British Journal of Nutrition

Full Papers

Human and Clinical Nutrition

Effect of moderate intakes of different tea catechins and caffeine on acute measures of energy metabolism under sedentary conditions

Nikolaj T. Gregersena1 c1, Christian Bitza1, Inger Krog-Mikkelsena1, Ole Helsa2, Eva M. R. Kovacsa3, Jane A. Rycrofta4, Erik Frandsena5, David J. Melaa6 and Arne Astrupa1

a1 Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark

a2 National Food Institute, Technical University of Denmark, Søborg, Denmark

a3 Unilever North America, Englewood Cliffs, NJ, USA

a4 Lipton Institute of Tea, Unilever R&D Colworth Park, Sharnbrook, Bedfordshire, UK

a5 Department of Clinical Physiology and Nuclear Medicine, Glostrup University Hospital, Glostrup, Denmark

a6 Unilever R&D Vlaardingen, Vlaardingen, The Netherlands

Abstract

Green tea may stimulate energy metabolism; however, it is unclear if acute effects are caused by specific catechins, caffeine or their combination. The objective of the present study was to examine the separate and combined effects of different catechins and caffeine on energy expenditure (EE) and fat oxidation over a single day. Fifteen healthy, normal-weight males received capsules containing placebo, caffeine alone (150 mg), or caffeine plus a catechin mixture (600 mg) enriched in either epigallocatechin-3-gallate (EGCG), epigallocatechin or a mix of catechins, in a randomised cross-over double-blinded design. On each test day EE, respiratory quotient (RQ) and substrate oxidation were measured under sedentary conditions in a respiratory chamber for 13·5 h. We found no significant treatment effect on EE (P = 0·20) or RQ (P = 0·68). EGCG with caffeine insignificantly raised EE and fat oxidation v. caffeine-only and placebo (EE 5·71 (se 0·12) v. 5·68 (se 0·14) v. 5·59 (se 0·13) MJ/12·5 h, respectively; fat oxidation 84·8 (se 5·2) v. 80·7 (se 4·7) v. 76·8 (se 4·0) g/12·5 h). Catechin/caffeine combinations at these dosages and mode of application had non-significant acute effects on EE and fat oxidation. The maximum observed effect on EE of about 2 % could still be meaningful for energy balance over much longer period of exposure. However, higher short-term effects reported in the literature may reflect variations in green tea extracts, added caffeine, or synergies with physical activity. The specific mechanisms and conditions that may underpin observed longer-term benefits of catechin-enriched green tea consumption on body composition remain to be confirmed.

(Received October 14 2008)

(Revised March 18 2009)

(Accepted April 07 2009)

(Online publication May 18 2009)

Correspondence:

c1 Corresponding author: Dr Nikolaj T. Gregersen, fax +45 35332483, email ntg@life.ku.dk

Footnotes

Abbreviations: ANCOVA, analysis of covariance; EE, energy expenditure; EGC, epigallocatechin; EGCG, epigallocatechin-3-gallate; HR, heart rate; RQ, respiratory quotient; SPA, spontaneous physical activity; VAS, visual analogue scale