Plenty of studies have suggested that tea is a boon for cardiovascular health, but new research has found that adding milk to your favorite brew negates those benefits.
"There are a lot of studies that show that tea is protective against cardiac diseases," said lead researcher Dr. Verena Stangl, professor of cardiology at the Charite Hospital, Universitats-medizin-Berlin, in Germany. "If you look at the studies, you see that in Asia there are less cardiac diseases, but in England that's not the case. So the question is, is the addition of milk a reason for this difference between Asia and England, where tea is often taken with milk?" she said.
Sixteen healthy postmenopausal women drank either half a liter of freshly brewed black tea, black tea with skimmed milk or boiled water on three different occasions under similar conditions. The researchers then measured the function of the cells lining the brachial artery in the forearm, using high-resolution ultrasound before—and two hours after-tea consumption.
Stangl's team found that black tea significantly improved the ability of the arteries to relax and expand. "But when we added milk, we found the biological effect of tea was completely abolished," she said.
Additional experiments on rat aortas and rat endothelial cells—which line blood vessels—also found that tea relaxed the vessels. But adding milk blunted the effect.
The culprit in milk is a group of proteins called caseins, which interact with tea, decreasing its concentration of catechins. Catechins are flavonoids that are responsible for tea's protective effects against heart disease, according to the study authors.
"If you want to drink tea for its health effects, don't drink it with milk," Stangl said. Stang! noted that milk also destroys the antioxidant effects of tea and perhaps its cancer-protective effects as well.
Not Enough Sleep Increases Hypertension Risk
People who slept an average of five or fewer I hours per night were more than twice as likely to be diagnosed with hypertension over a 10-year follow-up period as people who averaged more than five hours a night. Blood pressure drops an average of 10% to 20% during sleep, so less sleep exposes the cardiovascular system to additional stress, which over time can raise blood pressure and lead to hypertension.
Best: Try to get seven to nine hours of sleep per night by allowing adequate time in bed...maintaining bedtimes...having a comfortable sleep environment.. avoiding alcohol and caffeine before sleep...and exercising regularly but not too close to bedtime.