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Tea time means only tea for optimal EGCG absorption

Many people drink green tea for health, and some take green tea or EGCG supplements in an attempt to shed extra fat. While these topics have been researched at length, there hasn’t been as much research on timing. This study looks at EGCG absorption with and without food.

Study under review: Food Inhibits the Oral Bioavailability of the Major Green Tea Antioxidant Epigallocatechin Gallate in Humans

Introduction

Epigallocatechin gallate (EGCG) or epigallocatechin-3-gallate (structure shown in Figure 1) is a catechin best known for being in various teas. Specifically, it’s one of the most abundant flavonoids present in the leaves from Camellia sinensis. The US Department of Agriculture reports that EGCG is found at concentrations of 42.45 mg/100 g of leaves in white tea and at 70.20 mg/100 g in green tea.

Figure 1: Flavans, catechins, and EGCG


EGCG, green tea and green tea extracts have been claimed to have antidiabetic[1], anticarcinogenic[2], weight loss[3] and anti-inflammatory properties[4]. However, when studied closer, the evidence becomes flimsy for some of these claims for a couple of reasons. One reason is that the biochemical components in green tea are different from those in extracts, which is again different from pure EGCG. In particular, green tea also contains three other catechins whose effects may be overlapping, as well as caffeine and theanine that each in their own right carries some biological activity. Thus, assigning biological activity to EGCG from studies using green tea or extracts is difficult. Furthermore, while EGCG and green tea extracts have shown promising results in several types of in vitro experiments, they have sometimes translated poorly[5] into human in vivo studies. As of now, the FDA does not condone health claims associated with EGCG or green tea.

Some of the discrepancies reported can possibly be attributed to varying bioavailability with different types of administration, especially as oral bioavailability appears to be quite poor in rodents, which does not appear to be the case for humans. Thus, while EGCG has been associated with many types of effects, the evidence is far from solid.

The purpose of the present study was to examine how well EGCG is absorbed in healthy humans when ingested alone, with a breakfast, or in a strawberry sorbet, and thus essentially to find out whether EGCG has better bioavailability when consumed with water and on empty stomach or when ingested with food.

Green tea and one of its active components, EGCG, have a lot of health claims associated with them, some more well-supported than others. However, one confounding factor in studying EGCG’s effects is its absorption from the gut and whether it depends on food consumption or not. The purpose of this study was to examine this question in healthy humans.

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