Tea, but no milk, please

The researchers, on three separate occasions, gave a group of 16 healthy women either half a liter of freshly brewed black tea or black tea with milk, or boiled water as a control. Using ultrasound, they measured artery expansion and relaxation in the forearm before and after.
They found that, while drinking tea helped to increase the blood flow compared with drinking water, adding milk wiped out the biological effect.
Tea drinkers who customarily add milk may want to consider omitting it sometimes, the researchers said.

I wonder if they knew what was expected?