Attention Tea Drinkers

English Breakfast tea and a 19th-century Limoges porcelain cup and saucer

Adding milk to tea cancels out the beverage's ability to protect against heart disease, according to German scientists. In a small study, researchers found drinking black tea significantly improved the ability of arteries to relax and expand to keep blood pressure healthy.
In an article published in the European Heart Journal, scientists said proteins in milk known as caseins block this effect. Molecules or catechins in the tea help dilate blood vessels by producing nitric oxide. The caseins in milk prevent this effect by reducing the concentration of catechins in tea.
Dr. Verena Stangl, senior researcher and professor of cardiology at Charite Hospital, Berlin, said the results provide "a possible explanation for the lack of beneficial effects of tea on the risk of heart disease in the UK, a country where milk is usually added."