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Although many in vitro and animal studies have suggested a protective effect of green tea against breast cancer, findings from epidemiological studies have been inconsistent. No study has used prediagnostic biomarkers of tea polyphenols, which might play a protective role. A total of 24,226 women aged 40 to 69 years in the Japan Public Health Center-based Prospective Study who responded to the baseline questionnaire and provided blood in 1990-1995 were followed to December 2002. During a mean 10.6 years of follow-up, 144 newly diagnosed breast cancers were identified. Two matched controls for each case were selected from the cohort. Plasma levels of (-)-epigallocatechin (EGC), (-)-epicatechin (EC), (-)-epigallocatechin-3-gallate (EGCG), and (-)-epicatechin-3-gallate (ECG) were measured, and the odds ratio (OR) of breast cancer according to plasma level was estimated using a conditional logistic regression model. We found no statistically significant association between plasma tea polyphenol levels and breast cancer risk. Adjusted ORs for the highest versus lowest group were 0.90 (95% CI 0.42-1.96; P for trend = 0.98) for EGC, 0.95 (95% CI 0.43-2.08; P for trend = 0.86) for EC, 1.21 (95% CI 0.52-2.80; P for trend = 0.53) for EGCG, and 1.75 (95% CI 0.81-3.78; P for trend = 0.15) for ECG. Stratified analyses according to baseline menopausal status showed no remarkable difference between two strata. This nested case-control study found no overall association between plasma tea polyphenols and the risk of breast cancer in Japan.

Abundant in vitro and animal studies have shown a protective effect of green tea against various types of cancer, but the evidence from epidemiologic studies is inconclusive. In this nested case-control study, we used plasma biomarkers to directly investigate the effect of tea polyphenols on the risk of gastric cancer. Subjects were followed up from 1990 to 2004. Among 36,745 subjects who answered the baseline questionnaire and provided blood samples, 494 gastric cancer cases matched to 494 controls were used in the analysis. The validated method used high-performance liquid chromatography to analyze baseline plasma samples. For men, a high plasma level of (-)-epigallocatechin was associated with an increased risk of gastric cancer. For women, a high plasma level of (-)-epicatechin-3-gallate (ECG) was associated with a decreased risk of gastric cancer; the adjusted odds ratios (95% confidence intervals) for ECG levels 0.32 to 9.2 and 9.3+ ng/mL were 1.03 (0.41-2.59) and 0.25 (0.08-0.73), respectively, compared with those whose ECG level was under the detection limit (P for trend = 0.02). Cigarette smoking was suggested to play a role as an effect modifier, which explains in part the different patterns observed by gender.

Allergy-preventive activity was demonstrated for an extract of the bark of Populus sieboldii in a continuing search for allergy-preventive substances from natural sources. By bioassay-directed fractionation of this plant bark, two new phenolic glycosides, siebolside A {2-hydroxy-5-[(benzoyloxy)methyl]phenyl (6'-O-acetyl) beta-D-glucopyranoside} (1) and siebolside B {2-hydroxy-5-[(benzoyloxy)methyl]phenyl beta-D-glucopyranoside} (2), were isolated, together with three known compounds, salicin (3), sakuranin (4), and neosakuranin (5). The structures of 1 and 2 were elucidated by spectroscopic methods. Compounds 1-5 all showed allergy-preventive effects.

To assess human exposure to bisphenol A (BPA) over a 10-year period, BPA concentrations in maternal serum (MS) and amniotic fluid (AF) obtained at early second trimester were determined. ELISA was used to measure BPA in 200 MS/AF pairs in women carrying fetuses with normal karyotypes (Group I) and in 48 pairs with abnormal karyotypes (Group II). In Group I, BPA concentrations in AF (median: 0.26 ng/ml) were lower (P<0.01) than in MS (2.24 ng/ml). Over a 10-year period, yearly BPA concentrations in MS decreased from 5.62 to 0.99 ng/ml (P<0.001). Eight of the Group I AF samples had relatively high concentrations of BPA (2.80-5.62 ng/ml). In Group II, BPA concentrations in AF (0 ng/ml) were lower (P<0.01) than in MS (2.97 ng/ml). MS BPA concentrations in Group II were higher (P<0.01) than in Group I.