From Washington, D.C., at the Fourth International Scientific Symposium on Tea and Human Health
Many people reach for a cup of coffee when they need to concentrate. People with flagging focus might, however, get more bang for the buck with a cup of tea. Theanine, an uncommon amino acid found almost exclusively in tea, works with caffeine to boost the activity of brain neurons, new data show.
John J. Foxe of the Nathan S. Kline Institute for Psychiatric Research in Orangeburg, N.Y., and his colleagues recruited 16 people for tests of attentiveness on four days. Before testing, each individual drank a glass of water. On 3 days, the drink was spiked with 100 milligrams of theanine, 60 mg of caffeine, or both. The theanine dose was equivalent to that in 4 to 5 cups of tea, and the caffeine translated to about 2.5 cups of tea.
In the difficult tests, participants watched a computer screen and pressed a button when a designated shape appeared on the side of a busy visual field to which an arrow had previously pointed. Participants’ accuracy differed little between days when they got water alone or with only one additive. Accuracy improved dramatically, however, on the day that they got the theanine-caffeine combination. The attention benefit lasted throughout the 3 hours of testing.
Brain activity, measured throughout each test, showed that theanine induced strong alpha waves in neurons, suggesting restfulness. But that lasted only until focus was required. Then, Foxe says, alpha activity dropped precipitously if a person had gotten theanine—especially in combination with caffeine—indicating that idling neurons had suddenly revved up their activity.
The study was funded by Unilever, which sells Lipton teas.