New research reveals that drinking just one cup of regular, black tea per day may help to protect against cardiovascular disease. The research, conducted at the University of L'Aquila in Italy and supported by the Lipton Institute of Tea, is the first study to show that black tea consumption does - depending on dose - improve blood vessel reactivity, reduce both blood pressure and arterial stiffness, indicating a notably better cardiovascular health profile
Addition of milk prevents vascular protective effects of tea.
Lorenz M, Jochmann N, von Krosigk A, Martus P, Baumann G, Stangl K, Stangl V.
Eur Heart J. 2007 Jan;28(2):219-23. Epub 2007 Jan 9.
PMID: 17213230
doi:10.1093/eurheartj/ehl442
In conclusion, milk may counteract the favourable health effects of tea on vascular function. The finding that the tea-induced improvement of vascular function in humans is completely attenuated after addition of milk may have broad implications on the mode of tea preparation and consumption. In addition, it indicates that caution is warranted in the design of studies involving nutritional flavonoids.