Patient Education Healthy Living: The Hidden Benefits of Tea
Tea, coffee and water are amongst the most commonly consumed drinks globally, with tea being second only to water.1 But not all the health benefits of tea are commonly known. Here are nine fascinating reasons to put the kettle on…
1) HYDRATION: Many people believe that caffeinated drinks such as tea and coffee lead to dehydration. However, there is no scientific evidence to support this claim. In fact, tea has been recommended as second only to water, as a source of hydration, and a recent study showed that black tea contributes to the maintenance of normal hydration to a similar extent as water.20
2) ALERTNESS AND MOOD: Consuming low to moderate amounts of caffeine has been shown to have beneficial effects on mood and mental performance in most people.16 Consuming two to three cups of tea within 90 minutes has been proven to increase ones attention and alertness.
3) SLEEP: Sleep (amount and quality) is less likely to be disrupted when tea is consumed throughout the day instead of coffee.19 This is due to the lower levels of caffeine found in tea, where most people can consume tea later in the day without them experiencing a disrupted sleep.4) CARDIOVASCULAR HEALTH: Flavonoids are associated with good health outcomes, such as improved vascular function, which is linked to a lower risk of cardiovascular disease .24,25 As a rich source of flavonoids, the evidence for the positive role of tea in cardiovascular health continues to grow.26,27 Coffee has attracted interest as a potential contributor to coronary heart disease, but this has not been observed in population based studies.28,29 5) BLOOD PRESSURE: A recent review of relevant literature found that significant reductions in both systolic and diastolic blood pressure (–1.5mmHg,-1.3mmHg respectively) was associated with flavonoid intake.30 A study of regular tea drinkers with normal to mildly raised blood pressure, found that drinking three cups of black tea every day for six months lowered their blood pressure by 2-3mmHg (compared to a control group).31 With coffee, there is consistent evidence for an acute increase in blood pressure soon after drinking coffee (which does return to original levels within hours)32,33 However most coffee drinkers adapt to the tolerance of this hypertensive effect. The caffeine in coffee causes the effect on blood pressure. 6) TYPE 2 DIABETIES: A large long-term population study recently reported that drinking at least four cups of tea a day may reduce the risk of developing Type 2 diabetes by 16% (compared to non-tea drinkers).37 The protective effect is thought to be through the polyphenols naturally found in tea, improving insulin sensitivity and endothelial function.38,39 However in order to better understand the precise mechanism by which this protection occurs, more research needs to be conducted. Regular consumption of four or more cups of coffee a day may reduce the risk of developing Type 2 diabetes, although this association does not appear to hold true when drinking two or less cups a day.40,41 As there is some evidence for this protective association with decaffeinated coffee as well, the mechanism of action maybe via the non-caffeine components of coffee, possibly chlorogenic acid.4 7) WEIGHT LOSS: Regular long-term consumption of catechin- enriched green tea has been shown to reduce total body fat, specifically the fat round the waist, in Asian (Japanese and Chinese [green tea drinking cultures]) populations.42 Interestingly, a number of studies have found that combining exercise with catechin-enriched green tea beverages results in greater fat loss.43-45 There is limited evidence that drinking coffee (caffeinated or decaffeinated) is associated with weight loss.46-48 The reason for the weight loss could be due to the chlorogenic acid rather than the caffeine content of coffee. 8) DENTAL AND BONE HEALTH: Fluoride is essential for the prevention of dental caries and the promotion of healthy bone growth.50 On the other hand, there have been health issues raised about the amount of fluoride present in tea as well as fluoridated water. The amount of fluoride typically consumed through drinking water and brewed tea does not appear to pose a health risk.51 9) PHYSICAL PERFORMANCE: The general consensus is that caffeine (rather than tea or coffee per se) can improve performance in endurance sports, such as, running and cycling.52 Reviewing the evidence to date for tea, the key areas of potential good health benefits are mental wellbeing (alertness) and cardiovascular health, whereas for coffee, it is in the areas of immediate alertness and diabetes.
1. The Tea Association of the USA. Tea Fact Sheet – 2013. Accessed 06.11.2013, http://www.teausa.com/14655/tea-fact-sheet
20. Ruxton, CH, Hart, VA. Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomized controlled trial. British Journal of Nutrition, 2011; 106:588-595.
16. Ruxton, CHS. The impact of caffeine on mood, cognitive function, performance and hydration: a review of benefits and risks. Nutrition Bulletin, 2008; 33:15-25.
19. Hindmarch, I, Rigney, U, Stanley, N, Quinlan, P, Rycroft J, Lane, J. A naturalistic investigation of the effects of day-long consumption of tea, coffee and water on alertness, sleep onset and sleep quality. Psychopharmacology, 2000; 149:203–216.
24. Habauzit, V, Morand, C. Evidence for a protective effect of polyphenols-containing foods on cardiovascular health: an update for clinicians. Therapeutic Advances in Chronic Disease, 2012; 3(2):87-106.
25. Grassi, D, Desideri, G, Croce, G, Tiberti, S, Aggio, A, Ferri, C. Flavonoids, vascular function and cardiovascular protection. Current Pharmaceutical Design, 2009; 15(10):1072-1084.
26. Arab, L, Khan, F, Lam, H. Tea consumption and cardiovascular disease risk. American Journal of Clinical Nutrition, 2013; 98(6):1651S-9S.
27. Grassi, D, Desideri, G, Di Giosia, P, De Feo, M, Fellini, E, Cheli, P, Ferri, L, Ferri, C. Tea, flavonoids, and cardiovascular health: endothelial protection. American Journal of Clinical Nutrition, 2013; 98(6):1660S-6S.
28. Sofi, F, Conti, AA, Gori, AM, Eliana Luisi, ML, Casini, A, Abbate, R, Gensini, GF. Coffee consumption and risk of coronary heart disease: a meta-analysis. Nutrition, Metabolism and Cardiovascular Diseases, 2007; 17:209-223.
29. Wu, JN, Ho, SC, Zhou, C, Ling, WH, Chen, WQ, Wang, CL, Chen, YM. Coffee consumption and risk of coronary heart diseases: A meta-analysis of 21 prospective cohort studies. International Journal of Cardiology, 2009; 137(3):216-225.
30. Kay, CD, Hooper, L, Kroon, PA, Rimm, EB, Cassidy, A. Relative impact of flavonoid composition, dose and structure on vascular function: A systematic review of randomised controlled trials of flavonoid-rich food products. Molecular Nutrition and Food Research, 2012; 56:1605–1616.
31. Hodgson, JM, Puddey, IB, Woodman, RJ, Mulder, T, Fuchs, D, Scott, K, Croft, KD. Effects of black tea on blood pressure: a randomized controlled trial. Archives of Internal Medicine, 2012; 172(2):186-188.
32. Geleijnse, JM. Habitual coffee consumption and blood pressure: An epidemiological perspective. Vascular Health and Risk Management, 2008; 4(5):963-970.
33. Higdon, JV, Frei, B. Coffee and health: a review of recent human research. Critical Reviews in Food Science and Nutrition,2006; 46(2): 101-123.
37. The InterAct Consortium. Tea Consumption and Incidence of Type 2 Diabetes in Europe: The EPIC-InterAct Case-Cohort Study. PLoS One, 2012; 7(5):e36910.
38. Hyun, MK, Jaetaek, K. The Effects of Green Tea on Obesity and Type 2 Diabetes. Diabetes and Metabolism Journal, 2013; 37:173-175.
39. van Dam, RM, Naidoo, N, Landberg, R. Dietary flavonoids and the development of type 2 diabetes and cardiovascular diseases: review of recent findings. Current Opinion Lipidology, 2013; 24(1):25-33.
40. The Institute for Scientific Information on Coffee© . Coffee and health topics - Type 2 diabetes. Accessed 06.03.2013, www.coffeeandhealth.org/topics/type2diabetest
41. Muley, A, Muley, P, Shah, M. Coffee to reduce risk of type 2 diabetes?: a systematic review. Current Diabetes Reviews, 2012; 8(3): 162-8.
4. National Coffee Association USA n.d., The history of Coffee, Accessed 01.03.2013, http://www.ncausa.org/i4a/pages/index.cfm?pageid=68
42. Hursel, R et al. The effects of green tea on weight loss and weight maintenance: a meta-analysis. International Journal of Obesity, 2009; 33:956-961.
43. Kataoka, K, Takashima, S, Shibaka, E, Hoshino, E. Body fat reduction by the long term intake of catechins and the effects of physical activity. Progress in Medicine, 2004; 24:3358–3370.
44. Takashima, S, Kataoka, K, Shibaka, E, Hoshino, E. The long term intake of catechins improves lipid catabolism during exercise. Progress in Medicine, 2004; 24:3371–3379.
45. Maki, KC, Reeves, MS, Farmer, M, Yasunaga, K, Matsuo, N, Katsuragi, Y, Komikado, M, Tokimitsu, I, Wilder, D, Jones, F, Blumberg, JB, Cartwright, Y. Green tea catechin consumption enhances exercise induced abdominal fat loss in overweight and obese adults. Journal of Nutrition, 2009; 139(2):264-270.
46. Greenberg, JA, Axen, KV, Schnoll, R, Boozer, CN. Coffee, tea and diabetes: the role of weight loss and caffeine. International Journal of Obesity, 2005; 29(9):1121-1129.
47. Lopez-Garcia, E, van Dam, RM, Rajpathak, S, Willett, WC, Manson, JE, Hu FB. Changes in caffeine intake and long-term weight change in men and women. American Journal of Clinical Nutrition, 2006; 83(3):674-80.
48. Greenberg, JA, Boozer, CN, Geliebter, A. Coffee, diabetes and weight control. American Journal of Clinical Nutrition, 2006; 84:682-693.
50. EFSA (European Food Safety Authority): Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Fluoride, EFSA Journal (2005), 192, 1-65.
51. The United Kingdom Tea Council Ltd. Fluoride, Position Statement. 2006.
52. Spriet, LL, Graham, TE. Caffeine and Exercise Performance. American College of Sports Medicine, ACSM Current Comment Anabolic Steroids.