European Heart Journal Advance Access published online on May 5, 2007
European Heart Journal, doi:10.1093/eurheartj/ehm109
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Tea without milk: lifestyle advice based on a small lab study
German Cochrane Centre
Department of Medical Biometry and Medical Informatics
University Medical Centre
Freiburg
Germany
Department of Social and Preventive Medicine
University of Berne
Finkenhubelweg 11
CH-3012 Berne
Switzerland
Tel: +41 31 6313381
Fax: +41 31 6313520
E-mail address: vonelm{at}ispm.unibe.ch
German Cochrane Centre
Department of Medical Biometry and Medical Informatics
University Medical Centre
Freiburg
Germany
In their article, Lorenz et al. report results of experiments in 16 healthy post-menopausal women and of additional in vitro experiments in rat tissue.1 They infer that milk may counteract the known favourable effects of tea on vascular function. Further, they speculate that this finding may explain the lack of effect of tea on cardiovascular outcomes found in a previous population-based cohort study conducted in Caerphilly/Wales.2 In this study, almost all participants added milk to their tea, and consequently, there was no control group of ‘purist’ tea drinkers.
The European Society of Cardiology accompanied the publication of this study with a press release that amplified the authors' conclusions.3 As milk is in many tea-cups worldwide, it is not surprising that the ‘bad news for tea-drinking nations such as the British’ has spread rapidly and widely. Most related headlines left no room for doubt, e.g. ‘Milk cancels health benefit of drinking tea: study’4 or ‘Tea is good for you, but skip the milk’.5 Only few agencies took the time to produce a more balanced news piece by including additional information from an independent expert6 or additional literature.7 A simple explanation and some good advice sell better than the complexities of the real world. Also, it is well known that bad news is more likely to be published in newspapers than good news.8
Although the authors call for caution in the design of studies, they were less cautious when drawing inference from their data. The latter are derived from measurements in a few selected volunteers who drank tea in a laboratory and were not representative for any part of the population. Beyond the contentious question whether flavonoids in black tea are absorbed by milk proteins or not,9,10 evidence from relevant population-based studies is not yet in sight. Instead of measuring vasorelaxation, such studies would certainly choose outcomes that are more meaningful to populations, for instance, incidence of ischaemic heart disease.2 The present study could well serve as a starting point for the planning of such studies, but cannot replace them. It is hazardous to derive lifestyle advice from a single lab study. Such advice is likely to have a short shelf life when additional evidence is taken into account or new research data accumulate.
As doctors, we would not prescribe a new drug to patients if it was studied only in one small study. In analogy, milk abstinence should not be recommended to tea drinkers on the basis of evidence of similar strength. If science journalists carry news from the bench to excess, scientists should object. Publicity may help them along for a while, but they risk to be no longer heard by the public in the long term. Clearly, this story has not helped the case of public health. As long as the reported results are not confirmed in a fair number of humans who drink their tea outside the lab setting, we will continue to add milk to ours.
References
- Lorenz M, Jochmann N, von Krosigk A, Martus P, Baumann G, Stangl K, Stangl V. Addition of milk prevents vascular protective effects of tea. Eur Heart J (2007) doi:10.1093/eurheartj/ehl442.
- Hertog MG, Sweetnam PM, Fehily AM, Elwood PC, Kromhout D. Antioxidant flavonols and ischemic heart disease in a Welsh population of men: the Caerphilly Study. Am J Clin Nutr (1997) 65:1489–1494.
[Abstract/Free Full Text] - European Society of Cardiology. Press Releases 2007: Researchers warn milk eliminates cardiovascular health benefits of tea. http://www.escardio.org/vpo/Press+Area/Press+Releases/2007-esc-press-releases/milk-eliminates-cv-health-benefits-in-tea.htm (14 February 2007).
- Reuters. Milk cancels health benefit of drinking tea: study. http://today.reuters.com/news/articlenews.aspx?type=healthNews&storyID=2007-01-09T002337Z_01_L08837814_RTRUKOC_0_US-TEA.xml (14 February 2007).
- MSNBC. Tea is good for you, but skip the milk. http://www.msnbc.msn.com/id/16540633 (14 February 2007).
- BBC. Milk in tea ‘blocks health gains. http://news.bbc.co.uk/nolpda/ukfs_news/hi/newsid_6241000/6241139.stm (14 February 2007).
- Medscape. Milk blunts benefits of tea on endothelium. http://www.medscape.com/viewarticle/550549 (14 February 2007).
- Bartlett C, Sterne J, Egger M. What is newsworthy? Longitudinal study of the reporting of medical research in two British newspapers. BMJ (2002) 325:81–84.
[Abstract/Free Full Text] - Arts MJ, Haenen GR, Voss HP, Bast A. Masking of antioxidant capacity by the interaction of flavonoids with protein. Food Chem Toxicol (2001) 39:787–791.[CrossRef][Web of Science][Medline]
- Reddy VC, Vidya Sagar GV, Sreeramulu D, Venu L, Raghunath M. Addition of milk does not alter the antioxidant activity of black tea. Ann Nutr Metab (2005) 49:189–195.[CrossRef][Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||