Tea and coffee, after water, are the most commonly consumed beverages in the world and are the top sources of caffeine and antioxidant polyphenols in the American diet. The purpose of this review is to assess the health effects of chronic tea and/or coffee consumption.
Tea consumption, especially green tea, is associated with significantly reduced risks for stroke, diabetes and depression, and improved levels of glucose, cholesterol, abdominal obesity and blood pressure. Habitual coffee consumption in large epidemiological studies is associated with reduced mortality, both for all-cause and cardiovascular deaths. In addition, coffee intake is associated with risks of heart failure, stroke, diabetes mellitus and some cancers in an inverse dose-dependent fashion. Surprisingly, coffee is associated with neutral to reduced risks for both atrial and ventricular arrhythmias. However, caffeine at high doses can increase anxiety, insomnia, calcium loss and possibly the risk of fractures.
Coffee and tea can generally be recommended as health-promoting additions to an adult diet. Adequate dietary calcium intake may be particularly important for tea and coffee drinkers.
aSaint Luke's Mid America Heart Institute & University of Missouri-Kansas City, Kansas City, Missouri
bJohn Ochsner Heart and Vascular Institute, Ochsner Clinical School, The University of Queensland School of Medicine, New Orleans
cDepartment of Preventive Medicine, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
Correspondence to James H. O’Keefe, MD, Saint Luke's Mid America Heart Institute, 4330 Wornall Rd, Ste 2000, Kansas City, MO 64111, USA. Tel: +1 816 751 8480; fax: +1 816 751 8665; e-mail: email@example.com