European Heart Journal Advance Access originally published online on May 5, 2007
European Heart Journal 2007 28(11):1397-1398; doi:10.1093/eurheartj/ehm107
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Milk casein and its benefits on cardiovascular risk: reply
Medizinische Klinik mit Schwerpunkt
Kardiologie und Angiologie
Charité—Universitätsmedizin Berlin
CCM
Charitéplatz 1
D-10117 Berlin
Germany
Medizinische Klinik mit Schwerpunkt
Kardiologie und Angiologie
Charité—Universitätsmedizin Berlin
CCM
Charitéplatz 1
D-10117 Berlin
Germany
Medizinische Klinik mit Schwerpunkt
Kardiologie und Angiologie
Charité—Universitätsmedizin Berlin
CCM
Charitéplatz 1
D-10117 Berlin
Germany
Tel: +49 30 450 513186, Fax: +49 30 450 513941, E-mail address: mario.lorenz{at}charite.de
We appreciate the interest of Prabhakar and Venkatesan in our study ‘Addition of milk prevents vascular protective effects of tea’.
The authors raise the question that the small sample size could lack statistical power and point out the failure to take the dietary habits of the participants into account. They further note that participants may have consumed other diary products, thus affecting also the control group.
We do not agree with the authors that the sample size in our study was too small. A total of 16 subjects (as in our study) is adequate for studies measuring endothelial function. In addition, our FMD results after consumption of the different beverages were highly significant. Addition of milk to tea not only reduced, but completely blunted the effects of tea on its own (P < 0.01; tea with milk compared with tea alone). Comparable studies measuring FMD in humans after consumption of beverages comprised a sample size similar to our study and also yielded statistical significant results: e.g. after consumption of red and white wine,1,2 black tea,3 and cocoa.4
As described under ‘Study design’ in our article, subjects with, for example, diabetes, obesity, and certain food patterns such as vegetarian lifestyle as well as high regular tea consumption were excluded from the study. All participants involved in the study fasted overnight, thus avoiding the confounding effects of other diary products. At the day of FMD measurement, all subjects received a standardized breakfast consisting of one croissant, thus limiting the influence of a surrounding food matrix on the FMD response. This information had all been outlined under ‘Study design’.
The authors comment on the beneficial effects of milk, including casein, on blood pressure and cardiovascular risk. The aim of our study was to investigate the interaction of milk with tea and to determine whether addition of milk (as practised in many countries) could have an adverse impact on the beneficial effects of tea alone on endothelial function. We do not question the beneficial effects of milk on its own. Also, our objective was not to investigate the effects of milk alone on the endothelium. However, recent publications have demonstrated the benefits of tea alone on mortality. A large prospective cohort study has shown that drinking green tea is associated with reduced cardiovascular disease and all-cause mortality.5
References
- Agewall S, Wright S, Doughty RN, Whalley GA, Duxbury M, Sharpe N. Does a glass of red wine improve endothelial function? Eur Heart J (2000) 21:74–78.
[Abstract/Free Full Text] - Whelan AP, Sutherland WH, McCormick MP, Yeoman DJ, de Jong SA, Williams MJ. Effects of white and red wine on endothelial function in subjects with coronary artery disease. Intern Med J (2004) 34:224–228.[CrossRef][Web of Science][Medline]
- Hodgson JM, Burke V, Puddey IB. Acute effects of tea on fasting and postprandial vascular function and blood pressure in humans. J Hypertens (2005) 23:47–54.[CrossRef][Web of Science][Medline]
- Schroeter H, Heiss C, Balzer J, Kleinbongard P, Keen CL, Hollenberg NK, Sies H, Kwik Uribe C, Schmitz HH, Kelm M. (–)-Epicatechin mediates beneficial effects of flavanol-rich cocoa on vascular function in humans. Proc Natl Acad Sci USA (2006) 103:1024–1029.
[Abstract/Free Full Text] - Kuriyama S, Shimazu T, Ohmori K, Kikuchi N, Nakaya N, Nishino Y, Tsubono Y, Tsuji I. Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study. JAMA (2006) 296:1255–1265.
[Abstract/Free Full Text]
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