Food Inhibits the Oral Bioavailability of the Major Green Tea Antioxidant Epigallocatechin Gallate in Humans

Abstract

The bioavailability of the most abundant and most active green tea antioxidant, epigallocatechin gallate (EGCG) remains uncertain. Therefore, the systemic absorption of EGCG was tested in healthy fasted humans. It was administered as capsules with water or with a light breakfast, or when incorporated within a strawberry sorbet. The results for plasma EGCG clearly revealed that taking EGCG capsules without food was better; the AUC was 2.7 and 3.9 times higher than when EGCG capsules were taken with a light breakfast (p = 0.044) or with EGCG imbedded in the strawberry sorbet (p = 0.019), respectively. This pattern was also observed for Cmax and Cav. Therefore, ingesting food at the same time as EGCG, whether it was imbedded or not in food, substantially inhibited the absorption of the catechin. As with some types of medications that are affected by food, it appears that EGCG should be taken without food in order to maximise its systemic absorption. Therefore, based on these findings, ingesting EGCG with water on an empty stomach is the most appropriate method for the oral delivery of EGCG in clinical trials where EGCG is to be investigated as a potential bioactive nutraceutical in humans.

Keywords: EGCG; functional foods; green tea catechins; systemic absorption.

Figure 1

Typical HPLC-UV chromatograms (280 nm) of extracts from strawberry sorbet without (a) and with (b) the addition of EGCG (2.5 mg/g) and 4-aminosalycilic acid acting as internal standard (100 mmol/L).

Figure 2

Typical chromatogram of the internal standard, (+)-catechin (100 ng/mL) and EGCG (500 ng/mL) analyzed by HPLC and ESI-MS set in negative polarity SIM mode. When the EGCG peak in (a) was selected the molecular ion for EGCG (molecular mass-1) was clearly seen at 457 m/z (b).

Figure 3

Calibration curve for EGCG spiked into human plasma at increasing concentrations and detected using the optimised HPLC ESI-MS system.

Figure 4

Plasma EGCG concentration-time curves for each of the four individual participants for the three different methods of EGCG oral delivery: (a) capsules without breakfast; (b) capsules with breakfast; and (c) strawberry sorbet.

Figure 5

The mean plasma EGCG concentration-time curves for the three different methods of oral delivery: capsules without breakfast (green), capsules with breakfast (purple) and strawberry sorbet (red). The values are means ± the standard error of the means for the four participants (n = 4).