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Polyphenols Unchanged, Heart Benefits Blunted

It’s called the “British Paradox”: Why doesn’t England’s tea consumption translate into the same protective effects observed in Asia? In the French Paradox, red wine polyphenols get credit for countering the effects of saturated fat in French cuisine. In the British Paradox, it’s milk that gets the blame for neutralizing tea’s polyphenol activity. But new findings suggest that blame might be misplaced: Scottish researchers found blood levels of polyphenols, thought by some researchers to be antioxidants, unchanged by the addition of milk to tea.

In the University of Aberdeen study, nine male volunteers ages 24-37 had their blood tested for polyphenol presence after drinking tea with and without milk. A brewing time of 7 minutes yielded the maximum polyphenol activity. Addition of milk did not compromise this effect. The results challenge previous assumptions that milk proteins bind with and neutralize tea polyphenols. But another recent study raises the possibility that milk may act in some other way to blunt tea’s possible cardiovascular benefits.

Tea consumption significantly lowers blood pressure — reducing hypertension risk by as much as 50% in one study. German researchers used ultrasound to observe how tea caused blood vessels to relax and expand, thus facilitating vascular flow. But when the healthy post-menopausal subjects drank tea with milk, the effect vanished. We contacted Mario Lorenz, co-author of the study published in the European Heart Journal, who conceded that “there are quite conflicting results around the impact of milk in tea…[which] contains a huge number of different substances.” Since milk doesn’t appear to mitigate polyphenol activity in tea, it’s possible some other milk-reactive compound may be buffering the blood pressure benefits. Moreover, heart health is just one of tea’s myriad advantages, including, other potential effects under study:

Lower cancer risk
Lower cholesterol
Dental health
Weight management

The jury is out on whether milk interferes with these benefits. In the meantime, those who prefer tea with milk may want to substitute soymilk or nondairy creamer, as suggested in “Heart Healthy Hot Chocolate.”

Published October 1, 2007

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