Plasma Catechols After Eating Olives.

Olives contain 3,4-dihydroxyphenyl compounds (catechols)-especially 3,4-dihydroxyphenylethanol (DOPET)-that have therapeutic potential as nutraceuticals. Whether olive ingestion affects plasma levels of free (unconjugated) catechols has been unknown. Arm venous blood was sampled before and 15, 30, 45, 60, 120, 180, and 240 min after six healthy volunteers ate 10 Kalamata olives. Catechols were assayed by alumina extraction followed by liquid chromatography with series electrochemical detection. Plasma DOPET increased to 18.5 times baseline at 30 min (area under the curve (AUC) 39.2 ± 9.2 pmol-min/mL, P = 0.008). 3,4-Dihydroxyphenylacetic acid (DOPAC) increased markedly (peak 37.4 times baseline, AUC 23,490 ± 4,151 pmol-min/mL, P = 0.002). The sum of 10 catechols increased 12-fold (P < 0.0001). Eating olives produces large-magnitude increases in plasma levels of catechols, mainly DOPAC. DOPET seems to go undergo extensive hepatic metabolism to DOPAC.