Is it healthy to add milk to black tea?
The answer is complicated. Two studies have found that neither milk nor soy milk inhibit absorption of the antioxidants found in tea; one of these showed that milk actually increases the absorption of antioxidants. Other research has found that the antioxidant capacity of blood is lower in subjects who take tea with milk versus those who take it black. Yet another study showed that milk proteins block the relaxation effect tea can have on blood vessels. We need more studies using standardized preparations of tea, with and without additives, to answer the question with any certainty.
Interestingly, our institute completed a study published in the Journal of the American College of Nutrition that looked at key green tea molecules, including EGCG and the amino acid L-theanine, in encapsulated form to see if they could prevent cold and flu symptoms versus a placebo. Turns out the capsule reduced the incidence of cold and flu symptoms by more than 30 percent.
—Jack Bukowski, M.D., Ph.D., assistant clinical professor at Harvard Medical School and director of the Nutritional Science Research Institute