Phyto-oestrogen content of berries, and plasma concentrationsand urinary excretion of enterolactone after asingle strawberry-meal in human subjects

Quantitative data on phyto-oestrogen, particularly lignan, content in edibl e plants are insufficient. We, therefore, measured isoflavonoids and lignan s in nine edible berries using an isotope dilution gas chromatography-mass spectrometry method for foods and found substantial concentrations of the l ignan secoisolariciresinol (1.39-37.18 mg/kg DM), low amounts of matairesin ol (0-0.78 mg/kg DM) and no isoflavones. To determine pharmacokinetics and urinary excretion pattern of the mammalian lignan enterolactone derived fro m plant lignans, a study with human subjects was conducted. Five healthy wo men and two men consumed, after a 72 h period of a phyto-oestrogen-free reg imen, a single strawberry-meal containing known amounts of plant lignans. B asal and post-meal blood and urine samples were collected at short interval s. The samples were analysed using time-resolved fluoroimmunoassay of enter olactone. The meal increased plasma concentration of enterolactone after 8- 24 h and in urine in the 13-24 h and 25-36 h urine collections. High indivi dual variability of the metabolic response was observed. Enterolactone excr eted in the urine collected throughout the 48 h post-meal yielded on averag e 114 % of the plant lignans consumed. It is concluded that berries contain ing relatively high concentrations of plant lignans contribute to plasma an d urinary levels of mammalian enterolactone in human subjects.