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."
June Davison, a cardiac nurse at the British Heart Foundation (BHF) told the BBC it is difficult to say from this small study the impact adding a drop of milk to your tea can make. "The tea break is a great British tradition which provides time to relax with a cuppa in hand," she said. "Leaving milk out of your tea is far less likely to help protect your heart health than other measures, such as taking regular exercise, avoiding smoking and eating a healthy balanced diet." Davison said the study highlights the importance of thinking about interaction between different foods.