Tea naturally contains caffeine, which may cause a rapid heart rate, anxiety, insomnia, upset stomach and tremors
•Caffeine content in tea can range from 14 to 60 milligrams per cup, with black tea containing the highest levels, oolong tea containing moderate levels, and green and white teas containing relatively low levels.
• Consuming 200 to 300 milligrams of caffeine per day is considered moderate intake