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The Golden Spice: What’s The Science Behind Turmeric?

Turmeric is a yellow-colored spice, which is commonly used in Indian cooking. It is derived from the root of the turmeric plant, a perennial herb scientifically known as Curcuma longa of the family Zingiberaceae, which also includes ginger –another favorite herb. Curcumin is the main active ingredient of turmeric, responsible for the spice’s distinctive yellow color.

Turmeric has been used in traditional medicine for centuries, claiming efficacy over a broad array of indications, such as osteoarthritis and rheumatoid arthritis, abdominal pain, dyspepsia, ulcerative colitis and Crohn’s, diarrhea, hepatitis, peptic ulcers and H. pylori infections. It has also been used for respiratory infections (bronchitis, flu, and common cold), hyperlipidemia, fatigue and fibromyalgia, and, last but not least, in certain types of cancer. Finally, due to its perceived anti-inflammatory activity, it has an excellent reputation against several autoimmune conditions such as lupus and multiple sclerosis. However, contrary to what usually happens with “panaceas,” most of these indications have convincing evidence to support their associated claims.

Notably, a literature search for curcumin or turmeric on PubMed returns several thousands of results, comprising preclinical and clinical trials, as well as reviews and meta-analyses. To gain an up-to-date insight on the latest research around this promising nutraceutical, we will examine select publications concerning various indications, beginning with, perhaps, the most well-studied one; inflammation.

Curcumin’s anti-inflammatory effects have been shown to occur through the downregulation of several cytokines, including the interleukins 1, 1β, 6, 8 and 12, TNF-α, MCP-1, and an array of inflammatory transcription factors and enzymes.1 Ample clinical evidence exists regarding curcumin’s efficacy on inflammatory diseases in humans. In a recent study, Abidi and colleagues showed that curcumin in capsule form was able to exert significant improvements in bronchial asthma when used as an add-on therapy to conventional treatment.2 As far as oral hygiene is concerned, curcumin has been found useful in the treatment of periodontal inflammatory conditions like chronic periodontitis and gingivitis. Although both of these conditions are treated with topical preparations, curcumin was found effective in multiple instances, and equal with the standard treatment of chlorhexidine-based topical gels and mouthwash solutions.3, 4

With regards to the inflammatory diseases of the gastrointestinal tract, several important studies have recently yielded promising results. Curcumin has been shown effective in ameliorating symptom severity in ulcerative colitis and Crohn’s disease, both through topical (e.g., in the form of an enema) and oral administration. Several researchers agree that curcumin can be regarded as a safe and effective add-on treatment for remission induction in inflammatory bowel diseases. 5,6

Curcumin’s most cited indication its anti-inflammatory activity in osteoarthritis (OA) and rheumatoid arthritis (RA). Several trials have shown that curcumin is highly effective in alleviating OA-related pain and increasing joint functionality.7 In fact, a very impressive recent finding has been that turmeric extract daily yielded improvements in OA-related metrics and pain comparable with ibuprofen, in patients with knee osteoarthritis! 8 As far as rheumatoid arthritis is concerned, curcumin has been tested in a pilot clinical trial in patients with active disease, where it improved all disease-related scores. 9

Another domain where curcumin has been shown highly effective is that of metabolic disease, namely obesity and diabetes. Regarding the former, curcumin does not induce weight loss, however, it has been shown to improve inflammatory biomarkers and reduce oxidative stress in obese patients, 10, 11 while also helping to reduce anxiety and depression symptoms that are commonly related to obesity. 12

There are several other conditions for which promising evidence exists, and the interested reader may refer to the scientific literature for data regarding neurological diseases such as Alzheimer’s, skin disease, or infectious diseases. However, no review of this potent, multi-purposed nutraceutical would be complete without referencing its potential to prevent or treat cancer.

Indeed, a growing body of evidence implies that curcumin may play a significant role in this regard. For instance, it was recently shown that curcumin was effective in clearing HPV from cervical tumors, without inducing any adverse effects. 13 Several studies have been undertaken in colon cancer patients, also yielding positive results in terms of inflammatory cytokines and other cancer-specific biomarkers. 14

Finally, before concluding this short review, special mention should be given to a couple of important details regarding curcumin’s safety and bioavailability. As far as the former is concerned, curcumin has been found remarkably safe and side-effect-free with orally administered doses of up to 12,000 mg per day. However, due to its poor absorption and extensive and fast metabolism, its bioavailability has been problematic. Still, there are several ways to circumvent this; one of the most widely used and inexpensive is its co-administration with piperine, the active substance of black pepper, which increases its bioavailability by up to 2,000%. Other solutions include curcumin’s encapsulation in liposomes and its coupling with molecules that enhance its stability and absorption.

 

REFERENCES

  1. Kunnumakkara A, Bordoloi D, Padmavathi G, Monisha J, Roy N, Prasad S et al. Curcumin, the golden nutraceutical: multitargeting for multiple chronic diseases. British Journal of Pharmacology. 2016;.
  2. Abidi A. Evaluation of Efficacy of Curcumin as an Add-on therapy in Patients of Bronchial Asthma. JOURNAL OF CLINICAL AND DIAGNOSTIC RESEARCH. 2014;.
  3. Gottumukkala S, Sudarshan S, Mantena Comparative evaluation of the efficacy of two controlled release devices: Chlorhexidine chips and indigenous curcumin based collagen as local drug delivery systems. Contemporary Clinical Dentistry. 2014;5(2):175.
  4. Pulikkotil S, Nath S. Effects of curcumin on crevicular levels of IL-1β and CCL28 in experimental gingivitis. Australian Dental Journal. 2015;60(3):317-327.
  5. Hanai H, Iida T, Takeuchi K, Watanabe F, Maruyama Y, Andoh A et al. Curcumin Maintenance Therapy for Ulcerative Colitis: Randomized, Multicenter, Double-Blind, Placebo-Controlled Trial. Clinical Gastroenterology and Hepatology. 2006;4(12):1502-1506.
  6. Lang A, Salomon N, Wu J, Kopylov U, Lahat A, Har-Noy O et al. Curcumin in Combination With Mesalamine Induces Remission in Patients With Mild-to-Moderate Ulcerative Colitis in a Randomized Controlled Trial. Clinical Gastroenterology and Hepatology. 2015;13(8):1444-1449.e1.
  7. Henrotin Y, Gharbi M, Dierckxsens Y, Priem F, Marty M, Seidel L et al. Decrease of a specific biomarker of collagen degradation in osteoarthritis, Coll2-1, by treatment with highly bioavailable curcumin during an exploratory clinical trial. BMC Complementary and Alternative Medicine. 2014;14(1).
  8. Kuptniratsaikul V, Dajpratham P, Taechaarpornkul W, Buntragulpoontawee M, Lukkanapichonchut P, Chootip C et al. Efficacy and safety of Curcuma domestica extracts compared with ibuprofen in patients with knee osteoarthritis: a multicenter study. CIA. 2014;:451.
  9. Chandran BGoel A. A Randomized, Pilot Study to Assess the Efficacy and Safety of Curcumin in Patients with Active Rheumatoid Arthritis. Phytotherapy Research. 2012;26(11):1719-1725.
  10. Ganjali S, Sahebkar A, Mahdipour E, Jamialahmadi K, Torabi S, Akhlaghi S et al. Investigation of the Effects of Curcumin on Serum Cytokines in Obese Individuals: A Randomized Controlled Trial. The Scientific World Journal. 2014;2014:1-6.
  11. Sahebkar A, Mohammadi A, Atabati A, Rahiman S, Tavallaie S, Iranshahi M et al. Curcuminoids Modulate Pro-Oxidant-Antioxidant Balance but not the Immune Response to Heat Shock Protein 27 and Oxidized LDL in Obese Individuals. Phytotherapy Research. 2013;27(12):1883-1888.
  12. Esmaily H, Sahebkar A, Iranshahi M, Ganjali S, Mohammadi A, Ferns G et al. An investigation of the effects of curcumin on anxiety and depression in obese individuals: A randomized controlled trial. Chinese Journal of Integrative Medicine. 2015;21(5):332-338.
  13. Basu P, Dutta S, Begum R, Mittal S, Dutta P, Bharti A et al. Clearance of Cervical Human Papillomavirus Infection by Topical Application of Curcumin and Curcumin Containing Polyherbal Cream: A Phase II Randomized Controlled Study. Asian Pacific Journal of Cancer Prevention. 2013;14(10):5753-5759.
Garcea G, Berry DP, Jones DJL, Singh R, Dennison AR, Farmer PB, et al. Consumption of the Putative Chemopreventive Agent Curcumin by Cancer Patients: Assessment of Curcumin Levels in the Colorectum and their Pharmacodynamic Consequences. Cancer Epidemiol Prev Biomarkers. 2005;14(1).