|The lovely purple flowers of the Turmeric plant (Curcuma longa). Image: Depositphotos|
Turmeric, the bright yellow spice derived from the rhizome of curcuma longa plant, has been in research spotlight for over a decade. What is so precious about the Golden Spice and what exactly are scientists so excited about? Let's take a scientific look at turmeric with Brunswick Labs Ingredient Corner.
Turmeric (Curcuma longa) is a perennial plant from the ginger family (Zingiberaceae), native to South Asia and widespread throughout the Indian subcontinent and the tropical countries of Southeast Asia.1 Turmeric plants are highly branched and may reach up to 1 m in height. They have large, oblog leaves arranged in two rows and produce decorative, white, pink or purple flower spikes.
Almost the entire production of the world's turmeric crop takes place in India where 80% of this spice is also consumed.2 Turmeric powder is produced by peeling, boiling, drying and grinding the rhyzomes – horizontal underground stems that produce shoots above the ground and roots below the ground. The spice is traditionally used in savory, curry meat dishes, but may also be incorporated into rice-based desserts.
A long history of medicinal use
Turmeric has a long tradition of use in Indian Ayurvedic medicine (since about 1900 BC), in treatment of a wide range of common ailments, such as: jaundice, arthritis, nausea, flatulence, skin infections and wounds.1 In fact, turmeric has such a prominent position in Ayurweda that it is also known as the Ayurvedic Spice of Life. It is believed that by 700 and 800 AD, turmeric also found its way to China and East Africa.2 A legend has it that Marco Polo himself marveled at the properties of the Golden Spice, similar to those of the more familiar saffron:
“I have found a plant that has all the qualities of Saffron, but it is a root.”
(Marco Polo on turmeric, around 1280 AD)
Turmeric owes its bright yellow color to polyphenolic pigments also known as curcuminoids. With a chemical formula of C21H20O6, curcumin is the primary curcuminoid found in turmeric and its most active ingredient. Although it only accounts for approximately 3% of the weight of ground turmeric, this powerful ingredient has been associated with a range of beneficial biological functions ranging from antioxidant, anti-inflammatory and anticancer to antidiabetic and cardio-protective.1 It is believed that curcumin's effectiveness may, at least partially, be attributed to its immunomodulatory properties3 and the ability to affect multiple signalling pathways.4 Other, lesser-known phenolic constitutents of turmeric include demethoxycurcumin and bisdemethoxycurcumin. In addition, turmeric also contains volatile oils (tumerone, atlantone, and zingiberone), sugars, proteins and resins.
Getting around the bioavailability problem
Due to its favorable properties, turmeric has been incorporated in a wide variety of formulations, including: drinks, capsules, tablets, extracts and coloring agents. However, the enthusiasm about its biological effectiveness has been somewhat damped by studies pointing to curcumin’s poor absorption and bioavailability outside the gastrointestinal tract.5 Still, there are also reports that point to its chemotherapeutic and chemopreventive activity even at low concentrations ranging from 5-50 µM.6
Lately, some dietary supplement companies have focused their efforts on increasing the bioavailability of the golden ingredient in their formulations. Brunswick Labs recently tested two turmeric formulations (Lifekind tablets and Wholistic Turmeric capsules) provided by Pukka Herbs for their bioavailability, antioxidant effectiveness and anti-inflammatory potential.
The Caco-2 assay uses human colon carcinoma cells as the in vitro model of the human intestinal epithelium to test intestinal permeability and absorption. This assay is considered to be the method of choice for predicting in vivo intestinal absorption and bioavailability of an ingested substance. A number of curcuminoids and metabolites were followed in the assay, including curcumin, demethoxycurcumin and tetrahydrocurcumin. Thirty and 60 minutes after treatment with 0.5 mg/mL of the supplement, the results pointed to increased bioavailiability of tetrahydrocurcumin deriving from Lifekind tablets and Wholistic Turmeric capsules, compared to tetrahydrocurcumin deriving from two reference turmeric formulations.
Antioxidant effectiveness of turmeric
Turcumin’s antioxidant properties derive from its phenolic structure, which renders it capable of acting as a free radical scavenger and hydrogen donor.1 Turcumin also effectively binds metals, such as iron and copper, and exhibits both pro- and antioxidant activity.1
The cellular antioxidant assay, utilizing Nrf2 as the biomarker of antioxidant capacity, is often used to test antioxidant effectiveness of a compound. Nrf2 is a protein involved in the cellular response to oxidative damage caused by injury or inflammation. In this assay, increased Nrf2 production after trea-
|The turmeric rhizome. Looks like ginger or ginseng. Image: Depositphotos.|
tment with a test substance serves as the indicator of its antioxidant effectiveness. Test results indicated that the maximum Nrf2 production of Pukka Herb Lifekind tablets and Wholistic Turmeric capsules was 75.23% and 76.01%, respectively, which is comparable to the values determined for two reference turmeric formulations (78.36% and 71.32%).
Anti-inflammatory properties of turmeric
Research has shown that curcumin is a versatile molecule capable of modulating the inflammatory response by acting on numerous molecular targets involved in inflammation.7 One of the mechanisms by which curcumin exerts its anti-inflammatory effects is down-regulation of important enzymes involved in the inflammatory response - cyclooxygenase-2 (COX-2), lipoxygenase, and inducible nitric oxide synthase (iNOS), as well as inhibition of the production of inflammatory cytokines and tumor necrosis factor-alpha (TNF-a).
Due to its potent anti-inflammatory effects, curcumin has been shown to exhibit therapeutic potential in a number of chronic diseases associated with inflammation, such
as: Alzheimer’s and Parkinson’s diseases, multiple sclerosis, cardiovascular diseases, allergy, rheumatoid arthritis, diabetes, cancer, etc.8 In addition, preclinical studies on curcumin have shown that it inhibits carcinogenesis at various stages in a large number of cancer types, including but not limited to: colorectal, pancreatic, gastric, prostate, hepatic, breast, and oral cancer.9
A convenient assay for assessing the anti-inflammatory potential of a compound involves monitoring NF-κB inhibition. NF-κB is a protein complex involved in cellular responses to oxidative stress, ultraviolet irradiation, oxidized LDL and bacterial or viral infections. It plays an important role in regulating the immune response. In addition, NF-κB has been studied as a biomarker of inflammation, since suppression of NF-κB limits the production of proinflammatory genes. For illustration, the maximum NF-κB inhibition achieved by Pukka Herb Wholistic Turmeric capsules and Lifekind capsules was 66.23% and 69.18%, respectively.
Emerging research on turmeric
The in vitro assays outlined in the previous section can serve as an excellent foundation for additional preclinical and clinical studies of promising formulations. In the past ten years, we have seen a significant increase in the number of clinical studies focused on curcumin. A current search of the clinical trials database (www.clinicaltrials.gov) returns 25 actively recruiting studies focused on investigating the effects of curcumin on a range of diseases, including: rheumatoid arthritis, Parkinson’s disease, Alzheimer’s disease, colorectal cancer, Chron’s disease, breast cancer and schizophrenia.
Additional pre-clinical and clinical studies of the Golden Spice are likely in the near future, and Brunswick Labs looks forward to helping out on this important scientific quest. Next time you look at the rainbow of spices in your kitchen, reaching for the golden one will not only be a culinary preference, but also an informed choice backed by the centuries-old tradition of Indian healers.
- Bar Sela G, Epelbaum R, Schaffer M. Curcumin as an Anti-Cancer Agent: Review of the Gap Between Basic and Clinical Applications. Curcumin as an Anti-Cancer Agent: Review of the Gap Between Basic and Clinical Applications. Curr Med Chem. 2010; 17(3): 190-7.
- Sahdeo PandBharat BA. Ch. 13: Turmeric, the Golden Spice. In: Iris F.F. Benzie and Sissi Wachtel-Galor: Herbal Medicine: Biomolecular and Clinical Aspects. 2nd ed. Boca Raton FL: CRC Press; 2011:1-12.
- Castro CN, Barcala Tabarrozzi AE, Winnewisser J, et al. Curcumin ameliorates autoimmune diabetes. Evidence in accelerated murine models of type 1 diabetes. Clin Exp Immunol. 2014; 177(1): 149-60.
- Hatcher H, Planalp R, Cho J, et al. Curcumin: From ancient medicine to current clinical trials. Cell Mol Life Sci. 2008; 65: 1631-1652.
- Ireson CR, Jones DJ, Orr S. Metabolism of the cancer chemopreventive agent curcumin in human and rat intestine. Cancer Epidemiol Biomarkers Prev. 2002; 11:105-111.
- Garcea G, Jones DJ, Singh R, et al. Detection of curcumin and its metabolites in hepatic tissue and portal blood of patients following oral administration. Br J Cancer. 2004; 90: 1011-1015.
- Jurenka JS. Curcumin, a major constituent of Curcuma longa: A review of preclinical and clinical research. Alt Med Rev. 2009; 14(2): 141-153.
- Aggarwal BB, Harikumar B. Potential therapeutic effects of curcumin, the anti-inflammatory agent, against neurodegenerative, cardiovascular, pulmonary, metabolic, autoimmune and neoplastic diseases. Int J Biochem Cell Biol. 2009; 41(1): 40-59.
- Aggarwal BB, Kumar A, Bharti AC. Anticancer potential of curcumin: preclinical and clinical studies. Anticancer Res. 2003; 23:363-398.
Jasenka Piljac Zegarac is a scientist and freelance writer. She holds a PhD in biology and a BS degree in biochemistry, and contributes on a regular basis to several health and science blogs. Her research articles have gathered more than 900 citations. She may be contacted for assistance with a variety of science and medical writing projects.