For centuries, Curcuma longa (turmeric) was used as a spice in Asian cuisine and as a medicinal herb for treatment of inflammation, pain, wound healing, and digestive disorders, to name a few. Considerable preclinical research found that turmeric and its bioactive curcuminoid polyphenols can affect a variety of chronic conditions. Poor oral bioavailability of these curcuminoids hindered human trials investigating the efficacy of oral turmeric and its curcuminoids in treating various diseases and disorders. However, with the development of absorption-enhanced curcuminoid formulations in the past decade, dozens of clinical studies were conducted examining this spice's actions toward inflammatory conditions and glucose/lipid dysregulation. This narrative review of human trials addresses the scientific evidence for potential health benefits of turmeric and its curcuminoids in the treatment of arthritis, diabetes, and the metabolic syndrome and discusses recommendations for future research.
The spice turmeric is a botanical that is used widely in the Middle East and Asia, not only to impart a distinctive flavor to foods, but also purportedly to provide health benefits as a component of traditional medicines. Recently, it has been added to nutraceuticals, beverages, and processed foods. Turmeric is obtained from the rhizome of Curcuma longa L. (Zingiberaceae family) (Figure). Three curcuminoids, curcumin, demethoxycurcumin, and bisdemethoxycurcumin, of which curcumin is the most prevalent, are among many bioactive ingredients in turmeric. The yellow pigment curcumin or diferuloylmethane makes up 60% to 70% of crude turmeric extracts and is the principal curcuminoid evaluated for health-promoting activities. In addition, turmeric contains sugars, proteins, resins, and volatile oils, such as turmerone, atlantone, and zingiberene, some of which may have bioactivity as well. Numerous preclinical investigations identified a variety of potential health benefits, including treatment for heart disease, arthritis, Alzheimer's disease, gastrointestinal disorders, and the metabolic syndrome (MetS). Initial human trials examining the biological actions of oral curcumin given as raw turmeric powder (Figure) were confronted with its poor water solubility, low intestinal absorption, and rapid metabolic degradation, which limited its systemic distribution and bioavailability. Consumption of gram quantities of curcumin powder by human subjects was needed to obtain measurable amounts of circulating curcumin from which discernible biological actions were inconsistently observed. Over the previous decade, considerable research led to improvements in curcumin's bioavailability, which has contributed to the appearance of numerous clinical studies evaluating various possible health benefits of both turmeric and curcuminoids using these new delivery approaches. Such methods include inclusion of piperine, a phytochemical that enhances intestinal uptake of curcumin, and use of novel delivery systems that complex curcuminoids within diverse matrices. For example, curcumin can be incorporated into micelles, microemulsions, liposomes, nanoparticles, and in other lipid and biopolymer particles. Curcuminoids encapsulated with turmeric essential oils, particularly with turmerone, which enhances intestinal permeability, also have been prepared. Noticeable improvements in oral bioavailability in human subjects were reported using these novel formulations, and comparative efficacy have been reported for some the strategies. This narrative review examines human investigations into the effects of turmeric and its extracts and novel formulations on subjects with signs and symptoms of arthritis, type 2 diabetes mellitus (T2DM) and MetS. It may provide new insights into emerging potential health benefits of turmeric from the recent and growing number of human studies.
You must be logged in to post a comment.