Phytoestrogen Concentrations in Human Urine as Biomarkers for Dietary Phytoestrogen Intake in Mexican Women.

There has been substantial interest in phytoestrogens, because of their potential effect in reducing cancer and heart disease risk. Measuring concentrations of phytoestrogens in urine is an alternative method for conducting epidemiological studies. Our objective was to evaluate the urinary excretion of phytoestrogens as biomarkers for dietary phytoestrogen intake in Mexican women. Participants were 100 healthy women from 25 to 80 years of age. A food frequency questionnaire (FFQ) and a 24 h recall were used to estimate habitual and recent intakes of isoflavones, lignans, flavonols, coumestrol, resveratrol, naringenin, and luteolin. Urinary concentrations were measured by liquid chromatography (HPLC) coupled to mass spectrometry (MS) using the electrospray ionization interface (ESI) and diode array detector (DAD) (HPLC-DAD-ESI-MS). Spearman correlation coefficients were used to evaluate associations between dietary intake and urine concentrations. The habitual consumption (FFQ) of total phytoestrogens was 37.56 mg/day. In urine, the higher compounds were naringenin (60.1 µg/L) and enterolactone (41.7 µg/L). Recent intakes (24 h recall) of isoflavones (r = 0.460, p < 0.001), lignans (r = 0.550, p < 0.0001), flavonoids (r = 0.240, p < 0.05), and total phytoestrogens (r = 0.410, p < 0.001) were correlated to their urinary levels. Total phytoestrogen intakes estimated by the FFQ showed higher correlations to urinary levels (r = 0.730, p < 0.0001). Urinary phytoestrogens may be useful as biomarkers of phytoestrogen intake, and as a tool for evaluating the relationship of intake and disease risk in Mexican women.

Serum levels of phytoestrogens as biomarkers of intake in Mexican women.

Phytoestrogens have generated interest in human health in view of their potential effect to reduce the risk of developing chronic diseases. Serum levels of phytoestrogens have been proposed as an alternative to measure the exposure of phytoestrogens. We evaluated the use of serum as a biomarker of phytoestrogen's intake in healthy women. Phytoestrogens in serum (luteolin, kaempferol, equol, biochanin A, formononetin, quercetin, naringenin, coumestrol, secoisolariciresinol, genistein, matairesinol, enterolactone, enterodiol, daidzein, glycitein and resveratrol) were analyzed by HPLC-ESI-MS. Subjects were asked to recall all foods and beverages consumed the previous 24 h. Association of dietary intake and serum concentrations was performed by Spearman correlation. Correlations were found for naringenin (r = 0.47, p < 0.001), luteolin (r = 0.4 p < 0.001), genistein (r = 0.32, p < 0.01) enterolactone (r = 0.35, p = 0.0553), coumestrol (r = 0.26, p = 0.0835) and resveratrol (r = 0.29, p = 0.0517). Serum levels as biomarkers of intake along with a 24-h recall would be useful in order to investigate the relationship between phytoestrogens and health.