Curcuminoids are the major bioactive molecules in turmeric (Curcuma longa, Zingiberaceae). They are amphiphilic compounds that are more soluble in organic solvents than aqueous solutions, and their low water solubility translates to poor gastrointestinal absorption. Moreover, the high rate of metabolism and metabolic inactivation and the rapid elimination of curcuminoids results in low serum curcuminoid levels and poor distribution of these compounds into tissues. Although they exhibit biological activity against various diseases, their poor bioavailability keeps curcuminoids from being used in many health and wellness applications. Developing a delivery system to enhance the absorption of curcumin, the principal curcuminoid of turmeric, in a suitable medium at an appropriate dose would enable the clinical applications of curcumin. This randomized, open-label, parallel study was conducted at Agile Pharma Services in Bangalore, India, to assess the bioavailability of a completely natural turmeric matrix formulation (CNTMF) and compare its bioavailability with that of two commercially available formulations in healthy adult males.
Marketed as Cureit and Acumin, the CNTMF was obtained from Aurea Biolabs (P) Ltd. in Cochin, India. It contained 46.5% total curcuminoids (36.0% curcumin, 9.0% demethoxycurcumin [DMC], and 1.5% bisdemethoxycurcumin [BDMC]), 43% total carbohydrates, 5% fiber, 2.4% proteins, and 3.2% volatile oil that consisted mainly of aromatic turmerone, dihydroturmerone, turmeronol, curdione, and bisacurone. One of the other commercially available formulations, marketed as Curcu-Gel Ultra (Tishcon Corp.; Westbury, New York), contained 85.9% curcuminoids (70.2% curcumin, 14.3% DMC, and 1.4% BDMC), with 7% to 9% essential oil that is naturally present in turmeric. The other formulation, available as Doctor’s Best Curcumin Phytosome (Doctor’s Best Inc.; Irvine, California), contained 19.8% curcuminoids (16.1% curcumin, 3.2% DMC, and 0.5% BDMC), with 40% phospholipids and 40% microcrystalline cellulose. The volatile oil and phospholipid formulations were purchased from Amazon online. The amounts of curcumin contained in 500 mg product capsules were 180 mg for CNTMF, 351 mg for the volatile oil formulation, and 80.5 mg for the phospholipid formulation.
Forty-five of the 51 males screened met the inclusion criteria, having a body mass index of 18.5 to 24.9 kg/m2 and no evidence of underlying disease as determined by pre-study screening, medical history, physical examination, and laboratory tests performed within 21 days of the beginning of the study. The subjects were randomly divided into three equal groups, with 15 subjects in each group participating. Vital signs were measured, and the subjects were questioned about their well-being before check-in, before dosing on the dosing day, and at 2, 4, 6, 12, and 24 hours after dosing. Any adverse effects were recorded. After eating a prepared dinner on the night before the dosing day, the subjects fasted overnight and for four hours after dosing. For one hour before and one hour after dosing, the subjects were not allowed to drink water.
On the dosing day, each subject was given a 500 mg capsule of the assigned formulation to take with 240 mL water. Lunch, snacks, and dinner were served at 4, 8, and 12 hours, respectively, afterward. All subjects completed the study, and no adverse effects were reported. A pre-dose blood sample was collected within one hour before dosing, and 18 samples were collected during the 24 hours following dosing.
The authors determined the pharmacokinetic parameters of curcuminoid concentrations by a mean area under the curve (AUC) ± standard deviation, maximum and minimum absorbance at each time point, and median for each formulation at the various time points. The results revealed a mean plasma maximum concentration (Cmax) of curcuminoids of 170.14 ng/mL in the CNTMF group compared with 47.54 ng/mL for the volatile oil formulation and 69.63 ng/mL for the phospholipid formulation. The bioavailability of the CNTMF was significantly greater than the other formulations (P<0.01). Maximum (Tmax) absorption was recorded at about 4 hours for the CNTMF (366 ng/mL), at 2.75 hours for the volatile oil formulation (104 ng/mL), and at 2.5 hours for the phospholipid formulation (138 ng/mL). These time points were not statistically different among the treatments.
Measurable blood levels of curcuminoids were not detected after 12 hours for the volatile oil (0.40 ± 0.60 ng/mL) and phospholipid (0.80 ± 1.10 ng/mL) formulations but were seen for the CNTMF (23.9 ± 22.2 ng/mL). The failure to detect curcuminoids 12 hours after consumption of the volatile oil and phospholipid formulations may have been due to much lower absorption from these products, rapid metabolism and removal from the blood, and, for the phospholipid formulation, a lower amount of curcuminoids, explain the authors. Comparing published pharmacokinetic data from studies of other formulations of curcuminoids, the authors found lower values for the Cmax and AUC per mg of curcuminoids in those studies, indicating that the CNTMF study product is more bioavailable than those formulations.
The authors conclude that the CNTMF facilitated the absorption and bioavailability of curcumin compared with the phospholipid and volatile oil formulations used in this study and with various other curcumin formulations evaluated in other studies. Limitations of the study are the inclusion of male subjects only and the lack of a crossover design. Eight of the authors are employees of Aurea Biolabs Ltd., a subsidiary of Plant Lipids Ltd., which provided the CNTMF for the study. Those authors are S. Gopi, J. Jacob, K. Varma, S. Jude, A. Amalraj, C.A. Arundhathy, R. George, and T.R. Sreeraj.
Gopi S, Jacob J, Varma K, et al. Comparative oral absorption of curcumin in a natural turmeric matrix with two other curcumin formulations: an open-label parallel-arm study. Phytother Res. December 2017;31(12):1883-1891. doi: 10.1002/ptr.5931.