Are you recommending curcumin or turmeric to your patients?
Curcumin and turmeric are not interchangeable terms. Curcumin is a small, potent, and important part of turmeric. This distinction has implications for product selection as well as clinical dosing.
The discovery of the therapeutic potential of plant-derived remedies based on traditional medicine has raised interest in the development of drugs from natural sources.1 Over time, epidemiological studies have established an association between phytochemicals, including curcuminoids, and the range of biological activities that provide health benefits in humans.2
Traditional medicinal uses of turmeric include enhancing the immune system, reducing pain and swelling, and treatment for respiratory disorders such as asthma and allergies.4,5 Although the traditional uses of turmeric are still employed today, advances in modern medicine have revealed curcumin to be the key ingredient responsible for the pharmacological activities and therapeutic properties of turmeric.5
Studies have shown curcumin and turmeric to possess anti-inflammatory, anti- mutagenic, anti-microbial, antioxidant, cytotoxic, and immunomodulation properties.3-5
Turmeric (Curcuma longa) is a distinctive yellow spice, part of the ginger family (Zingiberacea) that has been used for thousands of years in Southeast Asia, China, and India for cooking and medicinal uses.3,4 Today, advances in modern nutrition have revealed curcumin to be the key ingredient responsible for the activities and therapeutic properties of turmeric.5
Active ingredients
Curcuminoids are a family of active compounds within turmeric. They are polyphenolic pigments and include curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Curcumin is the primary curcuminoid in turmeric and the compound on which most studies have been done. You can easily search for each of these curcuminoids as criteria in your favorite medical and scientific article database (e.g., PubMed) and compare the top results.
Although turmeric is thought to possess therapeutic properties, the curcuminoids found in the rhizome of turmeric contain only 2.5 to 6 percent curcumin. Curcumin compromises slightly more than 75 percent of the curcuminoid content.5 In other words, curcumin is the most abundant curcuminoid, and is also the most studied.
Curcuminoids are only a small fraction of the turmeric rhizome, and the rhizome is only one part of the plant. Unless explicitly stated that there is a different ratio of curcuminoids, it is assumed that the natural ratio of 77 percent curcumin, 17 percent demethoxycurcumin, and 3 percent bisdemethoxycurcumin with variances is maintained in a commercial product. This provides clarity to the conversation about using these plants in clinical practice.
Mode of action
To be an effective signaling molecule, curcumin must be delivered to the cell. To accomplish that effectively, concentrations must remain sufficiently high in the blood after first-pass metabolism.
Absorption takes place in the small intestine, and bioavailability is determined by the measurable amount of a substance found in blood circulation after biotransformation in the liver. Curcumin is bound to glucuronate as it circulates, and glucuronidase is an abundant enzyme at sites of inflammation and infection that acts on the bound, bio-transformed curcumin, allowing it to be released where it needs to be. This has implications for methodology in measuring the bioavailability of curcumin.
Simply comparing the number of milligrams on the label of curcumin, curcuminoids, or turmeric products fails to address the widely known challenge of bioavailability. Although curcumin has a wide range of biological activities, in vivo studies have found the bioavailability of curcumin in humans and animals to be low.4,5
Furthermore, curcumin has a high metabolizing rate and rapid systemic clearance.4,5 Because of its poor absorption efficiency, it is difficult for orally administered curcumin to reach blood levels sufficient to exert its bioactivity. To overcome this problem, several curcumin preparations have been developed that increase the bioavailability after oral administration with varying degrees of success.6
Forms that increase intestinal permeability assist the absorption of curcumin. Increased intestinal permeability is advantageous in treating a myriad of conditions such as allergies, asthma, autoimmunity, and more. One method allows the typically fat-soluble components to be water dispersible by using a preparation of colloidal submicron-particle curcumin. Another technology binds curcumin to other molecules to enhance absorption.
Clinical implications
Given these points, when recommending a curcumin product as a dietary supplement, you should opt for one that elevates measurable levels of curcumin in blood effectively and safely. The common pharmacokinetic assessment for bioavailability is “area under the curve” (AUC), measured in curcumin as nanograms per milliliter per hour (ng/mL/hr). This is an assessment over time (typically eight hours), rather than a single measurement or peak level after consumption.
These curves provide valuable insight as to how long an active compound remains elevated and quantifies how much of the compound is estimated to reach the target cells.
Bioavailability of novel preparations is often compared to curcumin extracts or other commercially available supplements.
Turmeric is an amazing plant and its rhizome is a true gift of nature. Curcuminoids—particularly curcumin— provide health benefits that are enhanced by proper and safe delivery systems. Patients rely on their healthcare practitioners to discern the most efficacious forms of dietary supplements. Therefore, it is important to evaluate new published literature in context of related evidence rather than rely exclusively on one or two highlighted experiments, expert opinion, or company-sponsored marketing materials.
Note that some patients have particular needs. For example, a patient following a vegan diet will require supplements that contain no animal products and athletes may request their supplements be NSF Certified for Sport.
Corey Schuler, DC, CNS, RN, LN, is the director of clinical affairs for Integrative Therapeutics. He practices in Hudson, Wisconsin. Schuler is also adjunct assistant professor at New York Chiropractic College, and is on the board of directors for the International Probiotics Association and an advisor to Functional Medicine University and active with the Board of Certification for Nutrition Specialists and the American College of Nutrition. He can be contacted through integrativepro.com.
References
1 Megalathan A, Kumarage S, Dilhari A, et al. Natural curcuminoids encapsulated in layered double hydroxides: a novel antimicrobial nanohybrid. Chem Cent J. 2016;10:35.
2 Policegoudra RS, Aradhya SM, Singh L. Mango ginger (curcuma amada roxb.)—a promising spice for phytochemicals and biological activities. J Biosci. 2011;36(4):739-48.
3 Sokmen M, Akram Khan M. The antioxidant activity of some curcuminoids and chalcones. Inflammopharmacology. 2016;24(2-3):81-6. 4 Asher GN, Spelman K. Clinical utility of curcumin extract. Altern Ther Health Med. 2013;19(2):20-2.
5 Lee W-H, Loo C-Y, Bebawy M, et al. Curcumin and its derivatives: their application in neuropharmacology and neuroscience in the 21st century. Current neuropharmacology. 2013;11(4):338-78.
6 Sunagawa Y, Hirano S, Katanasaka Y, et al. Colloidal submicron-particle curcumin exhibits high absorption efficiency-a double-blind, 3-way crossover study. J Nutr Sci Vitaminol (Tokyo). 2015;61(1):37-44.
