Detection of Plasma Curcuminoids from Dietary Intake of Turmeric-Containing Food in Human Volunteers

Scope: Curcumin (from turmeric), has been extensively investigated for potential beneficial properties in numerous diseases. Most work has focused on supra-dietary concentrations/doses that would necessitate curcumin supplementation. However, much evidence instigating curcumin research is underpinned by epidemiological data based on low dietary intake via turmeric consumption. Methods and results: Here, a novel, highly sensitive liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS) method for detection of curcuminoids is described. Assay sensitivity is demonstrated in a pilot pharmacokinetic volunteer study following ingestion of foodstuffs containing a standardized mass of turmeric, representative of daily consumption by certain South Asian populations. Free parent curcumin was detectable in plasma from one individual, reaching maximal plasma concentrations (C-max) of 3.2nm. Curcumin conjugates were detected in all volunteers; C-max for curcumin glucuronide is 47.6 +/- 28.5nm 30min post-food, while C-max for demethoxycurcumin glucuronide and curcumin sulfate is approximate to 2nm. Curcumin and its major metabolites persist in plasma for at least 8 h. Conclusion: Despite poor absorption and rapid conjugation, dietary intake of standard culinary turmeric within complex food matrices furnished human plasma with detectable levels of curcuminoids. Whether sustained low systemic concentrations of these non-nutritive, biologically active, dietary components may have pharmacological activity for human health benefit, warrants further research.