Bioavailability of Dietary Anthocyanins and Hydroxycinnamic Acids

Plant-derived polyphenolic compounds are ubiquitous in the diet, and evidence suggests that their chronic consumption may be associated with increased health benefits. Upon intake, these compounds are absorbed and extensively metabolized, resulting in their very low bioavailability. Anthocyanins and hydroxycinnamic acids are amongst the compounds being ingested daily in largest quantities, due to their presence in numerous food sources, including wine, grapes and berries (anthocyanins) and coffee, artichoke and blueberries (quinic ester of hydroxycinnamic acids, aka chlorogenic acids). Bioavailability studies have shown that anthocyanins are found in circulation at very low concentrations, in the sub-nanomolar range. Incubation of these compounds with fecal microbiota yields the production of phenolic acids from the degradation of the B-ring, subsequently increasing the overall bioavailability of anthocyanins. By contrast, hydroxycinnamic acids appear much more bioavailable when ingested as free compounds, but result in reduced absorption when conjugated to an ester moiety. A biphasic pharmacokinetic profile has been observed upon absorption and metabolism of chlorogenic acids, with hydroxycinnamic acids found rapidly in circulation after intake, followed by further metabolites deriving from a colonic metabolism and detected in circulation at a later time point, also found at greater concentrations.