gold, although the concentration of Bioperine® is lower in these products (2.5 mg rather than 5 mg per 500 mg of C3 complex®).
There is only slight additional benefit to taking curcumin along with an anti-inflammatory drug for osteoarthritis. A study evaluated the effect of daily curcumin (500 mg of a 95% curcuminoid extract) or a placebo (talc) in patients also given the anti-inflammatory drug diclofenac (50 mg/day) and omeprazole (20 mg/day, given to reduce gastric side effects of diclofenac). Not surprisingly, at two months both groups reported major improvements in joint pain, stiffness and function, but the curcumin group showed only slightly better improvement in pain and function, e.g., the pain score fell from 15 to 9.5 in the curcumin group and from 15 to 10.2 in the placebo group. The curcumin group had greater decreases in markers of oxidative stress, but not in levels of IL-1 beta, a marker of inflammation. Neither group showed knee joint improvements on X-ray. ( Srivastava, Inflammopharmacol 2016).
Although most arthritis studies have focused on curcumin, one study suggested that other constituents in turmeric may have a role. This study used a turmeric extract (NR-INF-02 "Turmacin®," Natural Remedies, India, 500 mg twice daily) which contained turmeric polysaccharides but no curcumin. The extract was found to perform better than placebo and better than chondroitin sulfate among people with osteoarthritis (Madhu, Inflammopharm 2013).
A pilot study suggests that curcumin can reduce nasal symptoms associated with seasonal allergy (allergic rhinitis). In this study, more than 200 people in China with a history of seasonal allergy took capsules containing 500 mg of curcumin (ORGANIKA Health Products, Canada) or a placebo (colored starch) daily for two months. Over this period there were significant improvements in sneezing, runny nose, and nasal congestion among those given curcumin, with the average total symptom score falling from 8 (out of a possible 12) down to 2.8, while there were no significant changes in the placebo group. Curcumin was also found to affect levels of certain inflammatory mediators, including decreases in interleukin-4 and TNF-alpha (Wu, Ann Allergy Asthma Immunol 2016).
A small study in healthy young men given 200 mg of a bioavailability-enhanced curcumin (from 1 gram of Meriva®) at breakfast and dinner for four days experienced significantly less soreness in their front thighs 48 hours after intense treadmill exercise (on the third day of treatment) than men given placebo (Drobnic, JISSN 2014). Another small, placebo-controlled study in young healthy men found that 2,500 mg of curcumin taken twice daily (a total daily dose of 5,000 mg providing roughly an equivalent amount of curcuminoids) 2 days prior to, and 3 days after, intense leg exercise moderately reduced leg pain during subsequent exercise (24 and 48 hours later), indicating a reduction in delayed onset muscle soreness (DOMS). Effects on biochemical markers of inflammation, however, were inconclusive (Nicol, Eur J Appl Physiol 2015). Interestingly, a third study found somewhat of the opposite effect. A daily dose of 400 mg of a curcumin formula containing 80 mg curcumin plus fats to enhance absorption (Longvida® Optimized Curcumin) given to healthy young men and women for two days before and four days after leg press exercises (designed to induce muscle damage) did not reduce muscle soreness compared to placebo, but it did result in somewhat smaller increases in biological markers of inflammation. As noted by the researchers "Unfortunately, the present study does not resolve confusion regarding the ability of curcumin to reduce muscle soreness following EIMD (exercise-induced muscle damage)" (McFarlin, BBA Clinial 2016).
A preliminary study in people with chronic anterior uveitis, an autoimmune disease of the eye, suggested that curcumin may be as effective as corticosteroid treatment for this condition (Lal, Phytother Res 1999).
There are anecdotal reports of curcumin being given to treat psoriasis, an autoimmune disease. However, a clinical trial with a curcuminoid complex showed a low response rate (Kurd, J Am Acad Dermatol, 2008).
Some early research suggested that curcumin could lower cholesterol. However, a 6-month study showed no significant effect associated with curcumin supplementation at 1 gram or 4 grams per day (Baum, Pharmacol Rsrch 2007).
Curcumin has been shown to suppress proliferation of a wide variety of cancer cell types in the laboratory. In addition, a study of 64 adult smokers found that taking 4 grams of curcumin for 30 days reduced the number of aberrant crypt foci (an early change in the colon that might lead to colon cancer) by 39%. Test results indicated that this activity was achieved via absorption and circulation of curcumin through the blood stream, rather than direct effects of curcumin in the colon (Carroll, Cancer Prev Res Phila 2011). However, results of a small study of patients with pancreatic cancer given 8 grams of curcumin daily showed biological activity in only about 10% of patients (Dhillon, Clin Cancer Res 2008).
Preliminary studies have shown an effect of curcumin on improving blood sugar levels, and curcumin appeared to dramatically lower the chances of prediabetes (blood sugar levels somewhat higher than normal) advancing to actual diabetes in a study of middle-aged, slightly overweight individuals in Thailand (Chuengsamarn, Diabetes Care 2012). Over nine months, none of the 97 subjects randomized to daily treatment with curcumin (1.5 grams of curcuminoids/day in 2 divided doses) became diabetic, but 19 of 104 subjects receiving a placebo did. Curcumin appeared to boost activity of the insulin-secreting cells in the pancreas. More research is needed to confirm these results in other populations.
One small clinical study in healthy, sedentary postmenopausal women found that a daily dose of 150 mg (from six 25 mg pills) of a branded curcumin ingredient (Theracurmin, Theravalues Corporation), taken for 2 months significantly lowered systolic blood pressure, but not diastolic blood pressure, compared to placebo. (Akazawa, Nutr Res 2012). The decrease in systolic blood pressure (about 5 points) was similar to that measured in women who did not take curcumin but participated in an aerobic exercise program at least 3 days per week for the duration of the study. The study does not note whether the six pills were taken together or divided throughout the day, or if they were taken with food. Curcumin has also been found to reduce systolic blood pressure in lupus patients with kidney nephritis (inflammation) taking corticosteroid and/or anti-hypertensive medications. A dose of 500 mg of turmeric (containing 22.1 mg curcumin) taken with each meal (a total daily dose of 66.3 mg curcumin) was found to significantly reduce systolic blood pressure after 3 months compared to placebo (Khajehdehi, J Renal Nutr 2012).
A small but controlled, 8-week study among people with major depression found partial support for antidepressant and anti-anxiety effects of curcumin. Patients received either placebo or curcumin (500 mg of BCM-95) twice daily and remained on pharmaceutical antidepressants during the study. At four weeks into treatment, depressive symptoms had improved equally for both groups, but from weeks 4 to 8 curcumin was significantly more effective than placebo in improving depressive symptoms. Greater efficacy was noted among individuals with atypical depression. One of the ways curcumin may affect depression, according to the researchers, is through an immune-inflammatory pathway (Lopresti, J Affect Disorders 2014). A larger, more recent study among people with major depression (about half of whom were taking a prescription antidepressant) found that a lower dose (250 mg twice daily) of BCM-95 taken for three months significantly reduced symptoms of depression, as well as anxiety, compared to placebo, and was as effective as the higher dose of 500 mg twice daily (Lopresti, J Affect Disorders 2016). As in the previous study, curcumin's effects became significant compared to placebo after the first 4 weeks, and greater efficacy was found in those with atypical depression.
Curcumin has shown some short-term beneficial effects on cognition (thinking and memory) but has, so far, failed to show a long-term benefit on cognition in people.
A small, but well-controlled study found that daily supplementation after breakfast with 400 mg of a patented curcumin formula containing 80 mg curcumin plus fats to enhance absorption (Longvida® Optimized Curcumin) significantly improved some aspects of cognitive function and fatigue in healthy men and women ages 60 to 85 (Cox, J Psychopharm 2014). One hour after ingestion of the first dose, scores on a subtraction test improved by 16%, which was significantly more than the 2% increase with placebo; however; the effect was brief — when the subjects were retested 3 hours later no benefit was found. After 4 weeks of daily supplementation at the same dose, scores among those taking curcumin improved by 17% (vs. 3% with placebo) and fatigue was reduced by 11% (vs. 4 % with placebo). While these results are intriguing, it must be noted that no benefits were found on tests of word and picture recall. Another small, but placebo-controlled study found that taking a capsule with 1,000 mg of turmeric powder (about 1/4 teaspoon) with a nutritionally-bland breakfast resulted in improvements in short-term memory in people aged 60 years or older who were newly diagnosed with pre-diabetes. When tested six hours after taking the turmeric, scores were 2.9 (out of a possible 3.0) on a test to recall numbers in sequence, compared to 2.6 prior to turmeric. Scores did not improve among those who received placebo. Interestingly, turmeric had no effect on blood sugar or insulin levels. The study also evaluated the effects of taking 2 grams of cinnamon, which had no effect on any of the parameters measured (Lee, Asia Pac J Nutr 2014).
A long-term study in Australia among older adults (mainly in their 60s) with normal cognitive function found that taking high-dose curcumin daily had no beneficial effect on cognitive function, nor on mood or general quality of life, compared to treatment with placebo over a 12-month period. The curcumin used BCM-95 CG (Biocurcumax — 88% total curcuminoids) given as a 500 mg capsule taken 3 times a day after meals with water. A fairly high percentage (26%) of those taking curcumin withdrew from the study due to side effects — most of which were gastrointestinal in nature, compared to only 4% of those taking placebo. According to the researchers, the rate of side-effects would likely have been lower had the dose been gradually ramped-up rather given at the full amount at the beginning of the study (Rainey-Smith, Br J Nutr 2016).
Laboratory and animal studies have shown curcumin inhibits several biological and chemical processes in brain cells associated with the development of Alzheimer's disease, including inflammation, oxidative stress and the formation and accumulation of amyloid-beta proteins (which form brain plaques associated with Alzheimer's). Animal studies also suggest curcumin may work similarly to acetylcholinesterase inhibitors, a class of drugs (such as donepezil (Aricept) and galatamine (Razadyne)) that may slow the progression of Alzheimer's symptoms. In mouse models of the disease, curcumin given orally appears to reach the brain and reduce oxidative damage and memory impairment (Frautschy, Neurobiol Aging 2001). However, results have been less promising in clinical trials of curcumin in people with Alzheimer's. For example, a preliminary study found that curcumin given to Alzheimer's disease patients did not significantly improve mental functioning compared to placebo (Baum, J Clin Psychopharm 2008). Another study in people with mild to moderate Alzheimer's found that curcumin did not improve cognitive function or decrease amyloid-beta (as measured in cerebrospinal fluid) compared to placebo (Ringman, Alzheimers Res Ther 2012). Curcumin (100 mg of curcumin from turmeric powder capsules) taken daily for three months has been reported to reduce agitation, anxiety and irritability in three people with severe Alzheimer's disease who were also taking an acetylcholinesterase inhibitor (Nozomi, Ayu 2012). In a review of the evidence for curcumin and Alzheimer's disease, the researchers concluded that, to date, studies in people "have not been able to generate the anticipated benefits of curcumin," noting that this may be due, in part, to the low bioavailability and absorption of curcumin and the severity of disease progression in the people who participated (Goozee, Br J Nutr 2015).
Curcumin for osteoarthritis in dogs and cats:
A small study in dogs indicated that curcumin (4 mg/kg of body weight) taken twice daily could beneficially affect biochemical pathways associated with decreasing inflammation and pain and improving function in dogs with osteoarthritis; however, due to the size of the study, no conclusions could be drawn (Colitti, Vet Immunol Immunopathol 2012). The curcumin used in the study (Curcuvet, Indena) is a phytosomal formula containing 18-22% curcuminoids made by the makers of Meriva (which is also found in some joint supplements for pets, as well as for people). Curcumin as BCM-95 has been shown to reduce certain markers of chronic low-grade inflammation in obese cats (Leray, Br J Nutr 2011), but there are no studies of its effects in cats with osteoarthritis. Recommended dosing of curcumin for dogs ranges from 50 mg to 250 mg three times daily (depending on the size of the animal) or ½ teaspoon daily of whole turmeric twice daily, and, for cats, 50 mg to 100 mg daily or ¼ teaspoon daily of whole turmeric (Wynn, Veterinary Herbal Medicine 2007).
Be aware that polysorbate 80, which may be included in some curcumin formulations for people (such as Longvida), can cause severe allergic reactions in some dogs (Comblain, J Vet Pharmacol Ther 2016). However, no adverse effects were reported in dogs when black pepper extract, a bioavailability enhancer, was added to a food formulation containing curcumin and other ingredients (Head, J Alzheimers Dis 2012); there do not appear to be such safety studies cats. Unpleasant body odor in dogs taking curcumin has been reported (Dejonckheere, British Association of Veterinary Herbalists 2016). In addition, as with people, turmeric/curcumin should be avoided in dogs and cats taking certain medications or with certain medical conditions (see Concerns and Cautions).
Additional clinical studies of turmeric and curcumin in a variety of diseases are ongoing. More information about the clinical evidence for turmeric is available in the Encyclopedia article on this site.
Quality Concerns and What CL Tested for:
Like other supplements, neither the FDA nor any other federal or state agency routinely tests turmeric supplements for quality prior to sale. However, quality issues for turmeric supplements can include the following:
ConsumerLab.com, as part of its mission to independently evaluate products that affect health, wellness, and nutrition, purchased many turmeric or curcumin supplements sold in the U.S. and tested them to determine whether they 1) possessed the claimed and minimum expected amount of curcuminoid compounds, 2) were free of unacceptable levels of lead and cadmium, and 3) if regular tablets, could disintegrate properly in order to release their contents for absorption (see Testing Methods and Passing Score).
- Labeled Amount Does the product really contain the expected amount of turmeric or curcuminoid compounds?
- Purity Does the product contain contaminants? Like other supplements made from plant roots, turmeric may be contaminated with heavy metals, such as lead and cadmium. In children, infants, and fetuses, even low levels of lead can adversely affect neurobehavioral development and cognitive function. In adults, lead at somewhat higher levels can cause elevated blood pressure, anemia, and adversely affect the nervous and reproductive systems. Lead is of particular concern during pregnancy as the mother can transfer it to the fetus. Cadmium is a carcinogen and kidney toxin.
- Ability to Break Apart Properly Once in your body, will the pill break down properly (disintegrate) so that it can release its contents?
In light of a recent FDA report showing 7% of imported spices to be contaminated with the bacteria Salmonella and 12% with filth (e.g. insect parts), ConsumerLab.com also purchased several bottles of ground turmeric root spice, as used in cooking, and tested each for Salmonella and filth, as well as for lead and cadmium.
The manufacturer of a product which failed ConsumerLab.com's review due to inadequate label information has notified ConsumerLab.com that it has updated the labeling of the product. See the Update in the full review for details.