Drink coffee see phantoms, drink tea, pr …

In Evidence-Based Medicine on January 22, 2009 by Danielle Tagged: , , , , , , , ,

Drink coffee, see phantoms; drink tea, prevent breast cancer. Hmm–that seems to be current medical wisdom according to newspapers.

I’ve spotted an article in the Telegraph that blares: “Drinking three cups of tea a day can cut the risk of breast cancer in women under 50 by more than a third”. This statement appears to be based on a non-randomised observational study that asked 4,501 ‘healthy’ women how much tea they had consumed over the 5 years before the study interview. 5,082 women with cancer were compared to this control group in terms of tea consumption. And the result of the study? “Tea consumption was not related to breast cancer risk overall” states the abstract, published in Cancer Epidemiology Biomarkers & Prevention. Then they did some fancy analysis (sorry: not too numerate and no full text) and looked at women under 50:

…Those consuming three or more cups per day had a 37% reduced breast cancer risk when compared with women reporting no tea consumption (age and study site–adjusted odds ratios, 0.63; 95% confidence intervals, 0.44-0.89; P = 0.01) with a significant test for trend (P = 0.01).

“Further research needed” is their conclusion–one that the Telegraph journalists ignore completely when reporting the study.  Do I smell some bad science here?  Does tea drinking prevent breast cancer, or do tea drinkers eat more fruits and veg, or exercise more, or do other health-preserving activities?  Remember: this study was done in the US, where coffee is king and those who drink tea also make their own yogurt and live in yurts.

Update: Cheers to NHS Choices and Bazian for selecting this study for analysis and comment in Behind the Headlines.  I suppose this means my ‘Howler Detector’ is working!  Read their take on it here.


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