Milk counteracts the health benefits of tea

Written by Kevin Flatt

A surprising study by German scientists has revealed that adding milk to tea stops its ability to dilate blood vessels and give antioxidant benefits, two protective factors for a healthy heart and cardiovascular system, Catharine Paddock reported for Medical News Today on 9 Jan 2007.

The study is published online in the European Heart Journal and was conducted by a group of scientists from the University of Berlin's Charit Hospital.

Previous studies have shown that tea protects against cardiovascular disease, but nobody had investigated the effect of adding milk to the drink. Scientists have been puzzled about the fact that the UK, a high tea-consuming nation, does not report the extent of health benefits of other tea drinking populations. This could be because most tea in the UK is drunk with milk, the researchers say. (Medical News Today 9/1/2007).

Tests on volunteers showed that black tea significantly improves the ability of the arteries to relax and expand, but adding milk completely blunts the effect. Their study showed that the culprit in milk is a group of proteins called caseins, which they found interacted with the tea to decrease the concentration of catechins in the beverage. Catechins are the flavonoids in tea that mainly contribute to its protection against cardiovascular disease. (www.eurekalert.org).

The research, published in the European Heart Journal, involved studying 16 healthy post-menopausal women. They were given either 500ml of freshly brewed black tea, black tea with 10% skimmed milk or boiled water as a control. They drank it on three separate occasions but refrained from drinking tea for four weeks both before and after the study. The authors concluded that "milk counteracts the favourable health effects of tea on vascular function".

Senior researcher Dr Verena Stangl, professor of cardiology at the hospital, said the findings could also have implications for cancer. "Since milk appears to modify the biological activities of tea ingredients, it is likely that the anti-tumour effects of tea could be affected as well. I think it is essential that we re-examine the association between tea consumption and cancer protection, to see if that is the case." (Manchester Evening News. 9/1/2007).

(c) Copyright Kevin Flatt 2007

References

URL: http://www.medicalnewstoday.com/healthnews.php?newsid=60437

http://www.oxfordjournals.org/our_journals/eurheartj/press_releases/freepdf/ehl442.pdf

Manchester Evening News. Tuesday, 9th January 2007. Tea minus milk - for your heart's sake.
http://www.eurekalert.org/pub_releases/2007-01/esoc-rwm010907.php