**4. Influence of chirality on metabolism**

Another significant element of drug metabolism is chirality. Flavan-3-ols are chiral, and their potency and effect vary between enantiomers. According to research, (+)-catechin is more easily absorbed than (−)-catechin [25]. Similarly, comparative human studies about the bioavailability of (+)-catechin, (−)-catechin, (+)-epicatechin, and (−)-epicatechin reveals that (−) catechin is least bioavailable, followed by (+)-catechin, (+)-epicatechin, and (−)-epicatechin. These results were based on the analysis of urine and plasma samples from humans who consumed (−)-catechin, (+)-catechin, (+)-epicatechin, and (−)-epicatechin in equal quantity in a cocoa drink instead of green tea to avoid cross-contamination from flavan-3-ols present in green tea, which can alter the outcome of results [25, 26].
