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The impact of the catechol-O-methyltransferase genotype on vascular function and blood pressure after acute green tea ingestion

Authors


Correspondence: Dr. Kim G. Jackson, Department of Food and Nutritional Sciences, University of Reading, P.O. Box 226, Whiteknights, Reading, Berkshire, RG6 6AP, UK

E-mail:k.g.jackson@reading.ac.uk

Fax: +44-118-378-7708

Abstract

Scope

Evidence for the benefits of green tea catechins on vascular function is inconsistent, with genotype potentially contributing to the heterogeneity in response. Here, the impact of the catechol-O-methyltransferase (COMT) genotype on vascular function and blood pressure (BP) after green tea extract ingestion are reported.

Methods and results

Fifty subjects (n = 25 of the proposed low-activity [AA] and of the high-activity [GG] COMT rs4680 genotype), completed a randomized, double-blind, crossover study. Peripheral arterial tonometry, digital volume pulse (DVP), and BP were assessed at baseline and 90 min after 1.06 g of green tea extract or placebo. A 5.5 h and subsequent 18.5 h urine collection was performed to assess green tea catechin excretion. A genotype × treatment interaction was observed for DVP reflection index (p = 0.014), with green tea extract in the AA COMT group attenuating the increase observed with placebo. A tendency for a greater increase in diastolic BP was evident at 90 min after the green tea extract compared to placebo (p = 0.07). A genotypic effect was observed for urinary methylated epigallocatechin during the first 5.5 h, with the GG COMT group demonstrating a greater concentration (p = 0.049).

Conclusion

Differences in small vessel tone according to COMT genotype were evident after acute green tea extract.

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