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The impact of catechol-O-methyltransferase genotype on the acute responsiveness of vascular reactivity to a green tea extract

Miller, R. J., Jackson, K. G., Dadd, T., Mayes, A. E., Brown, A. L. and Minihane, A. M. (2011) The impact of catechol-O-methyltransferase genotype on the acute responsiveness of vascular reactivity to a green tea extract. British Journal of Nutrition, 105 (8). pp. 1138-1344. ISSN 1475-2662

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To link to this article DOI: 10.1017/S0007114510004836

Abstract/Summary

The beneficial effects of green tea catechins, such as the proposed improvement in endothelial function, may be influenced by phase II metabolism during and after absorption. The methylation enzyme, catechol-O-methyltransferase (COMT), has a missense mutation rs4680 (G to A), proposed to result in a 40 % reduction in enzyme activity. In the present pilot study, twenty subjects (ten of each homozygous COMT genotype) were recruited. Green tea extract capsules (836 mg green tea catechins) were given in a fasted state, and a high-carbohydrate breakfast was given after 60 min. Blood samples and vascular function measurements were taken at regular intervals. The change in digital volume pulse stiffness index (SI) from baseline was shown to be different between genotype groups at 120 and 240 min, with a lower SI in the GG individuals (P ≤ 0·044). The change in blood pressure from baseline also differed between genotype groups, with a greater increase in systolic (P = 0·023) and diastolic (P = 0·034) blood pressure at 120 min in the GG group. The AA group was shown to have a greater increase in insulin concentrations at 120 min (P = 0·019) and 180 min (P = 0·008) compared with baseline, despite similar glucose profiles. No genotypic differences were found in vascular reactivity measured using laser Doppler iontophoresis, total nitrite, lipids, plasma total antioxidant capacity or inflammatory markers after ingestion of the green tea extract. In conclusion, SI and insulin response to the glucose load differed between the COMT genotype groups, and this may be suggestive of a green tea extract and genotype interaction.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Human Nutrition Research Group
Interdisciplinary centres and themes > Institute for Cardiovascular and Metabolic Research (ICMR)
ID Code:24189
Uncontrolled Keywords:Blood pressure; Endothelial function; Flavan-3-ol; Green tea; Insulin
Publisher:Cambridge University Press

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