Hi Sue! Beverages that contain caffeine are known to have an impact in the heart rate, mainly causing sinus tachycardia. Coffee and all drinks containing caffeine (including coca-cola) are stimulants of the heartbeat. Regarding your question, some types of tea contain low levels of caffeine (black tea, green tea, etc ). There are also some herbal tea that do not contain caffeine at all, such as camomille, ginger tea, peppermint tea etc. I would recommend the use of tea, especially herbal tea. In my opinion and experience, you can also use green or black tea, but since they have low amounts of caffeine you should not exagerate with the frequency of use during the day. In terms of cola, I would advise that you don t use it, since it contains considerable amount of caffeine. I hope my advices would be helpful to you. Take care and thanks for sharing your concern with us. Regards, Dr. P.Cerri