Original Article Modulating effect of COMT genotype on urinary metabolites of tea polyphenols in daily drinkers of green tea
Maki Inoue-Choi, Jian-Min Yuan, Chung S. Yang, David J. Van Den Berg, Mao-Jung Lee, Yu-Tang Gao, Mimi C. Yu
Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, 1300 S. Second St., WBOB Suite 300, Minneapolis, MN 55454, USA; The Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA; Department of Chemical Biology, Rutgers University, Piscataway, New Jersey, USA; USC/Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California, USA; Department of Epidemiology, Shanghai Cancer Institute, Shanghai, People’s Republic of China.
Received December 10, 2009; accepted December, 2009; available online January, 2010
Abstract: Available in vitro and animal studies have shown cancer protective effects of tea polyphenols. We recently reported an inverse association between green tea intake and breast cancer risk that was noted mainly among women possessing the low-activity genotype of the catechol-O-methyltransferase (COMT) gene, which may modulate the metabolism and excretion of tea polyphenols through urine. To determine the effect of COMT genotype on urinary excretion of tea polyphenol metabolites of daily green tea drinkers, we conducted a cross-sectional analysis within the Shanghai Cohort Study, a population-based, prospective investigation of cancer in 18,000 men, aged 45-64 years, who were enrolled during 1986-1989 in Shanghai, China. At baseline, in-person interview-based information together with blood and spot urine samples were obtained from each enrollee. In the present study, COMT genotype and five urinary metabolites of tea polyphenols were determined in 660 cohort subjects who self identified as daily drinkers of green tea. All urinary tea polyphenol measurements were expressed in units of urinary creatinine. Men possessing the homozygous low-activity COMT genotype (LL) exhibited statistically significantly lower urinary levels of individual as well as summation of the five tea polyphenol metabolites under study relative to individuals possessing the wild type high-activity COMT genotype (HH) or the heterozygous variant genotype (HL). Levels of urinary tea polyphenol metabolites were comparable between men possessing the HH and HL genotypes. Current findings are consistent with, and provide a biological rationale for the stronger protective effect of green tea intake among women possessing the low- versus high-activity COMT genotypes.(IJMEG912001).
Key words: Urinary tea polyphenols, green tea, COMT genotype
Address all correspondence to: Maki Inoue-Choi, PhD Division of Epidemiology and Community Health School of Public Health University of Minnesota 1300 S. Second St., WBOB Suite 300 Minneapolis, MN 55454 Tel: 612-625-4542, Fax: 612-624-0315 Email: email@example.com