Tea: Tea also sends your brain the message to perk up and pay attention. But tea has something coffee doesn't: the amino acid theanine. Theanine increases alpha brainwave activity, which helps you concentrate despite auditory and visual distractions, explains John Foxe, Ph.D., director of the Cognitive Neuroscience Program at City University of New York. Further, the antioxidants in tea may help prevent the oxidative stress thought to play a role in the development of Alzheimer's disease, says registered dietitian Marie Spano.
To Keep Your Bones Strong
Coffee: No matter what you may have heard, coffee doesn't stunt growth. Because of the high caffeine content in coffee, you'll lose a bit of calcium with each cup, but take in adequate calcium, and you'll still be standing tall. In a study of Swedish women, caffeine and coffee were associated with increased fracture only in women with the lowest calcium intakes. The real problem is having caffeinated drinks in lieu of bone-building, calcium-containing beverages.
Tea: Several studies suggest that tea drinkers have stronger bones. Adults older than 30 who were habitual tea drinkers for at least six years showed greater bone mineral density than non-tea drinkers. Researchers suspect tea's flavonoids, compounds with antioxidant and anti-inflammatory properties, improve bone mass. To gain the most advantage, choose brewed teas and steer clear of the bottled and instant teas.
To Love Your Heart
Coffee: Drink to your health! The more coffee you drink, the less likely you are to die from cardiovascular disease, says Martin. Among participants in the Nurse's Health Study and Health Professional Follow-up Study, coffee consumption reduced the risk for death from cardiovascular disease, independent of caffeine intake. So how much coffee should you drink? "If you can sleep, drink more," says Martin.
But beware: Unfiltered coffee like that prepared by boiling or French press contains compounds called diterpenes that raise LDL (bad) cholesterol. One more caveat: Some research has suggested that among high-risk individuals who rarely drink coffee and are slow metabolizers of caffeine, coffee may trigger a heart attack.
Tea: The more tea you drink, the lower your risk for heart disease, says Jeffrey Blumberg, Ph.D., director of the Jean Mayer USDA Human Nutrition Research Center on Aging. There is "some protection noted in those drinking one cup daily, more protection in those consuming two to three cups each day, and the lowest risk in those with intakes of four to five or more cups per day," he adds. Tea flavonoids inhibit the oxidation of
LDL-cholesterol, seem to reduce inflammation and improve the response of blood vessels to stress, he explains.
Jill Weisenberger is a registered dietitian and certified diabetes educator for the Hampton Roads Center for Clinical Research in Norfolk, Virginia.