Research has found that (11) _________________ drinking black tea can have a relaxing effect on the arteries (12) _____________ they expand and protect the heart, the tea has no effect at all if milk has been added. Tea without milk relaxes the arteries (13) _____________ produces nitric oxide (14) _____________ tea with milk has no effect at all. (15) _____________ tea is the second most popular drink in the world, after water, its health effects are of considerable importance. Researchers also suggest that other foods with known health benefits, such as olive oil and red wine, are looked at in context, (16) _____________ it can be determined whether they too lose their effects in combination with other foods.