Introduction to the proceedings of the Fifth International Scientific Symposium on Tea and Human Health

The Fourth International Scientific Symposium on Tea and Human Health was held September 18, 2007 at the U.S. Department of Agriculture in Washington, DC. The symposium was organized by the Tea Council of the U.S.A. and cosponsored by the American Cancer Society, American College of Nutrition, American Medical Women’s Association, American Society for Nutrition, and the Linus Pauling Institute at Oregon State University. The symposium was cochaired by Lenore Arab (UCLA) and Jeffrey Blumberg (Tufts University). The proceedings of the first 3 symposia reflect the increasing rigor and productivity of research on the topic of tea and health (1–3). The organization of this symposium was prompted in part by the increase in publications on the topic since 2000, with over 330 in the last 3 y, and the value in considering not only the substantial and ongoing research efforts about the effect of tea on the risk for cardiovascular disease and cancer but the recently evolving investigations into other areas of health promotion and disease prevention. The history of tea as both a beverage and a medicine dates from 2737 BC, when Chinese legend describes Emperor Shen Nung’s discovery of tea not only as flavorful but producing vigor of body, contentment of mind, and determination of purpose. Indian lore mentions that Bodhidharma, the founder of Zen Buddhism, proposed tea as a gift to monks during meditation. Indeed, for centuries, tea was used principally as a medicinal drink before becoming a popular beverage during the Tang dynasty (AD 618–906). Modern investigations into the putative benefits of tea (Camellia sinsensis) began only 50 y ago with attention first directed largely by investigators in China, India, and Russia to its actions on blood pressure, carcinogenesis, central nervous system stimulation, gastrointestinal function, and iron bioavailability (4–7). The last 2 decades have seen tea research extending beyond cancer and cardiovascular disease to explore as well dental caries and plaque, bone mineral density and osteoporosis, and cognitive function and mood (8–10). Interestingly, if substantiated, the breadth of potential outcomes for tea consumption could contribute as 1 approach to health as defined by the World Health Organization as ‘‘a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity’’ (11). The goal of this symposium was to review the state of scientific advances relevant to the impact of tea consumption on physical health, mental performance, and disease prevention. Experimental models and human studies have consistently shown that cardiovascular disease risk factors reduce the production of endothelium-derived nitric oxide and impair endothelium-dependent vasodilation. The benefit of tea polyphenols in promoting nitric oxide bioavailability (12) is consistent with the meta-analysis of Peters et al. (13) showing that higher tea consumption is associated with a significant, but modest, 11% reduction in risk of heart disease. Kuriyama (14) updates this work with contributions from recent observational studies on tea and cardiovascular disease. He notes the challenge of conducting long-term randomized clinical trials on the effects of diet and lifestyle and suggests the need for continued refinement of prospective cohort studies to improve the precision of the exposure assessment. Grassi et al. (15) revisit the epidemiologic evidence and provide an in-depth examination of the mechanisms of action explored in human and animal experiments, particularly the effects of tea on nitric oxide-mediated pathways. They note the recent recommendation by the American College of Cardiology Foundation Task Force (16) for including moderate tea intake as part of nutritional advice for risk reduction of cardiovascular disease. There is a substantial body of evidence from animal models demonstrating an inhibition of cancer initiation and progres1 Published in a supplement to The Journal of Nutrition. Presented at the conference ‘‘Fourth International Scientific Symposium on Tea and Human Health,’’ held in Washington, DC at the U.S. Department of Agriculture on September 18, 2007. The conference was organized by the Tea Council of the U.S.A. and was cosponsored by the American Cancer Society, the American College of Nutrition, the American Medical Women’s Association, the American Society for Nutrition, and the Linus Pauling Institute. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Tea Council of the U.S.A. or the cosponsoring organizations. Supplement coordinators for the supplement publication were Lenore Arab, University of California, Los Angeles, CA and Jeffrey Blumberg, Tufts University, Boston, MA. Supplement coordinator disclosure: L. Arab and J. Blumberg received honorarium and travel support from the Tea Council of the U.S.A. for cochairing the Fourth International Scientific Symposium on Tea and Human Health and for editorial services provided for this supplement publication; they also serve as members of the Scientific Advisory Panel of the Tea Council of the U.S.A. 2 Supported by the Tea Council of the U.S.A.; U.S. Department of Agriculture Agricultural Research Service under Cooperative Agreement No. 58-1950-4-401. 3 Author disclosures: L. Arab and J. Blumberg received honoraria and travel support from the Tea Council of the U.S.A. for cochairing the Fourth International Scientific Symposium on Tea and Human Health and for editorial services provided for this supplement publication. L. Arab and J. Blumberg serve as members of the Scientific Advisory Panel of the Tea Council of the U.S.A. * To whom correspondence should be addressed: jeffrey.blumberg@tufts.edu.