The Role of Catechol-O-Methyl Transferase Val(108/158)Met Polymorphism (rs4680) in the Effect of Green Tea on Resting Energy Expenditure and Fat Oxidation: A Pilot Study

IntroductionGreen tea(GT) is able to increase energy expenditure(EE) and fat oxidation(FATox) via inhibition of catechol-O-methyl transferase(COMT) by catechins. However, this does not always appear unanimously because of large inter-individual variability. This may be explained by different alleles of the functional COMT Val108/158Met polymorphism that are associated with COMT enzyme activity; high-activity enzyme, COMTH(Val/Val genotype), and low-activity COMTL(Met/Met genotype).MethodsFourteen Caucasian subjects (BMI: 22.2±2.3 kg/m2, age: 21.4±2.2 years) of whom 7 with the COMTH-genotype and 7 with the COMTL-genotype were included in a randomized, cross-over study in which EE and substrate oxidation were measured with a ventilated-hood system after decaffeinated GT and placebo(PL) consumption.ResultsAt baseline, EE, RQ, FATox and carbohydrate oxidation(CHOox) did not differ between groups. Significant interactions were observed between COMT genotypes and treatment for RQ, FATox and CHOox (pH genotype, but not for subjects carrying the COMTL genotype (EE, GT: 60.3 vs. PL: 51.7 kJ.3.5 hrs; NS), (RQ, GT: 0.81 vs. PL: 0.81; NS), (FATox, GT: 17.3 vs. PL: 17.0 g/d; NS), (CHOox, GT: 22.1 vs. PL: 21.4 g/d; NS).ConclusionSubjects carrying the COMTH genotype increased energy expenditure and fat-oxidation upon ingestion of green tea catechins vs, placebo, whereas COMTL genotype carriers reacted similarly to GT and PL ingestion. The differences in responses were due to the different responses on PL ingestion, but similar responses to GT ingestion, pointing to different mechanisms. The different alleles of the functional COMT Val108/158Met polymorphism appear to play a role in the inter-individual variability for EE and FATox after GT treatment.Trial RegistrationNederlands Trial register NTR1918