"If you get migraines regularly then drinking green tea will make your migraines worse. I found this out the hard way. "
My colleague Mingruo Guo, Ph.D., a professor of food science at the University of Vermont and an authority on the immune-boosting potential of foods, always has a pot of green tea brewing. He drinks five to six cups a day, convinced that it has immune-enhancing effects along with other health benefits. Guo, who grew up drinking tea in China, credits tea’s polyphenols, potent plant antioxidants. One laboratory study suggested that a particular type of polyphenols called catechins may kill influenza viruses. Although just how they work isn’t fully known, research suggests that catechins, a particular type of polyphenols in green tea, may stimulate production and activity of some immune cells and inhibit the production of disease-promoting inflammatory compounds. One laboratory study found that catechins can kill influenza viruses.
Guo notes that many Americans are turned off by the bitterness of green tea—one downside of the polyphenols. But proper brewing techniques can help. To maximize benefits and minimize bitterness, the Tea Council recommends using just-below-boiling water and steeping green tea no more than a minute or two. A little lemon and honey can also help blunt the bitterness. But don’t add milk, because the proteins will bind to the polyphenols, making them ineffective.