Dose-Dependent Increase in Unconjugated Cinnamic Acid Concentration in Plasma Following Consumption of Polyphenol Rich Curry in the Polyspice Study

Spices rich in polyphenols are metabolized to a convergent group of phenolic acids. We conducted a dose-exposure nutrikinetic study to investigate associations between mixed spices intake and plasma concentrations of selected, unconjugated phenolic acids. In a randomized crossover study, 20 Chinese males consumed a curry meal containing 0 g, 6 g, and 12 g of mixed spices. Postprandial blood was drawn up to 7 h at regular intervals and plasma phenolic acids were quantified via LC-MS/MS. Cinnamic acid (CNA, p < 0.0001) and phenylacetic acid (PAA, p < 0.0005) concentrations were significantly increased with mixed spices consumption, although none of the other measured phenolic acids differ significantly between treatments. CNA displayed a high dose-exposure association (R² > 0.8, p < 0.0001). The adjusted mean AUC_{0-7 h} for CNA during the 3 increasing doses were 8.4 ± 3.4, 376.1 ± 104.7 and 875.7 ± 291.9 nM·h respectively. Plasma CNA concentration may be used as a biomarker of spice intake.